| author | Florian Pose <fp@igh-essen.com> |
| Fri, 26 Jun 2009 07:44:50 +0000 | |
| changeset 1483 | 43adf48aa157 |
| parent 1423 | 41e3baa2da23 |
| child 1485 | 5ddc3a455059 |
| permissions | -rw-r--r-- |
| 369 | 1 |
%------------------------------------------------------------------------------ |
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% IgH EtherCAT Master Documentation |
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% $Id$ |
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% vi: spell spelllang=en tw=78 |
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%------------------------------------------------------------------------------ |
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\documentclass[a4paper,12pt,BCOR6mm,bibtotoc,idxtotoc]{scrbook}
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\usepackage[latin1]{inputenc}
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\usepackage[automark,headsepline]{scrpage2}
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\usepackage{graphicx}
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\usepackage{makeidx}
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\usepackage[refpage]{nomencl}
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\usepackage{listings}
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\usepackage{svn}
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\usepackage{SIunits}
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\usepackage{hyperref}
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\hypersetup{pdfpagelabels,plainpages=false}
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\hypersetup{linkcolor=blue,colorlinks=true,urlcolor=blue}
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\setlength{\parskip}{0.8ex plus 0.8ex minus 0.5ex}
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{
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<5><6><7><8><9><10><10.95><12><14.4><17.28><20.74><24.88>cmttb10 |
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\lstset{basicstyle=\ttfamily\small,numberstyle=\tiny,aboveskip=4mm,
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belowskip=2mm,escapechar=`} |
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\renewcommand\lstlistlistingname{List of Listings}
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% Workaround for lstlistoflistings bug |
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\makeatletter% --> De-TeX-FAQ |
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\renewcommand*{\lstlistoflistings}{%
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\begingroup |
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\if@twocolumn |
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\@restonecoltrue\onecolumn |
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\else |
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\@restonecolfalse |
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\fi |
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\lol@heading |
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\setlength{\parskip}{\z@}%
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\setlength{\parindent}{\z@}%
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\setlength{\parfillskip}{\z@ \@plus 1fil}%
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\@starttoc{lol}%
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\if@restonecol\twocolumn\fi |
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\endgroup |
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} |
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\makeatother% --> \makeatletter |
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\renewcommand\nomname{Glossary}
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\newcommand{\IgH}{\raisebox{-0.7667ex}
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{\includegraphics[height=2.2ex]{images/ighsign}}}
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\SVN $Date$ |
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\SVN $Revision$ |
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\newcommand{\masterversion}{1.5.0}
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\newcommand{\linenum}[1]{\normalfont\textcircled{\tiny #1}}
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\makeindex |
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\makenomenclature |
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%------------------------------------------------------------------------------ |
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\begin{titlepage}
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\begin{center}
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\rule{\textwidth}{1.5mm}
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{\Huge\bf IgH \includegraphics[height=2.4ex]{images/ethercat}
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Master \masterversion\\[1ex] |
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Preliminary Documentation} |
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\vspace{1ex}
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\rule{\textwidth}{1.5mm}
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\vspace{\fill} {\Large Dipl.-Ing. (FH) Florian Pose,
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\url{fp@igh-essen.com}\\[1ex] Ingenieurgemeinschaft \IgH}
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\vspace{\fill}
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{\Large Essen, \SVNDate\\[1ex]
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Revision \SVNRevision} |
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\end{center}
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\end{titlepage}
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%------------------------------------------------------------------------------ |
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\tableofcontents |
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\listoftables |
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\listoffigures |
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%\lstlistoflistings |
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%------------------------------------------------------------------------------ |
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\newpage |
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\pagestyle{scrheadings}
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\section*{Conventions}
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\addcontentsline{toc}{section}{Conventions}
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\markleft{Conventions}
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The following typographic conventions are used: |
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\begin{itemize}
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\item \textit{Italic face} is used for newly introduced terms and file names.
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\item \texttt{Typewriter face} is used for code examples and command line
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output. |
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\item \texttt{\textbf{Bold typewriter face}} is used for user input in command
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lines. |
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\end{itemize}
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Data values and addresses are usually specified as hexadecimal values. These |
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are marked in the \textit{C} programming language style with the prefix
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\lstinline+0x+ (example: \lstinline+0x88A4+). Unless otherwise noted, address |
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values are specified as byte addresses. |
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Function names are always printed with parentheses, but without |
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parameters. So, if a function \lstinline+ecrt_request_master()+ has |
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empty parentheses, this shall not imply that it has no parameters. |
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If shell commands have to be entered, this is marked by a dollar prompt: |
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\begin{lstlisting}
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$ |
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\end{lstlisting}
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Further, if a shell command has to be entered as the superuser, the |
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prompt is a mesh: |
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\begin{lstlisting}
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# |
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\end{lstlisting}
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%------------------------------------------------------------------------------ |
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\chapter{The IgH EtherCAT Master}
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\label{chapter:master}
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\pagenumbering{arabic}
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This chapter covers some general information about the EtherCAT master. |
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%------------------------------------------------------------------------------ |
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\section{Feature Summary}
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\label{sec:summary}
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\index{Master!Features}
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The list below gives a short summary of the master features. |
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\begin{itemize}
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\item Designed as a kernel module for Linux 2.6. |
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\item Implemented according to IEC 61158-12 \cite{dlspec} \cite{alspec}.
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\item Comes with EtherCAT-capable drivers for several common Ethernet devices. |
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\begin{itemize}
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\item The Ethernet hardware is operated without interrupts. |
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\item Drivers for additional Ethernet hardware can easily be implemented |
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using the common device interface (see sec.~\ref{sec:ecdev}) provided by the
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master module. |
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\end{itemize}
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\item The master module supports multiple EtherCAT masters running in |
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parallel. |
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\item The master code supports any Linux realtime extension through its |
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independent architecture. |
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\begin{itemize}
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\item RTAI\nomenclature{RTAI}{Realtime Application Interface},
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ADEOS\nomenclature{ADEOS}{Adaptive Domain Environment for Operating
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Systems}, etc. |
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\item It runs well even without realtime extensions. |
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\end{itemize}
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\item Common ``Application Interface'' for applications, that want to use |
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EtherCAT functionality (see chap.~\ref{chap:api}).
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\item \textit{Domains} are introduced, to allow grouping of process
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data transfers with different slave groups and task periods. |
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\begin{itemize}
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\item Handling of multiple domains with different task periods. |
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\item Automatic calculation of process data mapping, FMMU and sync manager |
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configuration within each domain. |
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\end{itemize}
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\item Communication through several finite state machines. |
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\begin{itemize}
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\item Automatic bus scanning after topology changes. |
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\item Bus monitoring during operation. |
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\item Automatic reconfiguration of slaves (for example after power failure) |
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during operation. |
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\end{itemize}
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\item CANopen over EtherCAT (CoE) |
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| 369 | 232 |
\begin{itemize}
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\item SDO upload, download and information service. |
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\item Slave configuration via SDOs. |
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\item SDO access from userspace and from the application. |
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| 369 | 240 |
\end{itemize}
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\item Ethernet over EtherCAT (EoE) |
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| 369 | 244 |
\begin{itemize}
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\item Transparent use of EoE slaves via virtual network interfaces. |
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\item Natively supports either a switched or a routed EoE network |
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architecture. |
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| 369 | 251 |
\end{itemize}
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| 1364 | 253 |
\item Vendor-specific over EtherCAT (VoE) |
254 |
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255 |
\begin{itemize}
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256 |
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257 |
\item Communication with vendor-specific mailbox protocols via the API. |
|
258 |
||
259 |
\end{itemize}
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|
260 |
||
261 |
\item File Access over EtherCAT (FoE) |
|
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263 |
\begin{itemize}
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265 |
\item Loading and storing files via the command-line tool. |
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\item Updating a slave's firmware can be done easily. |
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\end{itemize}
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\item Userspace command-line-tool ``ethercat`` (see sec.~\ref{sec:tool})
|
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| 369 | 273 |
\begin{itemize}
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\item Detailed information about master, slaves, domains and bus |
276 |
configuration. |
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\item Setting the master's debug level. |
| 1364 | 278 |
\item Reading/Writing alias addresses. |
279 |
\item Listing slave configurations. |
|
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\item Viewing process data. |
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\item SDO download/upload; listing SDO dictionaries. |
|
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\item Loading and storing files via FoE. |
|
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\item Access to slave registers. |
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\item Slave SII (EEPROM) access. |
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\item Controlling application-layer states. |
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\item Generation of slave description XML from existing slaves. |
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| 369 | 288 |
\end{itemize}
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| 369 | 290 |
\item Seamless system integration though LSB\nomenclature{LSB}{Linux
|
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Standard Base} compliance. |
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| 369 | 293 |
\begin{itemize}
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\item Master and network device configuration via sysconfig files. |
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\item Init script for master control. |
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| 369 | 299 |
\end{itemize}
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| 369 | 301 |
\item Virtual read-only network interface for monitoring and debugging |
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purposes. |
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| 369 | 304 |
\end{itemize}
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||
306 |
%------------------------------------------------------------------------------ |
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\section{License}
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\label{sec:license}
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||
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The master code is released under the terms and conditions of the GNU General |
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Public License (GPL \cite{gpl})\index{GPL}, version 2. Other developers, that
|
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want to use EtherCAT with Linux systems, are invited to use the master code or |
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even participate on development. |
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To allow static linking of userspace application against the master's |
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application interface (see chap.~\ref{chap:api}), the userspace library (see
|
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sec.~\ref{sec:userlib}) is licensed under the terms and conditions of the GNU
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Lesser General Public License (LGPL \cite{lgpl})\index{LGPL}, version 2.1.
|
| 369 | 320 |
|
321 |
%------------------------------------------------------------------------------ |
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||
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\chapter{Architecture}
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| 1299 | 324 |
\label{chap:arch}
|
| 369 | 325 |
\index{Master!Architecture}
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||
327 |
The EtherCAT master is integrated into the Linux 2.6 kernel. This was |
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an early design decision, which has been made for several reasons: |
| 369 | 329 |
|
330 |
\begin{itemize}
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\item Kernel code has significantly better realtime characteristics, i.\,e.\ |
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less latency than userspace code. It was foreseeable, that a fieldbus master |
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has a lot of cyclic work to do. Cyclic work is usually triggered by timer |
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interrupts inside the kernel. The execution delay of a function that processes |
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timer interrupts is less, when it resides in kernelspace, because there is no |
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need of time-consuming context switches to a userspace process. |
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| 369 | 339 |
\item It was also foreseeable, that the master code has to directly |
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communicate with the Ethernet hardware. This has to be done in the kernel |
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anyway (through network device drivers), which is one more reason for the |
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master code being in kernelspace. |
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| 369 | 344 |
\end{itemize}
|
345 |
||
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Figure~\ref{fig:arch} gives a general overview of the master architecture.
|
| 369 | 347 |
|
348 |
\begin{figure}[htbp]
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|
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\centering |
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\includegraphics[width=.9\textwidth]{images/architecture}
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| 1291 | 351 |
\caption{Master Architecture}
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\label{fig:arch}
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| 369 | 353 |
\end{figure}
|
354 |
||
| 1291 | 355 |
The components of the master environment are described below: |
356 |
||
357 |
\begin{description}
|
|
358 |
||
359 |
\item[Master Module]\index{Master Module} Kernel module containing one or more
|
|
360 |
EtherCAT master instances (see sec.~\ref{sec:mastermod}), the ``Device
|
|
361 |
Interface'' (see sec.~\ref{sec:ecdev}) and the ``Application Interface'' (see
|
|
362 |
chap.~\ref{chap:api}).
|
|
363 |
||
364 |
\item[Device Modules]\index{Device modules} EtherCAT-capable Ethernet device
|
|
365 |
driver modules\index{Device modules}, that offer their devices to the EtherCAT
|
|
366 |
master via the device interface (see sec.~\ref{sec:ecdev}). These modified
|
|
367 |
network drivers can handle network devices used for EtherCAT operation and |
|
368 |
``normal'' Ethernet devices in parallel. A master can accept a certain device |
|
369 |
and then is able to send and receive EtherCAT frames. Ethernet devices |
|
370 |
declined by the master module are connected to the kernel's network stack as |
|
371 |
usual. |
|
372 |
||
373 |
\item[Application]\index{Application} A program that uses the EtherCAT master
|
|
374 |
(usually for cyclic exchange of process data with EtherCAT slaves). These |
|
375 |
programs are not part of the EtherCAT master code\footnote{Although there are
|
|
376 |
some examples provided in the \textit{examples/} directory.}, but have to be
|
|
377 |
generated or written by the user. An application can ``request'' a master |
|
378 |
through the application interface (see chap.~\ref{chap:api}). If this
|
|
379 |
succeeds, it has the control over the master: It can provide a bus |
|
380 |
configuration and exchange process data. Applications can be kernel modules |
|
381 |
(that use the kernel application interface directly) or userspace programs, |
|
382 |
that use the application interface via the EtherCAT library (see |
|
383 |
sec.~\ref{sec:userlib}).
|
|
384 |
||
385 |
\end{description}
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387 |
%------------------------------------------------------------------------------ |
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388 |
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\section{Master Module}
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\label{sec:mastermod}
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\index{Master module}
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The EtherCAT master kernel module \textit{ec\_master} can contain multiple
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master instances. Each master waits for a certain Ethernet device identified |
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by its MAC address\index{MAC address}. These addresses have to be specified on
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module loading via the \textit{main\_devices} module parameter. The number of
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master instances to initialize is taken from the number of MAC addresses |
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given. |
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The below command loads the master module with a single master instance that |
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waits for the Ethernet device with the MAC address |
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\lstinline+00:0E:0C:DA:A2:20+. The master will be accessible via index $0$. |
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\begin{lstlisting}
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# `\textbf{modprobe ec\_master main\_devices=00:0E:0C:DA:A2:20}`
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\end{lstlisting}
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MAC addresses for multiple masters have to be separated by commas: |
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\begin{lstlisting}
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# `\textbf{modprobe ec\_master main\_devices=00:0E:0C:DA:A2:20,00:e0:81:71:d5:1c}`
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\end{lstlisting}
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The two masters can be addressed by their indices 0 and 1 respectively (see |
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figure~\ref{fig:masters}). The master index is needed for the
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\lstinline+ecrt_master_request()+ function of the application interface (see |
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chap.~\ref{chap:api}) and the \lstinline+--master+ option of the
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\textit{ethercat} command-line tool (see sec.~\ref{sec:tool}), which defaults
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to $0$. |
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\begin{figure}[htbp]
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\centering |
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\includegraphics[width=.5\textwidth]{images/masters}
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\caption{Multiple masters in one module}
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\label{fig:masters}
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\end{figure}
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\paragraph{Debug Level} The master module also has a parameter
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\textit{debug\_level} to set the initial debug level for all masters (see
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also~\ref{sec:ethercat-debug}).
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\paragraph{Init Script}
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\index{Init script}
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In most cases it is not necessary to load the master module and the Ethernet |
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driver modules manually. There is an init script available, so the master can |
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be started as a service (see sec.~\ref{sec:system}).
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\paragraph{Syslog}
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440 |
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The master module outputs information about its state and events to the kernel |
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ring buffer. These also end up in the system logs. The above module loading |
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command should result in the messages below: |
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\begin{lstlisting}
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# `\textbf{dmesg | tail -2}`
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EtherCAT: Master driver `\masterversion` |
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EtherCAT: 2 masters waiting for devices. |
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449 |
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# `\textbf{tail -2 /var/log/messages}`
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Jul 4 10:22:45 ethercat kernel: EtherCAT: Master driver `\masterversion` |
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Jul 4 10:22:45 ethercat kernel: EtherCAT: 2 masters waiting |
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453 |
for devices. |
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\end{lstlisting}
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|
455 |
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All EtherCAT master output is prefixed with \lstinline+EtherCAT+ which makes |
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searching the logs easier. |
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%------------------------------------------------------------------------------ |
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460 |
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\section{Master Phases}
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\index{Master phases}
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Every EtherCAT master provided by the master module (see |
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sec.~\ref{sec:mastermod}) runs through several phases (see
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fig.~\ref{fig:phases}):
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\begin{figure}[htbp]
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\centering |
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\includegraphics[width=.9\textwidth]{images/phases}
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\caption{Master phases and transitions}
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\label{fig:phases}
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\end{figure}
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\begin{description}
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\item[Orphaned phase]\index{Orphaned phase} This mode takes effect, when the
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master still waits for its Ethernet device to connect. No bus communication is |
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possible until then. |
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\item[Idle phase]\index{Idle phase} takes effect when the master has accepted
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an Ethernet device, but is not requested by any application yet. The master |
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runs its state machine (see sec.~\ref{sec:fsm-master}), that automatically
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scans the bus for slaves and executes pending operations from the userspace |
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interface (for example SDO access). The command-line tool can be used to |
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access the bus, but there is no process data exchange because of the missing |
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bus configuration. |
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|
489 |
\item[Operation phase]\index{Operation phase} The master is requested by an
|
|
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|
490 |
application that can provide a bus configuration and exchange process data. |
|
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|
491 |
|
|
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|
492 |
\end{description}
|
|
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|
493 |
|
|
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|
494 |
%------------------------------------------------------------------------------ |
|
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|
495 |
|
|
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|
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\section{Process Data}
|
| 369 | 497 |
\label{sec:processdata}
|
498 |
||
|
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|
499 |
This section shall introduce a few terms and ideas how the master handles |
|
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|
500 |
process data. |
|
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|
501 |
|
| 369 | 502 |
\paragraph{Process Data Image}
|
503 |
\index{Process data}
|
|
504 |
||
|
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|
505 |
Slaves offer their inputs and outputs by presenting the master so-called |
|
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|
506 |
``Process Data Objects'' (PDOs\index{PDO}). The available PDOs can be either
|
|
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|
507 |
determined by reading out the slave's TXPDO and RXPDO SII categories from the |
|
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|
508 |
E$^2$PROM (in case of fixed PDOs) or by reading out the appropriate CoE |
|
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|
509 |
objects (see sec.~\ref{sec:coe}), if available. The application can register
|
|
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|
510 |
the PDOs' entries for exchange during cyclic operation. The sum of all |
|
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|
511 |
registered PDO entries defines the ``process data image'', which is exchanged |
|
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|
512 |
via datagrams with ``logical'' memory access (like LWR, LRD or LRW) introduced |
|
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|
513 |
in~\cite[sec.~5.4]{dlspec}.
|
| 369 | 514 |
|
515 |
\paragraph{Process Data Domains}
|
|
516 |
\index{Domain}
|
|
517 |
||
|
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|
518 |
The process data image can be easily managed by creating so-called |
|
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|
519 |
``domains'', which allow grouped PDO exchange. They also take care of managing |
|
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|
520 |
the datagram structures needed to exchange the PDOs. Domains are mandatory for |
|
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|
521 |
process data exchange, so there has to be at least one. They were introduced |
|
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|
522 |
for the following reasons: |
| 369 | 523 |
|
524 |
\begin{itemize}
|
|
|
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|
525 |
|
|
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|
526 |
\item The maximum size of a datagram is limited due to the limited size of an |
|
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|
527 |
Ethernet frame: The maximum data size is the Ethernet data field size minus |
|
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|
528 |
the EtherCAT frame header, EtherCAT datagram header and EtherCAT datagram |
|
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|
529 |
footer: $1500 - 2 - 12 - 2 = 1484$ octets. If the size of the process data |
|
a2a03519ee47
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|
530 |
image exceeds this limit, multiple frames have to be sent, and the image has |
|
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|
531 |
to be partitioned for the use of multiple datagrams. A domain manages this |
|
a2a03519ee47
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|
532 |
automatically. |
|
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changeset
|
533 |
|
|
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|
534 |
\item Not every PDO has to be exchanged with the same frequency: The values of |
|
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|
535 |
PDOs can vary slowly over time (for example temperature values), so exchanging |
|
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|
536 |
them with a high frequency would just waste bus bandwidth. For this reason, |
|
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merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
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|
537 |
multiple domains can be created, to group different PDOs and so allow separate |
|
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|
538 |
exchange. |
|
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|
539 |
|
| 369 | 540 |
\end{itemize}
|
541 |
||
|
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|
542 |
There is no upper limit for the number of domains, but each domain occupies |
|
a2a03519ee47
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|
543 |
one FMMU in each slave involved, so the maximum number of domains is de facto |
|
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|
544 |
limited by the slaves. |
| 369 | 545 |
|
546 |
\paragraph{FMMU Configuration}
|
|
547 |
\index{FMMU!Configuration}
|
|
548 |
||
|
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merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
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|
549 |
An application can register PDO entries for exchange. Every PDO entry and its |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
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changeset
|
550 |
parent PDO is part of a memory area in the slave's physical memory, that is |
|
1293
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Prcess data; slave configuration + attachment; typos.
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|
551 |
protected by a sync manager \cite[sec.~6.7]{dlspec} for synchronized access.
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
552 |
In order to make a sync manager react on a datagram accessing its memory, it |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
553 |
is necessary to access the last byte covered by the sync manager. Otherwise |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
554 |
the sync manager will not react on the datagram and no data will be exchanged. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
555 |
That is why the whole synchronized memory area has to be included into the |
|
1327
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merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
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changeset
|
556 |
process data image: For example, if a certain PDO entry of a slave is |
|
1293
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Prcess data; slave configuration + attachment; typos.
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changeset
|
557 |
registered for exchange with a certain domain, one FMMU will be configured to |
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
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changeset
|
558 |
map the complete sync-manager-protected memory, the PDO entry resides in. If a |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
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changeset
|
559 |
second PDO entry of the same slave is registered for process data exchange |
|
1293
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|
560 |
within the same domain, and it resides in the same sync-manager-protected |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
561 |
memory as the first one, the FMMU configuration is not altered, because the |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
562 |
desired memory is already part of the domain's process data image. If the |
|
1327
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merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
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changeset
|
563 |
second PDO entry would belong to another sync-manager-protected area, this |
|
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Prcess data; slave configuration + attachment; typos.
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changeset
|
564 |
complete area would also be included into the domains process data image. |
|
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Prcess data; slave configuration + attachment; typos.
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changeset
|
565 |
|
|
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|
566 |
Figure~\ref{fig:fmmus} gives an overview, how FMMUs are configured to map
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
567 |
physical memory to logical process data images. |
| 369 | 568 |
|
569 |
\begin{figure}[htbp]
|
|
570 |
\centering |
|
571 |
\includegraphics[width=\textwidth]{images/fmmus}
|
|
|
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|
572 |
\caption{FMMU Configuration}
|
| 369 | 573 |
\label{fig:fmmus}
|
574 |
\end{figure}
|
|
575 |
||
|
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Started to re-write the documentation.
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|
576 |
%------------------------------------------------------------------------------ |
|
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Started to re-write the documentation.
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changeset
|
577 |
|
|
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changeset
|
578 |
\chapter{Application Interface}
|
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
579 |
\label{chap:api}
|
|
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Started to re-write the documentation.
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|
580 |
\index{Application interface}
|
|
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|
581 |
|
| 1297 | 582 |
% TODO |
583 |
% |
|
584 |
% Interface version |
|
585 |
% Master Requesting and Releasing |
|
586 |
% Master Locking |
|
|
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|
587 |
% Configuring PDO assignment and mapping |
| 1297 | 588 |
% Domains (memory) |
|
1327
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|
589 |
% PDO entry registration |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
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changeset
|
590 |
% SDO configuration |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
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changeset
|
591 |
% SDO access |
|
1202
91d190223daa
Next changes for the documentation.
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diff
changeset
|
592 |
|
|
1094
eb0258e53236
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|
593 |
The application interface provides functions and data structures for |
| 1292 | 594 |
applications to access an EtherCAT master. The complete documentation of the |
595 |
interface is included as Doxygen~\cite{doxygen} comments in the header file
|
|
596 |
\textit{include/ecrt.h}. It can either be read directly from the file
|
|
|
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|
597 |
comments, or as a more comfortable HTML documentation. The HTML generation is |
| 1292 | 598 |
described in sec.~\ref{sec:gendoc}.
|
|
1094
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diff
changeset
|
599 |
|
|
eb0258e53236
App interface; doxygen; bib.
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diff
changeset
|
600 |
The following sections cover a general description of the application |
|
eb0258e53236
App interface; doxygen; bib.
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1087
diff
changeset
|
601 |
interface. |
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
602 |
|
|
eb0258e53236
App interface; doxygen; bib.
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parents:
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changeset
|
603 |
Every application should use the master in two steps: |
|
eb0258e53236
App interface; doxygen; bib.
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changeset
|
604 |
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
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diff
changeset
|
605 |
\begin{description}
|
|
eb0258e53236
App interface; doxygen; bib.
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changeset
|
606 |
|
|
eb0258e53236
App interface; doxygen; bib.
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changeset
|
607 |
\item[Configuration] The master is requested and the configuration is applied. |
|
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|
608 |
For example, domains are created, slaves are configured and PDO entries are |
|
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changeset
|
609 |
registered (see sec.~\ref{sec:masterconfig}).
|
|
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changeset
|
610 |
|
|
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|
611 |
\item[Operation] Cyclic code is run and process data are exchanged (see |
|
a2a03519ee47
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|
612 |
sec.~\ref{sec:cyclic}).
|
|
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changeset
|
613 |
|
|
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changeset
|
614 |
\end{description}
|
|
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changeset
|
615 |
|
|
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|
616 |
\paragraph{Example Applications}\index{Example Applications} There are a few
|
|
1204
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|
617 |
example applications in the \textit{examples/} subdirectory of the master
|
|
4e3e8400c338
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|
618 |
code. They are documented in the source code. |
|
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Removed examples; fixed undefines references; preliminary version.
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|
619 |
|
|
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|
620 |
%------------------------------------------------------------------------------ |
|
eb0258e53236
App interface; doxygen; bib.
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|
621 |
|
|
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App interface; doxygen; bib.
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|
622 |
\section{Master Configuration}
|
|
eb0258e53236
App interface; doxygen; bib.
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|
623 |
\label{sec:masterconfig}
|
|
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App interface; doxygen; bib.
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|
624 |
|
|
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|
625 |
The bus configuration is supplied via the application interface. |
|
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Prcess data; slave configuration + attachment; typos.
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|
626 |
Figure~\ref{fig:app-config} gives an overview of the objects, that can be
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
627 |
configured by the application. |
|
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|
628 |
|
|
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|
629 |
\begin{figure}[htbp]
|
|
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App interface; doxygen; bib.
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|
630 |
\centering |
|
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App interface; doxygen; bib.
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|
631 |
\includegraphics[width=.8\textwidth]{images/app-config}
|
|
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acb649738601
Some more documentation...
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|
632 |
\caption{Master Configuration}
|
|
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|
633 |
\label{fig:app-config}
|
|
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|
634 |
\end{figure}
|
|
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|
635 |
|
|
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Prcess data; slave configuration + attachment; typos.
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|
636 |
\subsection{Slave Configuration}
|
|
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Prcess data; slave configuration + attachment; typos.
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|
637 |
|
|
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Prcess data; slave configuration + attachment; typos.
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|
638 |
The application has to tell the master about the expected bus topology. This |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
639 |
can be done by creating ``slave configurations''. A slave configuration can be |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
640 |
seen as an expected slave. When a slave configuration is created, the |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
641 |
application provides the bus position (see below), vendor id and product code. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
642 |
|
|
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Prcess data; slave configuration + attachment; typos.
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|
643 |
When the bus configuration is applied, the master checks, if there is a slave |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
644 |
with the given vendor id and product code at the given position. If this is |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
645 |
the case, the slave configuration is ``attached'' to the real slave on the bus |
|
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Prcess data; slave configuration + attachment; typos.
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|
646 |
and the slave is configured according to the settings provided by the |
|
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Prcess data; slave configuration + attachment; typos.
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|
647 |
application. The state of a slave configuration can either be queried via the |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
648 |
application interface or via the command-line tool (see |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
649 |
sec.~\ref{sec:ethercat-config}).
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
650 |
|
|
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Prcess data; slave configuration + attachment; typos.
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|
651 |
\paragraph{Slave Position} The slave position has to be specified as a tuple
|
|
1306
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
Florian Pose <fp@igh-essen.com>
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changeset
|
652 |
of ``alias'' and ``position''. This allows addressing slaves either via an |
|
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Prcess data; slave configuration + attachment; typos.
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|
653 |
absolute bus position, or a stored identifier called ``alias'', or a mixture |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
654 |
of both. The alias is a 16-bit value stored in the slave's E$^2$PROM. It can |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
655 |
be modified via the command-line tool (see sec.~\ref{sec:ethercat-alias}).
|
|
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Prcess data; slave configuration + attachment; typos.
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|
656 |
Table~\ref{tab:slaveposition} shows, how the values are interpreted.
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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parents:
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diff
changeset
|
657 |
|
|
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Prcess data; slave configuration + attachment; typos.
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parents:
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changeset
|
658 |
\begin{table}[htbp]
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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parents:
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changeset
|
659 |
\centering |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
660 |
\caption{Specifying a Slave Position}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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|
661 |
\label{tab:slaveposition}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
662 |
\vspace{2mm}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
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changeset
|
663 |
\begin{tabular}{c|c|p{70mm}}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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changeset
|
664 |
Alias & Position & Interpretation\\ |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
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changeset
|
665 |
\hline |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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parents:
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diff
changeset
|
666 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
667 |
\lstinline+0+ & \lstinline+0+ -- \lstinline+65535+ & |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
668 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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parents:
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changeset
|
669 |
Position addressing. The position parameter is interpreted as the absolute |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
670 |
ring position in the bus.\\ \hline |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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parents:
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changeset
|
671 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
672 |
\lstinline+1+ -- \lstinline+65535+ & \lstinline+0+ -- \lstinline+65535+ & |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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changeset
|
673 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
674 |
Alias addressing. The position parameter is interpreted as relative |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
675 |
position after the first slave with the given alias address. \\ \hline |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
676 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
677 |
\end{tabular}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
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diff
changeset
|
678 |
\end{table}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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changeset
|
679 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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diff
changeset
|
680 |
Figure~\ref{fig:attach} shows an example of how slave configurations are
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
681 |
attached. Some of the configurations were attached, while others remain |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
682 |
detached. The below lists gives the reasons beginning with the top slave |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
683 |
configuration. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
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diff
changeset
|
684 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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diff
changeset
|
685 |
\begin{figure}[htbp]
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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parents:
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diff
changeset
|
686 |
\centering |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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diff
changeset
|
687 |
\includegraphics[width=.7\textwidth]{images/attach}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
688 |
\caption{Slave Configuration Attachment}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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changeset
|
689 |
\label{fig:attach}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
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diff
changeset
|
690 |
\end{figure}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
691 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
692 |
\begin{enumerate}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
693 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
694 |
\item A zero alias means to use simple position addressing. Slave 1 exists and |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
695 |
vendor id and product code match the expected values. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
696 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
697 |
\item Although the slave with position 0 is found, the product code does not |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
698 |
match, so the configuration is not attached. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
699 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
700 |
\item The alias is non-zero, so alias addressing is used. Slave 2 is the first |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
701 |
slave with alias \lstinline+0x2000+. Because the position value is zero, the |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
702 |
same slave is used. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
703 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
704 |
\item There is no slave with the given alias, so the configuration can not be |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
705 |
attached. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
706 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
707 |
\item Slave 2 is again the first slave with the alias \lstinline+0x2000+, but |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
708 |
position is now 1, so slave 3 is attached. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
709 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
710 |
\end{enumerate}
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
711 |
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
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diff
changeset
|
712 |
%------------------------------------------------------------------------------ |
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
713 |
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
714 |
\section{Cyclic Operation}
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
715 |
\label{sec:cyclic}
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
716 |
|
|
1293
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
717 |
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
718 |
To enter cyclic operation mode, the master has to be ``activated'' to |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
719 |
calculate the process data image and apply the bus configuration for the first |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
720 |
time. After activation, the application is in charge to send and receive |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
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1292
diff
changeset
|
721 |
frames. |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
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diff
changeset
|
722 |
|
| 1297 | 723 |
% TODO |
724 |
% |
|
725 |
% PDO endianess |
|
726 |
% Datagram injection |
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
727 |
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
728 |
%------------------------------------------------------------------------------ |
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
729 |
|
| 1298 | 730 |
\section{VoE Handlers}
|
731 |
\label{sec:api-voe}
|
|
732 |
||
733 |
During the configuration phase, the application can create handlers for the |
|
734 |
VoE mailbox protocol described in sec.~\ref{sec:voe}. One VoE handler always
|
|
735 |
belongs to a certain slave configuration, so the creation function is a method |
|
736 |
of the slave configuration. |
|
737 |
||
738 |
A VoE handler manages the VoE data and the datagram used to transmit and |
|
739 |
receive VoE messages. Is contains the state machine necessary to transfer VoE |
|
740 |
messages. |
|
741 |
||
742 |
The VoE state machine can only process one operation at a time. As a result, |
|
743 |
either a read or write operation may be issued at a time\footnote{If
|
|
744 |
simultaneous sending and receiving is desired, two VoE handlers can be created |
|
745 |
for the slave configuration.}. After the operation is initiated, the handler |
|
746 |
must be executed cyclically until it is finished. After that, the results of |
|
747 |
the operation can be retrieved. |
|
748 |
||
749 |
A VoE handler has an own datagram structure, that is marked for exchange after |
|
750 |
each execution step. So the application can decide, how many handlers to |
|
751 |
execute before sending the corresponding EtherCAT frame(s). |
|
752 |
||
753 |
For more information about the use of VoE handlers see the documentation of |
|
754 |
the application interface functions and the example applications provided in |
|
755 |
the \textit{examples/} directory.
|
|
756 |
||
757 |
%------------------------------------------------------------------------------ |
|
758 |
||
| 1294 | 759 |
\section{Concurrent Master Access}
|
|
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|
760 |
\label{sec:concurr}
|
|
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|
761 |
\index{Concurrency}
|
|
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|
762 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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|
763 |
In some cases, one master is used by several instances, for example when an |
|
1289
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Removed unnecessary modules; renamed references.
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|
764 |
application does cyclic process data exchange, and there are EoE-capable |
|
5b82b6b39c2d
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|
765 |
slaves that require to exchange Ethernet data with the kernel (see |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
766 |
sec.~\ref{sec:eoe}). For this reason, the master is a shared resource, and
|
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
767 |
access to it has to be sequentialized. This is usually done by locking with |
|
1085
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Started to re-write the documentation.
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|
768 |
semaphores, or other methods to protect critical sections. |
|
c75cdcc5ce87
Started to re-write the documentation.
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|
769 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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|
770 |
The master itself can not provide locking mechanisms, because it has no chance |
| 1291 | 771 |
to know the appropriate kind of lock. For example if the application is in |
772 |
kernelspace and uses RTAI functionality, ordinary kernel semaphores would not |
|
773 |
be sufficient. For that, an important design decision was made: The |
|
774 |
application that reserved a master must have the total control, therefore it |
|
775 |
has to take responsibility for providing the appropriate locking mechanisms. |
|
776 |
If another instance wants to access the master, it has to request the master |
|
777 |
lock by callbacks, that have to be set by the application. Moreover the |
|
778 |
application can deny access to the master if it considers it to be awkward at |
|
779 |
the moment. |
|
| 369 | 780 |
|
781 |
\begin{figure}[htbp]
|
|
782 |
\centering |
|
|
1085
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|
783 |
\includegraphics[width=.6\textwidth]{images/master-locks}
|
| 1295 | 784 |
\caption{Concurrent Master Access}
|
|
1085
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Started to re-write the documentation.
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|
785 |
\label{fig:locks}
|
| 369 | 786 |
\end{figure}
|
787 |
||
|
1204
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Removed examples; fixed undefines references; preliminary version.
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|
788 |
Figure~\ref{fig:locks} exemplary shows, how two processes share one master:
|
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
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|
789 |
The application's cyclic task uses the master for process data exchange, while |
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
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changeset
|
790 |
the master-internal EoE process uses it to communicate with EoE-capable |
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
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|
791 |
slaves. Both have to acquire the master lock before access: The application |
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
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|
792 |
task can access the lock natively, while the EoE process has to use the |
| 1294 | 793 |
callbacks. See the application interface documentation (chap.~\ref{chap:api})
|
794 |
for how to use the locking callbacks. |
|
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
795 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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|
796 |
%------------------------------------------------------------------------------ |
|
c75cdcc5ce87
Started to re-write the documentation.
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|
797 |
|
|
1202
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Next changes for the documentation.
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|
798 |
\chapter{Ethernet Devices}
|
|
1085
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Started to re-write the documentation.
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changeset
|
799 |
\label{sec:devices}
|
|
c75cdcc5ce87
Started to re-write the documentation.
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|
800 |
|
|
1203
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Some more documentation...
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|
801 |
The EtherCAT protocol is based on the Ethernet standard, so a master relies on |
|
acb649738601
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|
802 |
standard Ethernet hardware to communicate with the bus. |
|
1085
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Started to re-write the documentation.
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changeset
|
803 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
804 |
The term \textit{device} is used as a synonym for Ethernet network interface
|
|
c75cdcc5ce87
Started to re-write the documentation.
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|
805 |
hardware. There are device driver modules that handle Ethernet hardware, which |
|
1203
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|
806 |
a master can use to connect to an EtherCAT bus. |
| 369 | 807 |
|
808 |
%------------------------------------------------------------------------------ |
|
809 |
||
|
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|
810 |
\section{Network Driver Basics}
|
| 369 | 811 |
\label{sec:networkdrivers}
|
812 |
\index{Network drivers}
|
|
813 |
||
814 |
EtherCAT relies on Ethernet hardware and the master needs a physical |
|
815 |
Ethernet device to communicate with the bus. Therefore it is necessary |
|
816 |
to understand how Linux handles network devices and their drivers, |
|
817 |
respectively. |
|
818 |
||
819 |
\paragraph{Tasks of a Network Driver}
|
|
820 |
||
| 1095 | 821 |
Network device drivers usually handle the lower two layers of the OSI model, |
822 |
that is the physical layer and the data-link layer. A network device itself |
|
823 |
natively handles the physical layer issues: It represents the hardware to |
|
824 |
connect to the medium and to send and receive data in the way, the physical |
|
825 |
layer protocol describes. The network device driver is responsible for getting |
|
826 |
data from the kernel's networking stack and forwarding it to the hardware, |
|
827 |
that does the physical transmission. If data is received by the hardware |
|
828 |
respectively, the driver is notified (usually by means of an interrupt) and |
|
829 |
has to read the data from the hardware memory and forward it to the network |
|
830 |
stack. There are a few more tasks, a network device driver has to handle, |
|
831 |
including queue control, statistics and device dependent features. |
|
| 369 | 832 |
|
833 |
\paragraph{Driver Startup}
|
|
834 |
||
835 |
Usually, a driver searches for compatible devices on module loading. |
|
836 |
For PCI drivers, this is done by scanning the PCI bus and checking for |
|
837 |
known device IDs. If a device is found, data structures are allocated |
|
838 |
and the device is taken into operation. |
|
839 |
||
840 |
\paragraph{Interrupt Operation}
|
|
841 |
\index{Interrupt}
|
|
842 |
||
843 |
A network device usually provides a hardware interrupt that is used to |
|
|
1085
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Started to re-write the documentation.
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|
844 |
notify the driver of received frames and success of transmission, or |
| 369 | 845 |
errors, respectively. The driver has to register an interrupt service |
846 |
routine (ISR\index{ISR}\nomenclature{ISR}{Interrupt Service Routine}),
|
|
847 |
that is executed each time, the hardware signals such an event. If the |
|
848 |
interrupt was thrown by the own device (multiple devices can share one |
|
849 |
hardware interrupt), the reason for the interrupt has to be determined |
|
850 |
by reading the device's interrupt register. For example, if the flag |
|
851 |
for received frames is set, frame data has to be copied from hardware |
|
852 |
to kernel memory and passed to the network stack. |
|
853 |
||
|
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|
854 |
\paragraph{The \lstinline+net_device+ Structure}
|
| 369 | 855 |
\index{net\_device}
|
856 |
||
|
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|
857 |
The driver registers a \lstinline+net_device+ structure for each device to |
|
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|
858 |
communicate with the network stack and to create a ``network interface''. In |
|
1275
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|
859 |
case of an Ethernet driver, this interface appears as \textit{ethX}, where X
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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|
860 |
is a number assigned by the kernel on registration. The \lstinline+net_device+ |
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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|
861 |
structure receives events (either from userspace or from the network stack) |
|
1202
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|
862 |
via several callbacks, which have to be set before registration. Not every |
|
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|
863 |
callback is mandatory, but for reasonable operation the ones below are needed |
|
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|
864 |
in any case: |
|
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|
865 |
|
|
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|
866 |
\newsavebox\boxopen |
|
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|
867 |
\sbox\boxopen{\lstinline+open()+}
|
|
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Next changes for the documentation.
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|
868 |
\newsavebox\boxstop |
|
91d190223daa
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changeset
|
869 |
\sbox\boxstop{\lstinline+stop()+}
|
|
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changeset
|
870 |
\newsavebox\boxxmit |
|
91d190223daa
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|
871 |
\sbox\boxxmit{\lstinline+hard_start_xmit()+}
|
|
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Next changes for the documentation.
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|
872 |
\newsavebox\boxstats |
|
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|
873 |
\sbox\boxstats{\lstinline+get_stats()+}
|
| 369 | 874 |
|
875 |
\begin{description}
|
|
| 1095 | 876 |
|
|
1202
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|
877 |
\item[\usebox\boxopen] This function is called when network communication has |
|
1275
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|
878 |
to be started, for example after a command \lstinline+ip link set ethX up+ |
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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|
879 |
from userspace. Frame reception has to be enabled by the driver. |
|
1202
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|
880 |
|
| 1297 | 881 |
\item[\usebox\boxstop] The purpose of this callback is to ``close'' the |
|
1306
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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changeset
|
882 |
device, i.\,e.\ make the hardware stop receiving frames. |
|
1202
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|
883 |
|
|
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|
884 |
\item[\usebox\boxxmit] This function is called for each frame that has to be |
|
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|
885 |
transmitted. The network stack passes the frame as a pointer to an |
|
91d190223daa
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|
886 |
\lstinline+sk_buff+ structure (``socket buffer''\index{Socket buffer}, see
|
| 1095 | 887 |
below), which has to be freed after sending. |
888 |
||
|
1202
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|
889 |
\item[\usebox\boxstats] This call has to return a pointer to the device's |
|
91d190223daa
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changeset
|
890 |
\lstinline+net_device_stats+ structure, which permanently has to be filled with |
| 1095 | 891 |
frame statistics. This means, that every time a frame is received, sent, or an |
892 |
error happened, the appropriate counter in this structure has to be increased. |
|
893 |
||
894 |
\end{description}
|
|
895 |
||
896 |
The actual registration is done with the \lstinline+register_netdev()+ call, |
|
897 |
unregistering is done with \lstinline+unregister_netdev()+. |
|
| 369 | 898 |
|
|
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|
899 |
\paragraph{The \lstinline+netif+ Interface}
|
| 369 | 900 |
\index{netif}
|
901 |
||
|
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|
902 |
All other communication in the direction interface $\to$ network stack is done |
|
1202
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|
903 |
via the \lstinline+netif_*()+ calls. For example, on successful device opening, |
|
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|
904 |
the network stack has to be notified, that it can now pass frames to the |
|
91d190223daa
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|
905 |
interface. This is done by calling \lstinline+netif_start_queue()+. After this |
|
91d190223daa
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|
906 |
call, the \lstinline+hard_start_xmit()+ callback can be called by the network |
|
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|
907 |
stack. Furthermore a network driver usually manages a frame transmission queue. |
|
91d190223daa
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|
908 |
If this gets filled up, the network stack has to be told to stop passing |
|
91d190223daa
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|
909 |
further frames for a while. This happens with a call to |
|
91d190223daa
Next changes for the documentation.
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|
910 |
\lstinline+netif_stop_queue()+. If some frames have been sent, and there is |
| 1095 | 911 |
enough space again to queue new frames, this can be notified with |
912 |
\lstinline+netif_wake_queue()+. Another important call is |
|
913 |
\lstinline+netif_receive_skb()+\footnote{This function is part of the NAPI
|
|
914 |
(``New API''), that replaces the kernel 2.4 technique for interfacing to the |
|
915 |
network stack (with \lstinline+netif_rx()+). NAPI is a technique to improve |
|
916 |
network performance on Linux. Read more in |
|
917 |
\url{http://www.cyberus.ca/~hadi/usenix-paper.tgz}.}: It passes a frame to the
|
|
918 |
network stack, that was just received by the device. Frame data has to be |
|
|
1202
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|
919 |
included in a so-called ``socket buffer'' for that (see below). |
| 369 | 920 |
|
921 |
\paragraph{Socket Buffers}
|
|
922 |
\index{Socket buffer}
|
|
923 |
||
|
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|
924 |
Socket buffers are the basic data type for the whole network stack. They serve |
|
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Next changes for the documentation.
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|
925 |
as containers for network data and are able to quickly add data headers and |
|
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Next changes for the documentation.
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|
926 |
footers, or strip them off again. Therefore a socket buffer consists of an |
| 1095 | 927 |
allocated buffer and several pointers that mark beginning of the buffer |
|
1202
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|
928 |
(\lstinline+head+), beginning of data (\lstinline+data+), end of data |
|
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Next changes for the documentation.
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|
929 |
(\lstinline+tail+) and end of buffer (\lstinline+end+). In addition, a socket |
|
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|
930 |
buffer holds network header information and (in case of received data) a |
|
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changeset
|
931 |
pointer to the \lstinline+net_device+, it was received on. There exist |
|
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changeset
|
932 |
functions that create a socket buffer (\lstinline+dev_alloc_skb()+), add data |
|
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|
933 |
either from front (\lstinline+skb_push()+) or back (\lstinline+skb_put()+), |
|
91d190223daa
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|
934 |
remove data from front (\lstinline+skb_pull()+) or back |
|
91d190223daa
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|
935 |
(\lstinline+skb_trim()+), or delete the buffer (\lstinline+kfree_skb()+). A |
|
91d190223daa
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|
936 |
socket buffer is passed from layer to layer, and is freed by the layer that |
|
91d190223daa
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|
937 |
uses it the last time. In case of sending, freeing has to be done by the |
|
91d190223daa
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|
938 |
network driver. |
| 369 | 939 |
|
940 |
%------------------------------------------------------------------------------ |
|
941 |
||
|
1085
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Started to re-write the documentation.
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|
942 |
\section{EtherCAT Device Drivers}
|
|
1289
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|
943 |
\label{sec:drivers}
|
| 369 | 944 |
|
| 1095 | 945 |
There are a few requirements for Ethernet network devices to function as |
946 |
EtherCAT devices, when connected to an EtherCAT bus. |
|
| 369 | 947 |
|
948 |
\paragraph{Dedicated Interfaces}
|
|
949 |
||
| 1095 | 950 |
For performance and realtime purposes, the EtherCAT master needs direct and |
|
1202
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|
951 |
exclusive access to the Ethernet hardware. This implies that the network device |
|
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|
952 |
must not be connected to the kernel's network stack as usual, because the |
|
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|
953 |
kernel would try to use it as an ordinary Ethernet device. |
| 369 | 954 |
|
955 |
\paragraph{Interrupt-less Operation}
|
|
956 |
\index{Interrupt}
|
|
957 |
||
|
1202
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|
958 |
EtherCAT frames travel through the logical EtherCAT ring and are then sent back |
|
91d190223daa
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|
959 |
to the master. Communication is highly deterministic: A frame is sent and will |
|
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|
960 |
be received again after a constant time, so there is no need to notify the |
|
91d190223daa
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|
961 |
driver about frame reception: The master can instead query the hardware for |
|
91d190223daa
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|
962 |
received frames, if it expects them to be already received. |
| 1095 | 963 |
|
964 |
Figure~\ref{fig:interrupt} shows two workflows for cyclic frame transmission
|
|
965 |
and reception with and without interrupts. |
|
| 369 | 966 |
|
967 |
\begin{figure}[htbp]
|
|
968 |
\centering |
|
|
1202
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|
969 |
\includegraphics[width=.9\textwidth]{images/interrupt}
|
| 369 | 970 |
\caption{Interrupt Operation versus Interrupt-less Operation}
|
971 |
\label{fig:interrupt}
|
|
972 |
\end{figure}
|
|
973 |
||
| 1095 | 974 |
In the left workflow ``Interrupt Operation'', the data from the last cycle is |
975 |
first processed and a new frame is assembled with new datagrams, which is then |
|
976 |
sent. The cyclic work is done for now. Later, when the frame is received |
|
977 |
again by the hardware, an interrupt is triggered and the ISR is executed. The |
|
978 |
ISR will fetch the frame data from the hardware and initiate the frame |
|
979 |
dissection: The datagrams will be processed, so that the data is ready for |
|
980 |
processing in the next cycle. |
|
981 |
||
982 |
In the right workflow ``Interrupt-less Operation'', there is no hardware |
|
983 |
interrupt enabled. Instead, the hardware will be polled by the master by |
|
984 |
executing the ISR. If the frame has been received in the meantime, it will be |
|
985 |
dissected. The situation is now the same as at the beginning of the left |
|
986 |
workflow: The received data is processed and a new frame is assembled and |
|
987 |
sent. There is nothing to do for the rest of the cycle. |
|
988 |
||
|
1202
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|
989 |
The interrupt-less operation is desirable, because hardware interrupts are not |
|
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|
990 |
conducive in improving the driver's realtime behaviour: Their indeterministic |
|
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|
991 |
incidences contribute to increasing the jitter. Besides, if a realtime |
|
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|
992 |
extension (like RTAI) is used, some additional effort would have to be made to |
|
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|
993 |
prioritize interrupts. |
| 369 | 994 |
|
995 |
\paragraph{Ethernet and EtherCAT Devices}
|
|
996 |
||
| 1095 | 997 |
Another issue lies in the way Linux handles devices of the same type. For |
998 |
example, a PCI\nomenclature{PCI}{Peripheral Component Interconnect, Computer
|
|
999 |
Bus} driver scans the PCI bus for devices it can handle. Then it registers |
|
1000 |
itself as the responsible driver for all of the devices found. The problem is, |
|
1001 |
that an unmodified driver can not be told to ignore a device because it will |
|
1002 |
be used for EtherCAT later. There must be a way to handle multiple devices of |
|
1003 |
the same type, where one is reserved for EtherCAT, while the other is treated |
|
| 369 | 1004 |
as an ordinary Ethernet device. |
1005 |
||
| 1095 | 1006 |
For all this reasons, the author decided that the only acceptable solution is |
1007 |
to modify standard Ethernet drivers in a way that they keep their normal |
|
1008 |
functionality, but gain the ability to treat one or more of the devices as |
|
1009 |
EtherCAT-capable. |
|
| 369 | 1010 |
|
1011 |
Below are the advantages of this solution: |
|
1012 |
||
1013 |
\begin{itemize}
|
|
1014 |
\item No need to tell the standard drivers to ignore certain devices. |
|
1015 |
\item One networking driver for EtherCAT and non-EtherCAT devices. |
|
1016 |
\item No need to implement a network driver from scratch and running |
|
1017 |
into issues, the former developers already solved. |
|
1018 |
\end{itemize}
|
|
1019 |
||
1020 |
The chosen approach has the following disadvantages: |
|
1021 |
||
1022 |
\begin{itemize}
|
|
1023 |
\item The modified driver gets more complicated, as it must handle |
|
1024 |
EtherCAT and non-EtherCAT devices. |
|
1025 |
\item Many additional case differentiations in the driver code. |
|
|
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c75cdcc5ce87
Started to re-write the documentation.
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|
1026 |
\item Changes and bug fixes on the standard drivers have to be ported |
| 369 | 1027 |
to the Ether\-CAT-capable versions from time to time. |
1028 |
\end{itemize}
|
|
1029 |
||
1030 |
%------------------------------------------------------------------------------ |
|
1031 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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|
1032 |
\section{Device Selection}
|
|
c75cdcc5ce87
Started to re-write the documentation.
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|
1033 |
\label{sec:deviceselection}
|
| 369 | 1034 |
|
|
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|
1035 |
After loading the master module, at least one EtherCAT-capable network driver |
|
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|
1036 |
module has to be loaded, that offers its devices to the master (see |
|
1289
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|
1037 |
sec.~\ref{sec:ecdev}. The master module knows the devices to choose from the
|
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
1038 |
module parameters (see sec.~\ref{sec:mastermod}). If the init script is used
|
|
1202
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|
1039 |
to start the master, the drivers and devices to use can be specified in the |
|
1289
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Removed unnecessary modules; renamed references.
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|
1040 |
sysconfig file (see sec.~\ref{sec:sysconfig}).
|
| 369 | 1041 |
|
1042 |
%------------------------------------------------------------------------------ |
|
1043 |
||
|
1203
acb649738601
Some more documentation...
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|
1044 |
\section{EtherCAT Device Interface}
|
| 369 | 1045 |
\label{sec:ecdev}
|
1046 |
\index{Device interface}
|
|
1047 |
||
1048 |
An anticipation to the section about the master module |
|
|
1289
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Removed unnecessary modules; renamed references.
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|
1049 |
(sec.~\ref{sec:mastermod}) has to be made in order to understand the way, a
|
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
1050 |
network device driver module can connect a device to a specific EtherCAT |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
1051 |
master. |
| 369 | 1052 |
|
|
1202
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|
1053 |
The master module provides a ``device interface'' for network device drivers. |
|
91d190223daa
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|
1054 |
To use this interface, a network device driver module must include the header |
|
91d190223daa
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|
1055 |
\textit{devices/ecdev.h}\nomenclature{ecdev}{EtherCAT Device}, coming with the
|
|
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|
1056 |
EtherCAT master code. This header offers a function interface for EtherCAT |
|
91d190223daa
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|
1057 |
devices. All functions of the device interface are named with the prefix |
|
91d190223daa
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|
1058 |
\lstinline+ecdev+. |
|
91d190223daa
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changeset
|
1059 |
|
|
1289
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|
1060 |
The documentation of the device interface can be found in the header file or |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
1061 |
in the appropriate module of the interface documentation (see |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
1062 |
sec.~\ref{sec:gendoc} for generation instructions).
|
|
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|
1063 |
|
| 1296 | 1064 |
% TODO general description of the device interface |
| 369 | 1065 |
|
1066 |
%------------------------------------------------------------------------------ |
|
1067 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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|
1068 |
\section{Patching Network Drivers}
|
| 369 | 1069 |
\label{sec:patching}
|
1070 |
\index{Network drivers}
|
|
1071 |
||
|
1202
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|
1072 |
This section will describe, how to make a standard Ethernet driver |
|
91d190223daa
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|
1073 |
EtherCAT-capable. Unfortunately, there is no standard procedure to enable an |
|
91d190223daa
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changeset
|
1074 |
Ethernet driver for use with the EtherCAT master, but there are a few common |
|
91d190223daa
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|
1075 |
techniques. |
| 369 | 1076 |
|
1077 |
\begin{enumerate}
|
|
|
1202
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|
1078 |
|
|
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|
1079 |
\item A first simple rule is, that \lstinline+netif_*()+ calls must be avoided |
|
91d190223daa
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changeset
|
1080 |
for all EtherCAT devices. As mentioned before, EtherCAT devices have no |
|
91d190223daa
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|
1081 |
connection to the network stack, and therefore must not call its interface |
|
91d190223daa
Next changes for the documentation.
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changeset
|
1082 |
functions. |
|
91d190223daa
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changeset
|
1083 |
|
|
91d190223daa
Next changes for the documentation.
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|
1084 |
\item Another important thing is, that EtherCAT devices should be operated |
|
91d190223daa
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changeset
|
1085 |
without interrupts. So any calls of registering interrupt handlers and enabling |
|
91d190223daa
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|
1086 |
interrupts at hardware level must be avoided, too. |
|
91d190223daa
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|
1087 |
|
|
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Next changes for the documentation.
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|
1088 |
\item The master does not use a new socket buffer for each send operation: |
|
91d190223daa
Next changes for the documentation.
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changeset
|
1089 |
Instead there is a fix one allocated on master initialization. This socket |
|
91d190223daa
Next changes for the documentation.
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changeset
|
1090 |
buffer is filled with an EtherCAT frame with every send operation and passed to |
|
91d190223daa
Next changes for the documentation.
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changeset
|
1091 |
the \lstinline+hard_start_xmit()+ callback. For that it is necessary, that the |
|
91d190223daa
Next changes for the documentation.
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changeset
|
1092 |
socket buffer is not be freed by the network driver as usual. |
|
91d190223daa
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|
1093 |
|
| 369 | 1094 |
\end{enumerate}
|
1095 |
||
|
1202
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changeset
|
1096 |
An Ethernet driver usually handles several Ethernet devices, each described by |
|
91d190223daa
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changeset
|
1097 |
a \lstinline+net_device+ structure with a \lstinline+priv_data+ field to |
|
91d190223daa
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changeset
|
1098 |
attach driver-dependent data to the structure. To distinguish between normal |
|
91d190223daa
Next changes for the documentation.
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changeset
|
1099 |
Ethernet devices and the ones used by EtherCAT masters, the private data |
|
91d190223daa
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diff
changeset
|
1100 |
structure used by the driver could be extended by a pointer, that points to an |
|
91d190223daa
Next changes for the documentation.
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changeset
|
1101 |
\lstinline+ec_device_t+ object returned by \lstinline+ecdev_offer()+ (see |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
1102 |
sec.~\ref{sec:ecdev}) if the device is used by a master and otherwise is zero.
|
|
1202
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|
1103 |
|
|
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|
1104 |
The RealTek RTL-8139 Fast Ethernet driver is a ``simple'' Ethernet driver and |
|
91d190223daa
Next changes for the documentation.
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|
1105 |
can be taken as an example to patch new drivers. The interesting sections can |
|
91d190223daa
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|
1106 |
be found by searching the string ``ecdev" in the file |
|
91d190223daa
Next changes for the documentation.
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|
1107 |
\textit{devices/8139too-2.6.24-ethercat.c}.
|
| 369 | 1108 |
|
1109 |
%------------------------------------------------------------------------------ |
|
1110 |
||
|
1085
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Started to re-write the documentation.
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|
1111 |
\chapter{State Machines}
|
| 369 | 1112 |
\label{sec:fsm}
|
1113 |
\index{FSM}
|
|
1114 |
||
|
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|
1115 |
Many parts of the EtherCAT master are implemented as \textit{finite state
|
|
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|
1116 |
machines} (FSMs\nomenclature{FSM}{Finite State Machine}). Though this leads
|
|
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|
1117 |
to a higher grade of complexity in some aspects, is opens many new |
|
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|
1118 |
possibilities. |
| 369 | 1119 |
|
1120 |
The below short code example exemplary shows how to read all slave |
|
1121 |
states and moreover illustrates the restrictions of ``sequential'' |
|
1122 |
coding: |
|
1123 |
||
|
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|
1124 |
\begin{lstlisting}[gobble=2,language=C,numbers=left]
|
| 369 | 1125 |
ec_datagram_brd(datagram, 0x0130, 2); // prepare datagram |
1126 |
if (ec_master_simple_io(master, datagram)) return -1; |
|
1127 |
slave_states = EC_READ_U8(datagram->data); // process datagram |
|
1128 |
\end{lstlisting}
|
|
1129 |
||
|
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|
1130 |
The \textit{ec\_master\_simple\_io()} function provides a simple interface for
|
|
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|
1131 |
synchronously sending a single datagram and receiving the result\footnote{For
|
|
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|
1132 |
all communication issues have been meanwhile sourced out into state machines, |
|
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|
1133 |
the function is deprecated and stopped existing. Nevertheless it is adequate |
|
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|
1134 |
for showing it's own restrictions.}. Internally, it queues the specified |
|
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|
1135 |
datagram, invokes the \textit{ec\_master\_send\_datagrams()} function to send
|
|
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|
1136 |
a frame with the queued datagram and then waits actively for its reception. |
| 369 | 1137 |
|
|
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|
1138 |
This sequential approach is very simple, reflecting in only three lines of |
|
5b82b6b39c2d
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|
1139 |
code. The disadvantage is, that the master is blocked for the time it waits |
|
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|
1140 |
for datagram reception. There is no difficulty when only one instance is using |
|
5b82b6b39c2d
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|
1141 |
the master, but if more instances want to (synchronously\footnote{At this
|
|
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|
1142 |
time, synchronous master access will be adequate to show the advantages of an |
|
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|
1143 |
FSM. The asynchronous approach will be discussed in sec.~\ref{sec:eoe}}) use
|
|
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|
1144 |
the master, it is inevitable to think about an alternative to the sequential |
|
5b82b6b39c2d
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|
1145 |
model. |
| 369 | 1146 |
|
1147 |
Master access has to be sequentialized for more than one instance |
|
1148 |
wanting to send and receive datagrams synchronously. With the present |
|
1149 |
approach, this would result in having one phase of active waiting for |
|
1150 |
each instance, which would be non-acceptable especially in realtime |
|
1151 |
circumstances, because of the huge time overhead. |
|
1152 |
||
1153 |
A possible solution is, that all instances would be executed |
|
1154 |
sequentially to queue their datagrams, then give the control to the |
|
1155 |
next instance instead of waiting for the datagram reception. Finally, |
|
1156 |
bus IO is done by a higher instance, which means that all queued |
|
1157 |
datagrams are sent and received. The next step is to execute all |
|
1158 |
instances again, which then process their received datagrams and issue |
|
1159 |
new ones. |
|
1160 |
||
1161 |
This approach results in all instances having to retain their state, |
|
1162 |
when giving the control back to the higher instance. It is quite |
|
1163 |
obvious to use a \textit{finite state machine} model in this case.
|
|
1164 |
Section~\ref{sec:fsmtheory} will introduce some of the theory used,
|
|
1165 |
while the listings below show the basic approach by coding the example |
|
1166 |
from above as a state machine: |
|
1167 |
||
|
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|
1168 |
\begin{lstlisting}[gobble=2,language=C,numbers=left]
|
| 369 | 1169 |
// state 1 |
1170 |
ec_datagram_brd(datagram, 0x0130, 2); // prepare datagram |
|
1171 |
ec_master_queue(master, datagram); // queue datagram |
|
1172 |
next_state = state_2; |
|
1173 |
// state processing finished |
|
1174 |
\end{lstlisting}
|
|
1175 |
||
1176 |
After all instances executed their current state and queued their |
|
1177 |
datagrams, these are sent and received. Then the respective next |
|
1178 |
states are executed: |
|
1179 |
||
|
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|
1180 |
\begin{lstlisting}[gobble=2,language=C,numbers=left]
|
| 369 | 1181 |
// state 2 |
1182 |
if (datagram->state != EC_DGRAM_STATE_RECEIVED) {
|
|
1183 |
next_state = state_error; |
|
1184 |
return; // state processing finished |
|
1185 |
} |
|
1186 |
slave_states = EC_READ_U8(datagram->data); // process datagram |
|
1187 |
// state processing finished. |
|
1188 |
\end{lstlisting}
|
|
1189 |
||
|
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|
1190 |
See sec.~\ref{sec:statemodel} for an introduction to the state machine
|
|
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|
1191 |
programming concept used in the master code. |
| 369 | 1192 |
|
1193 |
%------------------------------------------------------------------------------ |
|
1194 |
||
|
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|
1195 |
\section{State Machine Theory}
|
| 369 | 1196 |
\label{sec:fsmtheory}
|
1197 |
\index{FSM!Theory}
|
|
1198 |
||
1199 |
A finite state machine \cite{automata} is a model of behavior with
|
|
1200 |
inputs and outputs, where the outputs not only depend on the inputs, |
|
1201 |
but the history of inputs. The mathematical definition of a finite |
|
1202 |
state machine (or finite automaton) is a six-tuple $(\Sigma, \Gamma, |
|
1203 |
S, s_0, \delta, \omega)$, with |
|
1204 |
||
1205 |
\begin{itemize}
|
|
1206 |
\item the input alphabet $\Sigma$, with $\Sigma \neq |
|
1207 |
\emptyset$, containing all input symbols, |
|
1208 |
\item the output alphabet $\Gamma$, with $\Gamma \neq |
|
1209 |
\emptyset$, containing all output symbols, |
|
1210 |
\item the set of states $S$, with $S \neq \emptyset$, |
|
1211 |
\item the set of initial states $s_0$ with $s_0 \subseteq S, s_0 \neq |
|
1212 |
\emptyset$ |
|
1213 |
\item the transition function $\delta: S \times \Sigma \rightarrow S |
|
1214 |
\times \Gamma$ |
|
1215 |
\item the output function $\omega$. |
|
1216 |
\end{itemize}
|
|
1217 |
||
1218 |
The state transition function $\delta$ is often specified by a |
|
1219 |
\textit{state transition table}, or by a \textit{state transition
|
|
1220 |
diagram}. The transition table offers a matrix view of the state |
|
1221 |
machine behavior (see table~\ref{tab:statetrans}). The matrix rows
|
|
1222 |
correspond to the states ($S = \{s_0, s_1, s_2\}$) and the columns
|
|
1223 |
correspond to the input symbols ($\Gamma = \{a, b, \varepsilon\}$).
|
|
1224 |
The table contents in a certain row $i$ and column $j$ then represent |
|
1225 |
the next state (and possibly the output) for the case, that a certain |
|
1226 |
input symbol $\sigma_j$ is read in the state $s_i$. |
|
1227 |
||
1228 |
\begin{table}[htbp]
|
|
1229 |
\caption{A typical state transition table}
|
|
1230 |
\label{tab:statetrans}
|
|
1231 |
\vspace{2mm}
|
|
1232 |
\centering |
|
1233 |
\begin{tabular}{l|ccc}
|
|
1234 |
& $a$ & $b$ & $\varepsilon$\\ \hline |
|
1235 |
$s_0$ & $s_1$ & $s_1$ & $s_2$\\ |
|
1236 |
$s_1$ & $s_2$ & $s_1$ & $s_0$\\ |
|
1237 |
$s_2$ & $s_0$ & $s_0$ & $s_0$\\ \hline |
|
1238 |
\end{tabular}
|
|
1239 |
\end{table}
|
|
1240 |
||
1241 |
The state diagram for the same example looks like the one in |
|
1242 |
figure~\ref{fig:statetrans}. The states are represented as circles or
|
|
1243 |
ellipses and the transitions are drawn as arrows between them. Close |
|
1244 |
to a transition arrow can be the condition that must be fulfilled to |
|
1245 |
allow the transition. The initial state is marked by a filled black |
|
1246 |
circle with an arrow pointing to the respective state. |
|
1247 |
||
1248 |
\begin{figure}[htbp]
|
|
1249 |
\centering |
|
1250 |
\includegraphics[width=.5\textwidth]{images/statetrans}
|
|
1251 |
\caption{A typical state transition diagram}
|
|
1252 |
\label{fig:statetrans}
|
|
1253 |
\end{figure}
|
|
1254 |
||
1255 |
\paragraph{Deterministic and non-deterministic state machines}
|
|
1256 |
||
1257 |
A state machine can be deterministic, meaning that for one state and |
|
1258 |
input, there is one (and only one) following state. In this case, the |
|
1259 |
state machine has exactly one starting state. Non-deterministic state |
|
1260 |
machines can have more than one transitions for a single state-input |
|
1261 |
combination. There is a set of starting states in the latter case. |
|
1262 |
||
1263 |
\paragraph{Moore and Mealy machines}
|
|
1264 |
||
1265 |
There is a distinction between so-called \textit{Moore machines}, and
|
|
1266 |
\textit{Mealy machines}. Mathematically spoken, the distinction lies
|
|
1267 |
in the output function $\omega$: If it only depends on the current |
|
1268 |
state ($\omega: S \rightarrow \Gamma$), the machine corresponds to the |
|
1269 |
``Moore Model''. Otherwise, if $\omega$ is a function of a state and |
|
1270 |
the input alphabet ($\omega: S \times \Sigma \rightarrow \Gamma$) the |
|
1271 |
state machine corresponds to the ``Mealy model''. Mealy machines are |
|
1272 |
the more practical solution in most cases, because their design allows |
|
1273 |
machines with a minimum number of states. In practice, a mixture of |
|
1274 |
both models is often used. |
|
1275 |
||
1276 |
\paragraph{Misunderstandings about state machines}
|
|
1277 |
||
|
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|
1278 |
There is a phenomenon called ``state explosion'', that is often taken as a |
|
c75cdcc5ce87
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|
1279 |
counter-argument against general use of state machines in complex environments. |
|
c75cdcc5ce87
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changeset
|
1280 |
It has to be mentioned, that this point is misleading~\cite{fsmmis}. State
|
|
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|
1281 |
explosions happen usually as a result of a bad state machine design: Common |
|
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changeset
|
1282 |
mistakes are storing the present values of all inputs in a state, or not |
|
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|
1283 |
dividing a complex state machine into simpler sub state machines. The EtherCAT |
|
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|
1284 |
master uses several state machines, that are executed hierarchically and so |
|
c75cdcc5ce87
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|
1285 |
serve as sub state machines. These are also described below. |
|
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|
1286 |
|
|
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|
1287 |
%------------------------------------------------------------------------------ |
|
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|
1288 |
|
|
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|
1289 |
\section{The Master's State Model}
|
| 369 | 1290 |
\label{sec:statemodel}
|
1291 |
||
1292 |
This section will introduce the techniques used in the master to |
|
1293 |
implement state machines. |
|
1294 |
||
1295 |
\paragraph{State Machine Programming}
|
|
1296 |
||
1297 |
There are certain ways to implement a state machine in \textit{C}
|
|
1298 |
code. An obvious way is to implement the different states and actions |
|
1299 |
by one big case differentiation: |
|
1300 |
||
|
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|
1301 |
\begin{lstlisting}[gobble=2,language=C,numbers=left]
|
| 369 | 1302 |
enum {STATE_1, STATE_2, STATE_3};
|
1303 |
int state = STATE_1; |
|
1304 |
||
1305 |
void state_machine_run(void *priv_data) {
|
|
1306 |
switch (state) {
|
|
1307 |
case STATE_1: |
|
1308 |
action_1(); |
|
1309 |
state = STATE_2; |
|
1310 |
break; |
|
1311 |
case STATE_2: |
|
1312 |
action_2() |
|
1313 |
if (some_condition) state = STATE_1; |
|
1314 |
else state = STATE_3; |
|
1315 |
break; |
|
1316 |
case STATE_3: |
|
1317 |
action_3(); |
|
1318 |
state = STATE_1; |
|
1319 |
break; |
|
1320 |
} |
|
1321 |
} |
|
1322 |
\end{lstlisting}
|
|
1323 |
||
1324 |
For small state machines, this is an option. The disadvantage is, that |
|
1325 |
with an increasing number of states the code soon gets complex and an |
|
1326 |
additional case differentiation is executed each run. Besides, lots of |
|
1327 |
indentation is wasted. |
|
1328 |
||
1329 |
The method used in the master is to implement every state in an own |
|
1330 |
function and to store the current state function with a function |
|
1331 |
pointer: |
|
1332 |
||
|
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|
1333 |
\begin{lstlisting}[gobble=2,language=C,numbers=left]
|
| 369 | 1334 |
void (*state)(void *) = state1; |
1335 |
||
1336 |
void state_machine_run(void *priv_data) {
|
|
1337 |
state(priv_data); |
|
1338 |
} |
|
1339 |
||
1340 |
void state1(void *priv_data) {
|
|
1341 |
action_1(); |
|
1342 |
state = state2; |
|
1343 |
} |
|
1344 |
||
1345 |
void state2(void *priv_data) {
|
|
1346 |
action_2(); |
|
1347 |
if (some_condition) state = state1; |
|
1348 |
else state = state2; |
|
1349 |
} |
|
1350 |
||
1351 |
void state3(void *priv_data) {
|
|
1352 |
action_3(); |
|
1353 |
state = state1; |
|
1354 |
} |
|
1355 |
\end{lstlisting}
|
|
1356 |
||
|
1085
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|
1357 |
In the master code, state pointers of all state machines\footnote{All except
|
|
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|
1358 |
for the EoE state machine, because multiple EoE slaves have to be handled in |
|
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changeset
|
1359 |
parallel. For this reason each EoE handler object has its own state pointer.} |
|
1202
91d190223daa
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|
1360 |
are gathered in a single object of the \lstinline+ec_fsm_master_t+ class. This |
|
91d190223daa
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|
1361 |
is advantageous, because there is always one instance of every state machine |
|
1085
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|
1362 |
available and can be started on demand. |
| 369 | 1363 |
|
1364 |
\paragraph{Mealy and Moore}
|
|
1365 |
||
|
1202
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|
1366 |
If a closer look is taken to the above listing, it can be seen that the |
|
91d190223daa
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|
1367 |
actions executed (the ``outputs'' of the state machine) only depend on the |
|
91d190223daa
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|
1368 |
current state. This accords to the ``Moore'' model introduced in |
|
1289
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|
1369 |
sec.~\ref{sec:fsmtheory}. As mentioned, the ``Mealy'' model offers a higher
|
|
1202
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|
1370 |
flexibility, which can be seen in the listing below: |
| 369 | 1371 |
|
|
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|
1372 |
\begin{lstlisting}[gobble=2,language=C,numbers=left]
|
| 369 | 1373 |
void state7(void *priv_data) {
|
1374 |
if (some_condition) {
|
|
1375 |
action_7a(); |
|
1376 |
state = state1; |
|
1377 |
} |
|
1378 |
else {
|
|
1379 |
action_7b(); |
|
1380 |
state = state8; |
|
1381 |
} |
|
1382 |
} |
|
1383 |
\end{lstlisting}
|
|
1384 |
||
1385 |
\begin{description}
|
|
|
1202
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|
1386 |
|
|
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|
1387 |
\item[\linenum{3} + \linenum{7}] The state function executes the actions
|
|
91d190223daa
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|
1388 |
depending on the state transition, that is about to be done. |
|
91d190223daa
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|
1389 |
|
| 369 | 1390 |
\end{description}
|
1391 |
||
1392 |
The most flexible alternative is to execute certain actions depending |
|
1393 |
on the state, followed by some actions dependent on the state |
|
1394 |
transition: |
|
1395 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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|
1396 |
\begin{lstlisting}[gobble=2,language=C,numbers=left]
|
| 369 | 1397 |
void state9(void *priv_data) {
|
1398 |
action_9(); |
|
1399 |
if (some_condition) {
|
|
1400 |
action_9a(); |
|
1401 |
state = state7; |
|
1402 |
} |
|
1403 |
else {
|
|
1404 |
action_9b(); |
|
1405 |
state = state10; |
|
1406 |
} |
|
1407 |
} |
|
1408 |
\end{lstlisting}
|
|
1409 |
||
|
1202
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|
1410 |
This model is often used in the master. It combines the best aspects of both |
|
91d190223daa
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diff
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|
1411 |
approaches. |
| 369 | 1412 |
|
1413 |
\paragraph{Using Sub State Machines}
|
|
1414 |
||
|
1202
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|
1415 |
To avoid having too much states, certain functions of the EtherCAT master |
|
91d190223daa
Next changes for the documentation.
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diff
changeset
|
1416 |
state machine have been sourced out into sub state machines. This helps to |
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
1417 |
encapsulate the related workflows and moreover avoids the ``state explosion'' |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
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1283
diff
changeset
|
1418 |
phenomenon described in sec.~\ref{sec:fsmtheory}. If the master would instead
|
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
1419 |
use one big state machine, the number of states would be a multiple of the |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
1420 |
actual number. This would increase the level of complexity to a non-manageable |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
1421 |
grade. |
| 369 | 1422 |
|
1423 |
\paragraph{Executing Sub State Machines}
|
|
1424 |
||
1425 |
If a state machine starts to execute a sub state machine, it usually |
|
1426 |
remains in one state until the sub state machine terminates. This is |
|
1427 |
usually done like in the listing below, which is taken out of the |
|
1428 |
slave configuration state machine code: |
|
1429 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
1430 |
\begin{lstlisting}[gobble=2,language=C,numbers=left]
|
|
813
bfc3f1ab52de
Fixed typo SAVEOP -> SAFEOP.
Florian Pose <fp@igh-essen.com>
parents:
487
diff
changeset
|
1431 |
void ec_fsm_slaveconf_safeop(ec_fsm_t *fsm) |
| 369 | 1432 |
{
|
1433 |
fsm->change_state(fsm); // execute state change |
|
1434 |
// sub state machine |
|
1435 |
||
1436 |
if (fsm->change_state == ec_fsm_error) {
|
|
1437 |
fsm->slave_state = ec_fsm_end; |
|
1438 |
return; |
|
1439 |
} |
|
1440 |
||
1441 |
if (fsm->change_state != ec_fsm_end) return; |
|
1442 |
||
1443 |
// continue state processing |
|
1444 |
... |
|
1445 |
\end{lstlisting}
|
|
1446 |
||
1447 |
\begin{description}
|
|
|
1202
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|
1448 |
|
|
91d190223daa
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diff
changeset
|
1449 |
\item[\linenum{3}] \lstinline+change_state+ is the state pointer of the state
|
|
91d190223daa
Next changes for the documentation.
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changeset
|
1450 |
change state machine. The state function, the pointer points on, is |
|
91d190223daa
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1140
diff
changeset
|
1451 |
executed\ldots |
|
91d190223daa
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diff
changeset
|
1452 |
|
|
91d190223daa
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diff
changeset
|
1453 |
\item[\linenum{6}] \ldots either until the state machine terminates with the
|
|
91d190223daa
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diff
changeset
|
1454 |
error state \ldots |
|
91d190223daa
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diff
changeset
|
1455 |
|
|
91d190223daa
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diff
changeset
|
1456 |
\item[\linenum{11}] \ldots or until the state machine terminates in the end
|
|
91d190223daa
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diff
changeset
|
1457 |
state. Until then, the ``higher'' state machine remains in the current state |
|
91d190223daa
Next changes for the documentation.
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diff
changeset
|
1458 |
and executes the sub state machine again in the next cycle. |
|
91d190223daa
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changeset
|
1459 |
|
| 369 | 1460 |
\end{description}
|
1461 |
||
1462 |
\paragraph{State Machine Descriptions}
|
|
1463 |
||
|
1202
91d190223daa
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|
1464 |
The below sections describe every state machine used in the EtherCAT master. |
|
91d190223daa
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diff
changeset
|
1465 |
The textual descriptions of the state machines contain references to the |
|
91d190223daa
Next changes for the documentation.
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diff
changeset
|
1466 |
transitions in the corresponding state transition diagrams, that are marked |
|
91d190223daa
Next changes for the documentation.
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1140
diff
changeset
|
1467 |
with an arrow followed by the name of the successive state. Transitions caused |
|
1306
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
Florian Pose <fp@igh-essen.com>
parents:
1299
diff
changeset
|
1468 |
by trivial error cases (i.\,e.\ no response from slave) are not described |
|
1202
91d190223daa
Next changes for the documentation.
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diff
changeset
|
1469 |
explicitly. These transitions are drawn as dashed arrows in the diagrams. |
|
91d190223daa
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1140
diff
changeset
|
1470 |
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1471 |
%------------------------------------------------------------------------------ |
|
91d190223daa
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diff
changeset
|
1472 |
|
|
91d190223daa
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diff
changeset
|
1473 |
\section{The Master State Machine}
|
|
91d190223daa
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changeset
|
1474 |
\label{sec:fsm-master}
|
|
91d190223daa
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changeset
|
1475 |
\index{FSM!Master}
|
|
91d190223daa
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changeset
|
1476 |
|
|
91d190223daa
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changeset
|
1477 |
The master state machine is executed in the context of the master thread. |
|
91d190223daa
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diff
changeset
|
1478 |
Figure~\ref{fig:fsm-master} shows its transition diagram. Its purposes are:
|
| 369 | 1479 |
|
1480 |
\begin{figure}[htbp]
|
|
1481 |
\centering |
|
|
1202
91d190223daa
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diff
changeset
|
1482 |
\includegraphics[width=\textwidth]{graphs/fsm_master}
|
|
91d190223daa
Next changes for the documentation.
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1140
diff
changeset
|
1483 |
\caption{Transition diagram of the master state machine}
|
|
91d190223daa
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diff
changeset
|
1484 |
\label{fig:fsm-master}
|
| 369 | 1485 |
\end{figure}
|
1486 |
||
1487 |
\begin{description}
|
|
|
1202
91d190223daa
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diff
changeset
|
1488 |
|
|
91d190223daa
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changeset
|
1489 |
\item[Bus monitoring] The bus topology is monitored. If it changes, the bus is |
|
91d190223daa
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diff
changeset
|
1490 |
(re-)scanned. |
|
91d190223daa
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Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1491 |
|
|
91d190223daa
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diff
changeset
|
1492 |
\item[Slave configuration] The application-layer states of the slaves are |
|
91d190223daa
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diff
changeset
|
1493 |
monitored. If a slave is not in the state it supposed to be, the slave is |
|
91d190223daa
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1140
diff
changeset
|
1494 |
(re-)configured. |
|
91d190223daa
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diff
changeset
|
1495 |
|
|
91d190223daa
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diff
changeset
|
1496 |
\item[Request handling] Requests (either originating from the application or |
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1497 |
from external sources) are handled. A request is a job that the master shall |
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1498 |
process asynchronously, for example an SII access, SDO access, or similar. |
| 369 | 1499 |
|
1500 |
\end{description}
|
|
1501 |
||
1502 |
%------------------------------------------------------------------------------ |
|
1503 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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diff
changeset
|
1504 |
\section{The Slave Scan State Machine}
|
| 369 | 1505 |
\label{sec:fsm-scan}
|
1506 |
\index{FSM!Slave Scan}
|
|
1507 |
||
1508 |
The slave scan state machine, which can be seen in |
|
|
1202
91d190223daa
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diff
changeset
|
1509 |
figure~\ref{fig:fsm-slavescan}, leads through the process of reading desired
|
|
91d190223daa
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changeset
|
1510 |
slave information. |
| 369 | 1511 |
|
1512 |
\begin{figure}[htbp]
|
|
1513 |
\centering |
|
|
1202
91d190223daa
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diff
changeset
|
1514 |
\includegraphics[height=.8\textheight]{graphs/fsm_slave_scan}
|
| 369 | 1515 |
\caption{Transition diagram of the slave scan state machine}
|
1516 |
\label{fig:fsm-slavescan}
|
|
1517 |
\end{figure}
|
|
1518 |
||
|
1202
91d190223daa
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changeset
|
1519 |
The scan process includes the following steps: |
|
91d190223daa
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diff
changeset
|
1520 |
|
| 369 | 1521 |
\begin{description}
|
|
1202
91d190223daa
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diff
changeset
|
1522 |
|
|
91d190223daa
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changeset
|
1523 |
\item[Node Address] The node address is set for the slave, so that it can be |
|
91d190223daa
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changeset
|
1524 |
node-addressed for all following operations. |
|
91d190223daa
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diff
changeset
|
1525 |
|
|
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changeset
|
1526 |
\item[AL State] The initial application-layer state is read. |
|
91d190223daa
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changeset
|
1527 |
|
|
91d190223daa
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changeset
|
1528 |
\item[Base Information] Base information (like the number of supported FMMUs) |
|
91d190223daa
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changeset
|
1529 |
is read from the lower physical memory. |
|
91d190223daa
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changeset
|
1530 |
|
|
91d190223daa
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changeset
|
1531 |
\item[Data Link] Information about the physical ports is read. |
|
91d190223daa
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|
1532 |
|
|
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|
1533 |
\item[SII Size] The size of the SII contents is determined to allocate SII |
|
91d190223daa
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changeset
|
1534 |
image memory. |
|
91d190223daa
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changeset
|
1535 |
|
|
91d190223daa
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changeset
|
1536 |
\item[SII Data] The SII contents are read into the master's image. |
|
91d190223daa
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changeset
|
1537 |
|
|
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changeset
|
1538 |
\item[PREOP] If the slave supports CoE, it is set to PREOP state using the |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
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changeset
|
1539 |
State change FSM (see sec.~\ref{sec:fsm-change}) to enable mailbox
|
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1540 |
communication and read the PDO configuration via CoE. |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1541 |
|
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1542 |
\item[PDOs] The PDOs are read via CoE (if supported) using the PDO Reading FSM |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1543 |
(see sec.~\ref{sec:fsm-pdo}). If this is successful, the PDO information from
|
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
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changeset
|
1544 |
the SII (if any) is overwritten. |
| 369 | 1545 |
|
1546 |
\end{description}
|
|
1547 |
||
1548 |
%------------------------------------------------------------------------------ |
|
1549 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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917
diff
changeset
|
1550 |
\section{The Slave Configuration State Machine}
|
| 369 | 1551 |
\label{sec:fsm-conf}
|
1552 |
\index{FSM!Slave Configuration}
|
|
1553 |
||
1554 |
The slave configuration state machine, which can be seen in |
|
|
1202
91d190223daa
Next changes for the documentation.
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changeset
|
1555 |
figure~\ref{fig:fsm-slaveconf}, leads through the process of configuring a
|
|
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diff
changeset
|
1556 |
slave and bringing it to a certain application-layer state. |
| 369 | 1557 |
|
1558 |
\begin{figure}[htbp]
|
|
1559 |
\centering |
|
|
1406
8686c5b3d14b
Clear DC assignment after going to INIT.
Florian Pose <fp@igh-essen.com>
parents:
1399
diff
changeset
|
1560 |
\includegraphics[height=\textheight]{graphs/fsm_slave_conf}
|
| 369 | 1561 |
\caption{Transition diagram of the slave configuration state
|
1562 |
machine} |
|
1563 |
\label{fig:fsm-slaveconf}
|
|
1564 |
\end{figure}
|
|
1565 |
||
1566 |
\begin{description}
|
|
|
1202
91d190223daa
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diff
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|
1567 |
|
|
91d190223daa
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diff
changeset
|
1568 |
\item[INIT] The state change FSM is used to bring the slave to the INIT state. |
|
91d190223daa
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diff
changeset
|
1569 |
|
|
91d190223daa
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diff
changeset
|
1570 |
\item[FMMU Clearing] To avoid that the slave reacts on any process data, the |
|
91d190223daa
Next changes for the documentation.
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1140
diff
changeset
|
1571 |
FMMU configuration are cleared. If the slave does not support FMMUs, this |
|
91d190223daa
Next changes for the documentation.
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1140
diff
changeset
|
1572 |
state is skipped. If INIT is the requested state, the state machine is |
|
91d190223daa
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Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1573 |
finished. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1574 |
|
|
91d190223daa
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diff
changeset
|
1575 |
\item[Mailbox Sync Manager Configuration] If the slaves support mailbox |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1576 |
communication, the mailbox sync managers are configured. Otherwise this state |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1577 |
is skipped. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1578 |
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1579 |
\item[PREOP] The state change FSM is used to bring the slave to PREOP state. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1580 |
If this is the requested state, the state machine is finished. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1581 |
|
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1582 |
\item[SDO Configuration] If there is a slave configuration attached (see |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1583 |
sec.~\ref{sec:masterconfig}), and there are any SDO configurations are
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1584 |
provided by the application, these are sent to the slave. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1585 |
|
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1586 |
\item[PDO Configuration] The PDO configuration state machine is executed to |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1587 |
apply all necessary PDO configurations. |
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1588 |
|
|
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1589 |
\item[PDO Sync Manager Configuration] If any PDO sync managers exist, they are |
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1590 |
configured. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1591 |
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1592 |
\item[FMMU Configuration] If there are FMMUs configurations supplied by the |
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1593 |
application (i.\,e.\ if the application registered PDO entries), they are |
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1594 |
applied. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1595 |
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1596 |
\item[SAFEOP] The state change FSM is used to bring the slave to SAFEOP state. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1597 |
If this is the requested state, the state machine is finished. |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1598 |
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1599 |
\item[OP] The state change FSM is used to bring the slave to OP state. |
|
91d190223daa
Next changes for the documentation.
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1140
diff
changeset
|
1600 |
If this is the requested state, the state machine is finished. |
| 369 | 1601 |
|
1602 |
\end{description}
|
|
1603 |
||
1604 |
%------------------------------------------------------------------------------ |
|
1605 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
1606 |
\section{The State Change State Machine}
|
| 369 | 1607 |
\label{sec:fsm-change}
|
1608 |
\index{FSM!State Change}
|
|
1609 |
||
1610 |
The state change state machine, which can be seen in |
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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1140
diff
changeset
|
1611 |
figure~\ref{fig:fsm-change}, leads through the process of changing a slave's
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
1612 |
application-layer state. This implements the states and transitions described |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
1613 |
in \cite[sec.~6.4.1]{alspec}.
|
| 369 | 1614 |
|
1615 |
\begin{figure}[htbp]
|
|
1616 |
\centering |
|
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
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diff
changeset
|
1617 |
\includegraphics[width=.6\textwidth]{graphs/fsm_change}
|
|
1202
91d190223daa
Next changes for the documentation.
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1140
diff
changeset
|
1618 |
\caption{Transition Diagram of the State Change State Machine}
|
| 369 | 1619 |
\label{fig:fsm-change}
|
1620 |
\end{figure}
|
|
1621 |
||
1622 |
\begin{description}
|
|
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
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1202
diff
changeset
|
1623 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1624 |
\item[Start] The new application-layer state is requested via the ``AL Control |
|
1306
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
Florian Pose <fp@igh-essen.com>
parents:
1299
diff
changeset
|
1625 |
Request'' register (see~\cite[sec. 5.3.1]{alspec}).
|
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1626 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1627 |
\item[Check for Response] Some slave need some time to respond to an AL state |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1628 |
change command, and do not respond for some time. For this case, the command |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1629 |
is issued again, until it is acknowledged. |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1630 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1631 |
\item[Check AL Status] If the AL State change datagram was acknowledged, the |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
1632 |
``AL Control Response'' register (see~\cite[sec. 5.3.2]{alspec}) must be read
|
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
1633 |
out until the slave changes the AL state. |
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1634 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1635 |
\item[AL Status Code] If the slave refused the state change command, the |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1636 |
reason can be read from the ``AL Status Code'' field in the ``AL State |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
1637 |
Changed'' registers (see~\cite[sec. 5.3.3]{alspec}).
|
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1638 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1639 |
\item[Acknowledge State] If the state change was not successful, the master |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1640 |
has to acknowledge the old state by writing to the ``AL Control request'' |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1641 |
register again. |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1642 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1643 |
\item[Check Acknowledge] After sending the acknowledge command, it has to read |
|
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
1644 |
out the ``AL Control Response'' register again. |
| 369 | 1645 |
|
1646 |
\end{description}
|
|
1647 |
||
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1648 |
The ``start\_ack'' state is a shortcut in the state machine for the case, that |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1649 |
the master wants to acknowledge a spontaneous AL state change, that was not |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1650 |
requested. |
|
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
1651 |
|
| 369 | 1652 |
%------------------------------------------------------------------------------ |
1653 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
1654 |
\section{The SII State Machine}
|
| 369 | 1655 |
\label{sec:fsm-sii}
|
1656 |
\index{FSM!SII}
|
|
1657 |
||
1658 |
The SII\index{SII} state machine (shown in figure~\ref{fig:fsm-sii})
|
|
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
1659 |
implements the process of reading or writing SII data via the Slave |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
1660 |
Information Interface described in \cite[sec.~6.4]{dlspec}.
|
| 369 | 1661 |
|
1662 |
\begin{figure}[htbp]
|
|
1663 |
\centering |
|
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
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1202
diff
changeset
|
1664 |
\includegraphics[width=.5\textwidth]{graphs/fsm_sii}
|
|
1202
91d190223daa
Next changes for the documentation.
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1140
diff
changeset
|
1665 |
\caption{Transition Diagram of the SII State Machine}
|
| 369 | 1666 |
\label{fig:fsm-sii}
|
1667 |
\end{figure}
|
|
1668 |
||
|
1203
acb649738601
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parents:
1202
diff
changeset
|
1669 |
This is how the reading part of the state machine works: |
|
1202
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Next changes for the documentation.
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1140
diff
changeset
|
1670 |
|
| 369 | 1671 |
\begin{description}
|
|
1203
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1672 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1673 |
\item[Start Reading] The read request and the requested word address are |
|
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
1674 |
written to the SII attribute. |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1675 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1676 |
\item[Check Read Command] If the SII read request command has been |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1677 |
acknowledged, a timer is started. A datagram is issued, that reads out the SII |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1678 |
attribute for state and data. |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1679 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1680 |
\item[Fetch Data] If the read operation is still busy (the SII is usually |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1681 |
implemented as an E$^2$PROM), the state is read again. Otherwise the data are |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1682 |
copied from the datagram. |
|
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
1683 |
|
| 369 | 1684 |
\end{description}
|
1685 |
||
|
1203
acb649738601
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1202
diff
changeset
|
1686 |
The writing part works nearly similar: |
| 369 | 1687 |
|
1688 |
\begin{description}
|
|
|
1203
acb649738601
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Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1689 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1690 |
\item[Start Writing] A write request, the target address and the data word are |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1691 |
written to the SII attribute. |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1692 |
|
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1693 |
\item[Check Write Command] If the SII write request command has been |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1694 |
acknowledged, a timer is started. A datagram is issued, that reads out the SII |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1695 |
attribute for the state of the write operation. |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
1696 |
|
|
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
1697 |
\item[Wait while Busy] If the write operation is still busy (determined by a |
|
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
1698 |
minimum wait time and the state of the busy flag), the state machine remains in |
|
acb649738601
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parents:
1202
diff
changeset
|
1699 |
this state to avoid that another write operation is issued too early. |
|
acb649738601
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parents:
1202
diff
changeset
|
1700 |
|
| 369 | 1701 |
\end{description}
|
1702 |
||
1703 |
%------------------------------------------------------------------------------ |
|
1704 |
||
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
1705 |
\section{The PDO State Machines}
|
|
1203
acb649738601
Some more documentation...
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|
1706 |
\label{sec:fsm-pdo}
|
|
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1707 |
\index{FSM!PDO}
|
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|
1708 |
|
|
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|
1709 |
The PDO state machines are a set of state machines that read or write the PDO |
|
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|
1710 |
assignment and the PDO mapping via the ``CoE Communication Area'' described in |
|
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|
1711 |
\cite[sec. 5.6.7.4]{alspec}. For the object access, the CANopen over EtherCAT
|
|
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|
1712 |
access primitives are used (see sec.~\ref{sec:coe}), so the slave must support
|
|
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|
1713 |
the CoE mailbox protocol. |
|
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|
1714 |
|
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|
1715 |
\paragraph{PDO Reading FSM} This state machine (fig.~\ref{fig:fsm-pdo-read})
|
|
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|
1716 |
has the purpose to read the complete PDO configuration of a slave. It reads |
|
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|
1717 |
the PDO assignment for each Sync Manager and uses the PDO Entry Reading FSM |
|
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|
1718 |
(fig.~\ref{fig:fsm-pdo-entry-read}) to read the mapping for each assigned PDO.
|
|
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|
1719 |
|
|
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|
1720 |
\begin{figure}[htbp]
|
|
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|
1721 |
\centering |
|
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|
1722 |
\includegraphics[width=.4\textwidth]{graphs/fsm_pdo_read}
|
|
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|
1723 |
\caption{Transition Diagram of the PDO Reading State Machine}
|
|
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1724 |
\label{fig:fsm-pdo-read}
|
|
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|
1725 |
\end{figure}
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|
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|
1726 |
|
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|
1727 |
Basically it reads the every Sync manager's PDO assignment SDO's |
|
1203
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|
1728 |
(\lstinline+0x1C1x+) number of elements to determine the number of assigned |
|
1327
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|
1729 |
PDOs for this sync manager and then reads out the subindices of the SDO to get |
|
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|
1730 |
the assigned PDO's indices. When a PDO index is read, the PDO Entry Reading |
|
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merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
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|
1731 |
FSM is executed to read the PDO's mapped PDO entries. |
|
4d179b06dd3c
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|
1732 |
|
|
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|
1733 |
\paragraph{PDO Entry Reading FSM} This state machine
|
|
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|
1734 |
(fig.~\ref{fig:fsm-pdo-entry-read}) reads the PDO mapping (the PDO entries) of
|
|
4d179b06dd3c
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|
1735 |
a PDO. It reads the respective mapping SDO (\lstinline+0x1600+ -- |
|
1293
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Prcess data; slave configuration + attachment; typos.
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|
1736 |
\lstinline+0x17ff+, or \lstinline+0x1a00+ -- \lstinline+0x1bff+) for the given |
|
1327
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|
1737 |
PDO by reading first the subindex zero (number of elements) to determine the |
|
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|
1738 |
number of mapped PDO entries. After that, each subindex is read to get the |
|
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|
1739 |
mapped PDO entry index, subindex and bit size. |
|
1203
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|
1740 |
|
|
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|
1741 |
\begin{figure}[htbp]
|
|
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|
1742 |
\centering |
|
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|
1743 |
\includegraphics[width=.4\textwidth]{graphs/fsm_pdo_entry_read}
|
|
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|
1744 |
\caption{Transition Diagram of the PDO Entry Reading State Machine}
|
|
1204
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|
1745 |
\label{fig:fsm-pdo-entry-read}
|
|
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|
1746 |
\end{figure}
|
|
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|
1747 |
|
|
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|
1748 |
\begin{figure}[htbp]
|
|
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|
1749 |
\centering |
|
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|
1750 |
\includegraphics[width=.9\textwidth]{graphs/fsm_pdo_conf}
|
|
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|
1751 |
\caption{Transition Diagram of the PDO Configuration State Machine}
|
|
1204
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Removed examples; fixed undefines references; preliminary version.
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|
1752 |
\label{fig:fsm-pdo-conf}
|
|
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|
1753 |
\end{figure}
|
|
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|
1754 |
|
|
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|
1755 |
\begin{figure}[htbp]
|
|
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|
1756 |
\centering |
|
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|
1757 |
\includegraphics[width=.4\textwidth]{graphs/fsm_pdo_entry_conf}
|
|
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|
1758 |
\caption{Transition Diagram of the PDO Entry Configuration State Machine}
|
|
1204
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Removed examples; fixed undefines references; preliminary version.
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|
1759 |
\label{fig:fsm-pdo-entry-conf}
|
|
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|
1760 |
\end{figure}
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|
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|
1761 |
|
|
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|
1762 |
%------------------------------------------------------------------------------ |
|
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|
1763 |
|
|
1085
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Started to re-write the documentation.
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|
1764 |
\chapter{Mailbox Protocol Implementations}
|
| 369 | 1765 |
\index{Mailbox}
|
1766 |
||
1767 |
The EtherCAT master implements the EoE and the CoE mailbox |
|
1768 |
protocols. See the below section for details. |
|
1769 |
||
1770 |
%------------------------------------------------------------------------------ |
|
1771 |
||
|
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|
1772 |
\section{Ethernet over EtherCAT (EoE)}
|
|
1269
fe4688f2c9e7
sec:ecrt is a chapter; sec:eoeimp -> sec:eoe, ...
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|
1773 |
\label{sec:eoe}
|
| 369 | 1774 |
\index{EoE}
|
1775 |
||
|
1306
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|
1776 |
The EtherCAT master implements the |
|
1327
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|
1777 |
Ethernet over EtherCAT\nomenclature{EoE}{Ethernet over EtherCAT, Mailbox
|
|
1306
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|
1778 |
Protocol} mailbox protocol~\cite[sec.~5.7]{alspec} to enable the tunneling of
|
|
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|
1779 |
Ethernet frames to special slaves, that can either have physical Ethernet |
|
a27c839d043b
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|
1780 |
ports to forward the frames to, or have an own IP stack to receive the frames. |
| 369 | 1781 |
|
1782 |
\paragraph{Virtual Network Interfaces}
|
|
1783 |
||
|
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|
1784 |
The master creates a virtual EoE network interface for every EoE-capable |
|
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1785 |
slave. These interfaces are called either |
|
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|
1786 |
|
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|
1787 |
\begin{description}
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|
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1788 |
|
|
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|
1789 |
\item[eoeXsY] for a slave without an alias address (see |
|
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|
1790 |
sec.~\ref{sec:ethercat-alias}), where X is the master index and Y is the
|
|
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|
1791 |
slave's ring position, or |
|
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1792 |
|
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1793 |
\item[eoeXaY] for a slave with a non-zero alias address, where X is the master |
|
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1794 |
index and Y is the decimal alias address. |
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1795 |
|
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1796 |
\end{description}
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1797 |
|
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1798 |
Frames sent to these interfaces are forwarded to the associated slaves by the |
|
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1799 |
master. Frames, that are received by the slaves, are fetched by the master and |
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|
1800 |
forwarded to the virtual interfaces. |
| 369 | 1801 |
|
1802 |
This bears the following advantages: |
|
1803 |
||
1804 |
\begin{itemize}
|
|
|
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1805 |
|
| 369 | 1806 |
\item Flexibility: The user can decide, how the EoE-capable slaves are |
|
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|
1807 |
interconnected with the rest of the world. |
|
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1808 |
|
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1809 |
\item Standard tools can be used to monitor the EoE activity and to configure |
|
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1810 |
the EoE interfaces. |
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1811 |
|
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1812 |
\item The Linux kernel's layer-2-bridging implementation (according to the |
|
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1813 |
IEEE 802.1D MAC Bridging standard) can be used natively to bridge Ethernet |
|
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1814 |
traffic between EoE-capable slaves. |
|
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1815 |
|
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1816 |
\item The Linux kernel's network stack can be used to route packets between |
|
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1817 |
EoE-capable slaves and to track security issues, just like having physical |
|
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|
1818 |
network interfaces. |
|
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|
1819 |
|
| 369 | 1820 |
\end{itemize}
|
1821 |
||
1822 |
\paragraph{EoE Handlers}
|
|
1823 |
||
|
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1824 |
The virtual EoE interfaces and the related functionality is encapsulated in |
|
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|
1825 |
the \lstinline+ec_eoe_t+ class. An object of this class is called ``EoE |
|
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1826 |
handler''. For example the master does not create the network interfaces |
|
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directly: This is done inside the constructor of an EoE handler. An EoE |
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handler additionally contains a frame queue. Each time, the kernel passes a |
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1829 |
new socket buffer for sending via the interface's |
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\lstinline+hard_start_xmit()+ callback, the socket buffer is queued for |
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transmission by the EoE state machine (see below). If the queue gets filled |
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up, the passing of new socket buffers is suspended with a call to |
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\lstinline+netif_stop_queue()+. |
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1834 |
|
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1835 |
\paragraph{Creation of EoE Handlers}
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1836 |
|
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1837 |
During bus scanning (see sec.~\ref{sec:fsm-scan}), the master determines the
|
|
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1838 |
supported mailbox protocols foe each slave. This is done by examining the |
|
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``Supported Mailbox Protocols'' mask field at word address 0x001C of the |
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1840 |
SII\index{SII}. If bit 1 is set, the slave supports the EoE protocol. In this
|
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1841 |
case, an EoE handler is created for that slave. |
| 369 | 1842 |
|
1843 |
\paragraph{EoE State Machine}
|
|
1844 |
\index{FSM!EoE}
|
|
1845 |
||
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1846 |
Every EoE handler owns an EoE state machine, that is used to send frames to |
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1847 |
the corresponding slave and receive frames from the it via the EoE |
| 369 | 1848 |
communication primitives. This state machine is showed in |
1849 |
figure~\ref{fig:fsm-eoe}.
|
|
1850 |
||
1851 |
\begin{figure}[htbp]
|
|
1852 |
\centering |
|
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1853 |
\includegraphics[width=.7\textwidth]{images/fsm-eoe} % FIXME
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1854 |
\caption{Transition Diagram of the EoE State Machine}
|
| 369 | 1855 |
\label{fig:fsm-eoe}
|
1856 |
\end{figure}
|
|
1857 |
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1858 |
% FIXME |
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1859 |
|
| 369 | 1860 |
\begin{description}
|
1861 |
\item[RX\_START] The beginning state of the EoE state machine. A |
|
1862 |
mailbox check datagram is sent, to query the slave's mailbox for new |
|
| 379 | 1863 |
frames. $\rightarrow$~RX\_CHECK |
| 369 | 1864 |
|
1865 |
\item[RX\_CHECK] The mailbox check datagram is received. If the |
|
1866 |
slave's mailbox did not contain data, a transmit cycle is started. |
|
| 379 | 1867 |
$\rightarrow$~TX\_START |
| 369 | 1868 |
|
1869 |
If there are new data in the mailbox, a datagram is sent to fetch |
|
| 379 | 1870 |
the new data. $\rightarrow$~RX\_FETCH |
| 369 | 1871 |
|
1872 |
\item[RX\_FETCH] The fetch datagram is received. If the mailbox data |
|
1873 |
do not contain a ``EoE Fragment request'' command, the data are |
|
1874 |
dropped and a transmit sequence is started. |
|
| 379 | 1875 |
$\rightarrow$~TX\_START |
| 369 | 1876 |
|
1877 |
If the received Ethernet frame fragment is the first fragment, a new |
|
1878 |
socket buffer is allocated. In either case, the data are copied into |
|
1879 |
the correct position of the socket buffer. |
|
1880 |
||
1881 |
If the fragment is the last fragment, the socket buffer is forwarded |
|
1882 |
to the network stack and a transmit sequence is started. |
|
| 379 | 1883 |
$\rightarrow$~TX\_START |
| 369 | 1884 |
|
1885 |
Otherwise, a new receive sequence is started to fetch the next |
|
| 379 | 1886 |
fragment. $\rightarrow$~RX\_\-START |
| 369 | 1887 |
|
1888 |
\item[TX\_START] The beginning state of a transmit sequence. It is |
|
|
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|
1889 |
checked, if the transmission queue contains a frame to send. If not, |
| 379 | 1890 |
a receive sequence is started. $\rightarrow$~RX\_START |
| 369 | 1891 |
|
1892 |
If there is a frame to send, it is dequeued. If the queue was |
|
1893 |
inactive before (because it was full), the queue is woken up with a |
|
1894 |
call to \textit{netif\_wake\_queue()}. The first fragment of the
|
|
| 379 | 1895 |
frame is sent. $\rightarrow$~TX\_SENT |
| 369 | 1896 |
|
1897 |
\item[TX\_SENT] It is checked, if the first fragment was sent |
|
1898 |
successfully. If the current frame consists of further fragments, |
|
| 379 | 1899 |
the next one is sent. $\rightarrow$~TX\_SENT |
| 369 | 1900 |
|
1901 |
If the last fragment was sent, a new receive sequence is started. |
|
| 379 | 1902 |
$\rightarrow$~RX\_START |
| 369 | 1903 |
\end{description}
|
1904 |
||
1905 |
\paragraph{EoE Processing}
|
|
1906 |
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1907 |
To execute the EoE state machine of every active EoE handler, there must be a |
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1908 |
cyclic process. The easiest solution would be to execute the EoE state |
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1909 |
machines synchronously with the master state machine (see |
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|
1910 |
sec.~\ref{sec:fsm-master}). This approach has the following disadvantage:
|
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1911 |
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1912 |
Only one EoE fragment could be sent or received every few cycles. This |
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1913 |
causes the data rate to be very low, because the EoE state machines are not |
|
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|
1914 |
executed in the time between the application cycles. Moreover, the data rate |
|
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|
1915 |
would be dependent on the period of the application task. |
|
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1916 |
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1917 |
To overcome this problem, an own cyclic process is needed to asynchronously |
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1918 |
execute the EoE state machines. For that, the master owns a kernel timer, that |
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1919 |
is executed each timer interrupt. This guarantees a constant bandwidth, but |
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1920 |
poses the new problem of concurrent access to the master. The locking |
|
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|
1921 |
mechanisms needed for this are introduced in sec.~\ref{sec:concurr}.
|
| 369 | 1922 |
|
1923 |
\paragraph{Automatic Configuration}
|
|
1924 |
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1925 |
By default, slaves are left in PREOP state, if no configuration is applied. If |
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1926 |
an EoE interface link is set to ``up'', the requested slave's |
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1927 |
application-layer state is automatically set to OP. |
| 369 | 1928 |
|
1929 |
%------------------------------------------------------------------------------ |
|
1930 |
||
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1931 |
\section{CANopen over EtherCAT (CoE)}
|
|
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1932 |
\label{sec:coe}
|
| 369 | 1933 |
\index{CoE}
|
1934 |
||
|
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1935 |
The CANopen over EtherCAT\nomenclature{CoE}{CANopen over EtherCAT, Mailbox
|
|
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1936 |
Protocol} protocol~\cite[sec.~5.6]{alspec} is used to configure slaves and
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1937 |
exchange data objects on application level. |
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1938 |
|
| 1297 | 1939 |
% TODO |
|
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|
1940 |
% |
|
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|
1941 |
% Download / Upload |
|
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|
1942 |
% Expedited / Normal |
|
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|
1943 |
% Segmenting |
|
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|
1944 |
% SDO Info Services |
|
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|
1945 |
% |
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|
1946 |
|
|
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|
1947 |
\ldots |
| 369 | 1948 |
|
|
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|
1949 |
\paragraph{SDO Download State Machine}
|
|
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|
1950 |
|
|
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|
1951 |
The best time to apply SDO configurations is during the slave's PREOP state, |
|
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|
1952 |
because mailbox communication is already possible and slave's application will |
|
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|
1953 |
start with updating input data in the succeeding SAFEOP state. Therefore the |
|
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|
1954 |
SDO configuration has to be part of the slave configuration state machine (see |
|
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|
1955 |
sec.~\ref{sec:fsm-conf}): It is implemented via an SDO download state machine,
|
|
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|
1956 |
that is executed just before entering the slave's SAFEOP state. In this way, |
|
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|
1957 |
it is guaranteed that the SDO configurations are applied each time, the slave |
|
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|
1958 |
is reconfigured. |
| 369 | 1959 |
|
|
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|
1960 |
The transition diagram of the SDO Download state machine can be seen |
| 369 | 1961 |
in figure~\ref{fig:fsm-coedown}.
|
1962 |
||
1963 |
\begin{figure}[htbp]
|
|
1964 |
\centering |
|
|
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1965 |
\includegraphics[width=.9\textwidth]{images/fsm-coedown} % FIXME
|
| 369 | 1966 |
\caption{Transition diagram of the CoE download state machine}
|
1967 |
\label{fig:fsm-coedown}
|
|
1968 |
\end{figure}
|
|
1969 |
||
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1970 |
% FIXME |
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1971 |
|
| 369 | 1972 |
\begin{description}
|
1973 |
\item[START] The beginning state of the CoE download state |
|
|
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|
1974 |
machine. The ``SDO Download Normal Request'' mailbox command is |
| 379 | 1975 |
sent. $\rightarrow$~REQUEST |
| 369 | 1976 |
|
1977 |
\item[REQUEST] It is checked, if the CoE download request has been |
|
1978 |
received by the slave. After that, a mailbox check command is issued |
|
| 379 | 1979 |
and a timer is started. $\rightarrow$~CHECK |
| 369 | 1980 |
|
1981 |
\item[CHECK] If no mailbox data is available, the timer is checked. |
|
1982 |
\begin{itemize}
|
|
|
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|
1983 |
\item If it timed out, the SDO download is aborted. |
| 379 | 1984 |
$\rightarrow$~ERROR |
| 369 | 1985 |
\item Otherwise, the mailbox is queried again. |
| 379 | 1986 |
$\rightarrow$~CHECK |
| 369 | 1987 |
\end{itemize}
|
1988 |
||
1989 |
If the mailbox contains new data, the response is fetched. |
|
| 379 | 1990 |
$\rightarrow$~RESPONSE |
| 369 | 1991 |
|
1992 |
\item[RESPONSE] If the mailbox response could not be fetched, the data |
|
|
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|
1993 |
is invalid, the wrong protocol was received, or a ``Abort SDO |
|
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|
1994 |
Transfer Request'' was received, the SDO download is aborted. |
| 379 | 1995 |
$\rightarrow$~ERROR |
| 369 | 1996 |
|
|
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|
1997 |
If a ``SDO Download Normal Response'' acknowledgement was received, |
|
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|
1998 |
the SDO download was successful. $\rightarrow$~END |
|
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|
1999 |
|
|
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|
2000 |
\item[END] The SDO download was successful. |
|
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|
2001 |
|
|
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|
2002 |
\item[ERROR] The SDO download was aborted due to an error. |
| 369 | 2003 |
|
2004 |
\end{description}
|
|
2005 |
||
2006 |
%------------------------------------------------------------------------------ |
|
2007 |
||
|
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|
2008 |
\section{Vendor specific over EtherCAT (VoE)}
|
|
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|
2009 |
\label{sec:voe}
|
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2010 |
\index{VoE}
|
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2011 |
|
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2012 |
The VoE protocol opens the possibility to implement a vendor-specific mailbox |
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2013 |
communication protocol. VoE mailbox messages are prepended by a VoE header |
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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changeset
|
2014 |
containing a 32-bit vendor ID and a 16-bit vendor-type. There are no more |
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2015 |
constraints regarding this protocol. |
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2016 |
|
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2017 |
The EtherCAT master allows to create multiple VoE handlers per slave |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
2018 |
configuration via the application interface (see chap.~\ref{chap:api}). These
|
|
1270
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2019 |
handlers contain the state machine necessary for the communication via VoE. |
| 1298 | 2020 |
|
2021 |
For more information about using VoE handlers, see sec.~\ref{sec:api-voe} or
|
|
2022 |
the example applications provided in the \textit{examples/} subdirectory.
|
|
|
1270
11f4b6e10d74
Version 1.5.0; VoE documentation.
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|
2023 |
|
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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changeset
|
2024 |
%------------------------------------------------------------------------------ |
|
11f4b6e10d74
Version 1.5.0; VoE documentation.
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changeset
|
2025 |
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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|
2026 |
\chapter{Userspace Interfaces}
|
| 369 | 2027 |
\label{sec:user}
|
|
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c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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|
2028 |
\index{Userspace}
|
|
1202
91d190223daa
Next changes for the documentation.
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|
2029 |
|
|
1203
acb649738601
Some more documentation...
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|
2030 |
For the master runs as a kernel module, accessing it is natively limited to |
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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changeset
|
2031 |
analyzing Syslog messages and controlling using \textit{modutils}.
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2032 |
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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changeset
|
2033 |
It was necessary to implement further interfaces, that make it easier to access |
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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|
2034 |
the master from userspace and allow a finer influence. It should be possible |
|
1203
acb649738601
Some more documentation...
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parents:
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diff
changeset
|
2035 |
to view and to change special parameters at runtime. |
|
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
2036 |
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2037 |
Bus visualization is another point: For development and debugging purposes it |
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2038 |
is necessary to show the connected slaves with a single command, for instance |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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parents:
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changeset
|
2039 |
(see sec.~\ref{sec:tool}).
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2040 |
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2041 |
The application interface has to be available in userspace, to allow userspace |
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2042 |
programs to use EtherCAT master functionality. This was implemented via a |
| 1282 | 2043 |
character device and a userspace library (see sec.~\ref{sec:userlib}).
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2044 |
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2045 |
Another aspect is automatic startup and configuration. The master must be able |
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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diff
changeset
|
2046 |
to automatically start up with a persistent configuration (see |
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2047 |
sec.~\ref{sec:system}).
|
|
1203
acb649738601
Some more documentation...
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parents:
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diff
changeset
|
2048 |
|
|
acb649738601
Some more documentation...
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parents:
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diff
changeset
|
2049 |
A last thing is monitoring EtherCAT communication. For debugging purposes, |
|
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
2050 |
there had to be a way to analyze EtherCAT datagrams. The best way would be |
|
acb649738601
Some more documentation...
Florian Pose <fp@igh-essen.com>
parents:
1202
diff
changeset
|
2051 |
with a popular network analyzer, like Wireshark \cite{wireshark} (the former
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
1270
diff
changeset
|
2052 |
Ethereal) or others (see sec.~\ref{sec:debug}).
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
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changeset
|
2053 |
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
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parents:
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changeset
|
2054 |
This chapter covers all these points and introduces the interfaces and tools |
|
1203
acb649738601
Some more documentation...
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parents:
1202
diff
changeset
|
2055 |
to make all that possible. |
| 369 | 2056 |
|
2057 |
%------------------------------------------------------------------------------ |
|
2058 |
||
|
1087
f1417824cee5
prepared command-line tool.
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parents:
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diff
changeset
|
2059 |
\section{Command-line Tool}
|
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
2060 |
\label{sec:tool}
|
|
1087
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2061 |
|
| 1297 | 2062 |
% TODO --master |
|
1087
f1417824cee5
prepared command-line tool.
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parents:
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diff
changeset
|
2063 |
|
|
1202
91d190223daa
Next changes for the documentation.
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parents:
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changeset
|
2064 |
\subsection{Character Devices}
|
|
1087
f1417824cee5
prepared command-line tool.
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parents:
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diff
changeset
|
2065 |
\label{sec:cdev}
|
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2066 |
|
| 1214 | 2067 |
Each master instance will get a character device as a userspace interface. |
2068 |
The devices are named \textit{/dev/EtherCATx}, where $x \in \{0 \ldots n\}$ is
|
|
2069 |
the index of the master. |
|
2070 |
||
2071 |
\paragraph{Device Node Creation} The character device nodes are automatically
|
|
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2072 |
created, if the \lstinline+udev+ Package is installed. See |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2073 |
sec.~\ref{sec:autonode} for how to install and configure it.
|
|
1087
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2074 |
|
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2075 |
%------------------------------------------------------------------------------ |
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2076 |
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2077 |
\subsection{Setting Alias Addresses}
|
|
1293
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
2078 |
\label{sec:ethercat-alias}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2079 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2080 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_alias}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2081 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2082 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2083 |
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2084 |
\subsection{Displaying the Bus Configuration}
|
|
1293
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
2085 |
\label{sec:ethercat-config}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2086 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2087 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_config}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2088 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2089 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2090 |
|
|
1202
91d190223daa
Next changes for the documentation.
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parents:
1140
diff
changeset
|
2091 |
\subsection{Displaying Process Data}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2092 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2093 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_data}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2094 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2095 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2096 |
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2097 |
\subsection{Setting a Master's Debug Level}
|
|
1399
f79d4bb5b23a
Added debug_level module parameter. debug_level is now unsigned int.
Florian Pose <fp@igh-essen.com>
parents:
1364
diff
changeset
|
2098 |
\label{sec:ethercat-debug}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2099 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2100 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_debug}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2101 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2102 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2103 |
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2104 |
\subsection{Configured Domains}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2105 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2106 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_domains}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2107 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2108 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2109 |
|
| 1423 | 2110 |
\subsection{SDO Access}
|
2111 |
||
2112 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_download}
|
|
2113 |
||
2114 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_upload}
|
|
2115 |
||
2116 |
%------------------------------------------------------------------------------ |
|
2117 |
||
2118 |
\subsection{File-Access over EtherCAT}
|
|
2119 |
||
2120 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_foe_read}
|
|
2121 |
||
2122 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_foe_write}
|
|
2123 |
||
2124 |
%------------------------------------------------------------------------------ |
|
2125 |
||
2126 |
\subsection{Creating Topology Graphs}
|
|
2127 |
||
2128 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_graph}
|
|
2129 |
||
2130 |
%------------------------------------------------------------------------------ |
|
2131 |
||
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2132 |
\subsection{Master and Ethernet Devices}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2133 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2134 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_master}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2135 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2136 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2137 |
|
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
2138 |
\subsection{Sync Managers, PDOs and PDO Entries}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2139 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2140 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_pdos}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2141 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2142 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2143 |
|
| 1423 | 2144 |
\subsection{Register Access}
|
2145 |
||
2146 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_reg_read}
|
|
2147 |
||
2148 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_reg_write}
|
|
2149 |
||
2150 |
%------------------------------------------------------------------------------ |
|
2151 |
||
|
1327
4d179b06dd3c
merge -c1604 branches/stable-1.4: Fixed spelling of EtherCAT terms.
Florian Pose <fp@igh-essen.com>
parents:
1309
diff
changeset
|
2152 |
\subsection{SDO Dictionary}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2153 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2154 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_sdos}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2155 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2156 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2157 |
|
| 1423 | 2158 |
\subsection{SII Access}
|
2159 |
\label{sec:siiaccess}
|
|
2160 |
\index{SII!Access}
|
|
2161 |
||
2162 |
It is possible to directly read or write the complete SII contents of the |
|
2163 |
slaves. This was introduced for the reasons below: |
|
2164 |
||
2165 |
\begin{itemize}
|
|
2166 |
||
2167 |
\item The format of the SII data is still in development and categories can be |
|
2168 |
added in the future. With read and write access, the complete memory contents |
|
2169 |
can be easily backed up and restored. |
|
2170 |
||
2171 |
\item Some SII data fields have to be altered (like the alias address). A quick |
|
2172 |
writing must be possible for that. |
|
2173 |
||
2174 |
\item Through reading access, analyzing category data is possible from |
|
2175 |
userspace. |
|
2176 |
||
2177 |
\end{itemize}
|
|
2178 |
||
2179 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_sii_read}
|
|
2180 |
||
2181 |
Reading out SII data is as easy as other commands. Though the data are in |
|
2182 |
binary format, analysis is easier with a tool like \textit{hexdump}:
|
|
2183 |
||
2184 |
\begin{lstlisting}
|
|
2185 |
$ `\textbf{ethercat sii\_read --position 3 | hexdump}`
|
|
2186 |
0000000 0103 0000 0000 0000 0000 0000 0000 008c |
|
2187 |
0000010 0002 0000 3052 07f0 0000 0000 0000 0000 |
|
2188 |
0000020 0000 0000 0000 0000 0000 0000 0000 0000 |
|
2189 |
... |
|
2190 |
\end{lstlisting}
|
|
2191 |
||
2192 |
Backing up SII contents can easily done with a redirection: |
|
2193 |
||
2194 |
\begin{lstlisting}
|
|
2195 |
$ `\textbf{ethercat sii\_read --position 3 > sii-of-slave3.bin}`
|
|
2196 |
\end{lstlisting}
|
|
2197 |
||
2198 |
To download SII contents to a slave, writing access to the master's character |
|
2199 |
device is necessary (see sec.~\ref{sec:cdev}).
|
|
2200 |
||
2201 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_sii_write}
|
|
2202 |
||
2203 |
\begin{lstlisting}
|
|
2204 |
# `\textbf{ethercat sii\_write --position 3 sii-of-slave3.bin}`
|
|
2205 |
\end{lstlisting}
|
|
2206 |
||
2207 |
The SII contents will be checked for validity and then sent to the slave. The |
|
2208 |
write operation may take a few seconds. |
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2209 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2210 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2211 |
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2212 |
\subsection{Slaves on the Bus}
|
|
1087
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2213 |
|
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2214 |
Slave information can be gathered with the subcommand \lstinline+slaves+: |
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2215 |
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2216 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_slaves}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2217 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2218 |
Below is a typical output: |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2219 |
|
|
1087
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2220 |
\begin{lstlisting}
|
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2221 |
$ `\textbf{ethercat slaves}`
|
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2222 |
0 0:0 PREOP + EK1100 Ethernet Kopplerklemme (2A E-Bus) |
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2223 |
1 5555:0 PREOP + EL3162 2K. Ana. Eingang 0-10V |
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2224 |
2 5555:1 PREOP + EL4102 2K. Ana. Ausgang 0-10V |
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2225 |
3 5555:2 PREOP + EL2004 4K. Dig. Ausgang 24V, 0,5A |
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2226 |
\end{lstlisting}
|
|
f1417824cee5
prepared command-line tool.
Florian Pose <fp@igh-essen.com>
parents:
1086
diff
changeset
|
2227 |
|
| 369 | 2228 |
%------------------------------------------------------------------------------ |
2229 |
||
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2230 |
\subsection{Requesting Application-Layer States}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2231 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2232 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_states}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2233 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2234 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2235 |
|
| 1423 | 2236 |
\subsection{Displaying the Master Version}
|
2237 |
||
2238 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_version}
|
|
2239 |
||
2240 |
%------------------------------------------------------------------------------ |
|
2241 |
||
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2242 |
\subsection{Generating Slave Description XML}
|
|
1140
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2243 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2244 |
\lstinputlisting[basicstyle=\ttfamily\footnotesize]{external/ethercat_xml}
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2245 |
|
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2246 |
%------------------------------------------------------------------------------ |
|
cc779f7d2496
Command-line help in the docs.
Florian Pose <fp@igh-essen.com>
parents:
1107
diff
changeset
|
2247 |
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
1270
diff
changeset
|
2248 |
\section{Userspace Library}
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
1270
diff
changeset
|
2249 |
\label{sec:userlib}
|
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
1270
diff
changeset
|
2250 |
|
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2251 |
The native application interface (see chap.~\ref{chap:api}) resides in
|
| 1282 | 2252 |
kernelspace and hence is only accessible from inside the kernel. To make the |
2253 |
application interface available from userspace programs, a userspace library |
|
2254 |
has been created, that can be linked to programs under the terms and |
|
2255 |
conditions of the LGPL, version 2 \cite{lgpl}.
|
|
2256 |
||
2257 |
The library is named \textit{libethercat}. Its sources reside in the
|
|
2258 |
\textit{lib/} subdirectory and are build by default when using
|
|
2259 |
\lstinline+make+. It is installed in the \textit{lib/} path below the
|
|
2260 |
installation prefix as \textit{libethercat.a} (for static linking),
|
|
2261 |
\textit{libethercat.la} (for the use with \textit{libtool}) and
|
|
2262 |
\textit{libethercat.so} (for dynamic linking).
|
|
2263 |
||
| 1299 | 2264 |
\subsection{Using the Library}
|
| 1282 | 2265 |
|
2266 |
The application interface header \textit{ecrt.h} can be used both in kernel
|
|
2267 |
and in user context. |
|
2268 |
||
2269 |
The following minimal example shows how to build a program with EtherCAT |
|
2270 |
functionality. An entire example can be found in the \textit{examples/user/}
|
|
2271 |
path of the master sources. |
|
2272 |
||
2273 |
\begin{lstlisting}[language=C]
|
|
2274 |
#include <ecrt.h> |
|
2275 |
||
2276 |
int main(void) |
|
2277 |
{
|
|
2278 |
ec_master_t *master = ecrt_request_master(0); |
|
2279 |
||
2280 |
if (!master) |
|
2281 |
return 1; // error |
|
2282 |
||
2283 |
pause(); // wait for signal |
|
2284 |
return 0; |
|
2285 |
} |
|
2286 |
\end{lstlisting}
|
|
2287 |
||
2288 |
The program can be compiled and dynamically linked to the library with the |
|
2289 |
below command: |
|
2290 |
||
2291 |
\begin{lstlisting}
|
|
2292 |
gcc ethercat.c -o ectest -I/opt/etherlab/include \ |
|
2293 |
-L/opt/etherlab/lib -lethercat \ |
|
2294 |
-Wl,--rpath -Wl,/opt/etherlab/lib |
|
2295 |
\end{lstlisting}
|
|
2296 |
||
2297 |
The library can also be linked statically to the program: |
|
2298 |
||
2299 |
\begin{lstlisting}
|
|
2300 |
gcc -static ectest.c -o ectest -I/opt/etherlab/include \ |
|
2301 |
/opt/etherlab/lib/libethercat.a |
|
2302 |
\end{lstlisting}
|
|
2303 |
||
2304 |
\subsection{Implementation}
|
|
2305 |
\label{sec:userimp}
|
|
2306 |
||
2307 |
Basically the kernel API was transferred into userspace via the master |
|
| 1299 | 2308 |
character device (see chap.~\ref{chap:arch}, fig.~\ref{fig:arch} and
|
2309 |
sec.~\ref{sec:cdev}).
|
|
| 1282 | 2310 |
|
2311 |
The function calls of the kernel API are mapped to the userspace via an |
|
2312 |
\lstinline+ioctl()+ interface. Each function has its own \lstinline+ioctl()+ |
|
2313 |
call. The kernel part of the interface calls the according API functions |
|
2314 |
directly, what results in a minimum additional delay (see |
|
2315 |
sec.~\ref{sec:usertiming}).
|
|
2316 |
||
| 1299 | 2317 |
For performance reasons, the actual domain process data (see |
2318 |
sec.~\ref{sec:processdata}) are not copied between kernel and user memory on
|
|
2319 |
every access: Instead, the data are memory-mapped to the userspace |
|
2320 |
application. Once the master is configured and activated, the master module |
|
2321 |
creates one process data memory area spanning all domains and maps it to |
|
2322 |
userspace, so that the application can directly access the process data. As a |
|
2323 |
result, there is no additional delay when accessing process data from |
|
2324 |
userspace. |
|
2325 |
||
2326 |
\paragraph{Kernel/User API Differences} Because of the memory-mapping of the
|
|
2327 |
process data, the memory is managed internally by the library functions. As a |
|
2328 |
result, it is not possible to provide external memory for domains, like in the |
|
2329 |
kernel API. The corresponding functions are only available in kernelspace. |
|
2330 |
This is the only difference when using the application interface in userspace. |
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
1270
diff
changeset
|
2331 |
|
| 1281 | 2332 |
\subsection{Timing}
|
2333 |
\label{sec:usertiming}
|
|
2334 |
||
2335 |
An interesting aspect is the timing of the userspace library calls compared to |
|
2336 |
those of the kernel API. Table~\ref{tab:usertiming} shows the call times and
|
|
2337 |
standard deviancies of typical (and time-critical) API functions measured on |
|
2338 |
an Intel Pentium 4 M CPU with \unit{2.2}{\giga\hertz} and a standard 2.6.26
|
|
2339 |
kernel. |
|
2340 |
||
2341 |
\begin{table}[htbp]
|
|
2342 |
\centering |
|
2343 |
\caption{Application Interface Timing Comparison}
|
|
2344 |
\label{tab:usertiming}
|
|
2345 |
\vspace{2mm}
|
|
2346 |
\begin{tabular}{l|c|c|c|c}
|
|
2347 |
||
2348 |
& |
|
2349 |
\multicolumn{2}{|c}{\textbf{Kernelspace}} &
|
|
2350 |
\multicolumn{2}{|c}{\textbf{Userspace}} \\
|
|
2351 |
||
2352 |
\textbf{Function} &
|
|
2353 |
$\mu(t)$ & |
|
2354 |
$\sigma(t)$ & |
|
2355 |
$\mu(t)$ & |
|
2356 |
$\sigma(t)$ \\ |
|
2357 |
\hline |
|
2358 |
||
2359 |
\lstinline+ecrt_master_receive()+ & |
|
2360 |
\unit{1.1}{\micro\second} &
|
|
2361 |
\unit{0.3}{\micro\second} &
|
|
2362 |
\unit{2.2}{\micro\second} &
|
|
2363 |
\unit{0.5}{\micro\second} \\
|
|
2364 |
||
2365 |
\lstinline+ecrt_domain_process()+ & |
|
2366 |
\unit{<0.1}{\micro\second} &
|
|
2367 |
\unit{<0.1}{\micro\second} &
|
|
2368 |
\unit{1.0}{\micro\second} &
|
|
2369 |
\unit{0.2}{\micro\second} \\
|
|
2370 |
||
2371 |
\lstinline+ecrt_domain_queue()+ & |
|
2372 |
\unit{<0.1}{\micro\second} &
|
|
2373 |
\unit{<0.1}{\micro\second} &
|
|
2374 |
\unit{1.0}{\micro\second} &
|
|
2375 |
\unit{0.1}{\micro\second} \\
|
|
2376 |
||
2377 |
\lstinline+ecrt_master_send()+ & |
|
2378 |
\unit{1.8}{\micro\second} &
|
|
2379 |
\unit{0.2}{\micro\second} &
|
|
2380 |
\unit{2.5}{\micro\second} &
|
|
2381 |
\unit{0.5}{\micro\second} \\
|
|
2382 |
||
2383 |
\end{tabular}
|
|
2384 |
\end{table}
|
|
2385 |
||
| 1282 | 2386 |
The test results show, that for this configuration, the userspace API causes |
2387 |
about \unit{1}{\micro\second} additional delay for each function, compared to
|
|
2388 |
the kernel API. |
|
| 1281 | 2389 |
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
1270
diff
changeset
|
2390 |
%------------------------------------------------------------------------------ |
|
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
1270
diff
changeset
|
2391 |
|
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2392 |
\section{System Integration}
|
| 369 | 2393 |
\label{sec:system}
|
2394 |
||
|
1086
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2395 |
To integrate the EtherCAT master as a service into a running system, it comes |
|
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2396 |
with an init script and a sysconfig file, that are described below. |
|
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2397 |
|
|
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2398 |
\subsection{Init Script}
|
| 369 | 2399 |
\label{sec:init}
|
2400 |
\index{Init script}
|
|
2401 |
||
|
1086
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2402 |
The EtherCAT master init script conforms to the requirements of the ``Linux |
|
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2403 |
Standard Base'' (LSB\index{LSB}, \cite{lsb}). The script is installed to
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2404 |
\textit{etc/init.d/ethercat} below the installation prefix and has to be
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2405 |
copied (or better: linked) to the appropriate location (see |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2406 |
sec.~\ref{sec:installation}), before the master can be inserted as a service.
|
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2407 |
Please note, that the init script depends on the sysconfig file described |
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2408 |
below. |
|
1086
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2409 |
|
|
1306
a27c839d043b
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|
2410 |
To provide service dependencies (i.\,e.\ which services have to be started |
|
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parents:
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|
2411 |
before others) inside the init script code, LSB defines a special comment |
|
a27c839d043b
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parents:
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diff
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|
2412 |
block. System tools can extract this information to insert the EtherCAT init |
|
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|
2413 |
script at the correct place in the startup sequence: |
|
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|
2414 |
|
|
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|
2415 |
\lstinputlisting[firstline=38,lastline=48] |
|
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Doc: Architecture, master module, system integration.
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diff
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|
2416 |
{../script/init.d/ethercat}
|
|
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|
2417 |
|
|
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|
2418 |
\subsection{Sysconfig File}
|
|
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|
2419 |
\label{sec:sysconfig}
|
|
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|
2420 |
\index{Sysconfig file}
|
|
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|
2421 |
|
|
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diff
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|
2422 |
For persistent configuration, the init script uses a sysconfig file installed |
|
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|
2423 |
to \textit{etc/sysconfig/ethercat} (below the installation prefix), that is
|
|
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parents:
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diff
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|
2424 |
mandatory for the init script. The sysconfig file contains all configuration |
|
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Doc: Architecture, master module, system integration.
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parents:
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diff
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|
2425 |
variables needed to operate one or more masters. The documentation is inside |
|
722ead4ecc22
Doc: Architecture, master module, system integration.
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parents:
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|
2426 |
the file and included below: |
|
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diff
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|
2427 |
|
|
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|
2428 |
\lstinputlisting[numbers=left,firstline=9,basicstyle=\ttfamily\scriptsize] |
|
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|
2429 |
{../script/sysconfig/ethercat}
|
|
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|
2430 |
|
|
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|
2431 |
\subsection{Starting the Master as a Service}
|
|
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|
2432 |
\label{sec:service}
|
|
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|
2433 |
\index{Service}
|
|
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|
2434 |
|
|
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|
2435 |
After the init script and the sysconfig file are placed into the right |
|
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|
2436 |
location, the EtherCAT master can be inserted as a service. The different Linux |
|
722ead4ecc22
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diff
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|
2437 |
distributions offer different ways to mark a service for starting and stopping |
|
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|
2438 |
in certain runlevels. For example, SUSE Linux provides the \textit{insserv}
|
|
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|
2439 |
command: |
|
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parents:
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|
2440 |
|
|
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|
2441 |
\begin{lstlisting}
|
|
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changeset
|
2442 |
# `\textbf{insserv ethercat}`
|
| 369 | 2443 |
\end{lstlisting}
|
2444 |
||
2445 |
The init script can also be used for manually starting and stopping |
|
2446 |
the EtherCAT master. It has to be executed with one of the parameters |
|
| 379 | 2447 |
\texttt{start}, \texttt{stop}, \texttt{restart} or \texttt{status}.
|
| 369 | 2448 |
|
|
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Started to re-write the documentation.
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|
2449 |
\begin{lstlisting}[gobble=2]
|
| 379 | 2450 |
# `\textbf{/etc/init.d/ethercat restart}`
|
| 369 | 2451 |
Shutting down EtherCAT master done |
2452 |
Starting EtherCAT master done |
|
2453 |
\end{lstlisting}
|
|
2454 |
||
2455 |
%------------------------------------------------------------------------------ |
|
2456 |
||
|
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New debug interfaces docs.
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|
2457 |
\section{Debug Interfaces}
|
| 369 | 2458 |
\label{sec:debug}
|
|
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New debug interfaces docs.
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|
2459 |
\index{Debug Interfaces}
|
| 369 | 2460 |
|
|
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|
2461 |
EtherCAT buses can always be monitored by inserting a switch between master |
|
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changeset
|
2462 |
and slaves. This allows to connect another PC with a network monitor like |
|
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|
2463 |
Wireshark~\cite{wireshark}, for example.
|
|
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changeset
|
2464 |
|
|
1307
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New debug interfaces docs.
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parents:
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diff
changeset
|
2465 |
For convenience, so-called ``debug interfaces'' are supported. Debug |
|
1308
c8b82c27b6df
Improved new debug interfaces again.
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parents:
1307
diff
changeset
|
2466 |
interfaces are virtual network interfaces allowing to capture EtherCAT traffic |
|
c8b82c27b6df
Improved new debug interfaces again.
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parents:
1307
diff
changeset
|
2467 |
with a network monitor (like Wireshark or tcpdump) running on the master |
|
c8b82c27b6df
Improved new debug interfaces again.
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parents:
1307
diff
changeset
|
2468 |
machine without using external hardware. To use this functionality, the master |
|
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2469 |
sources have to be configured with the \lstinline+--enable-debug-if+ switch |
|
c8b82c27b6df
Improved new debug interfaces again.
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parents:
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diff
changeset
|
2470 |
(see sec.~\ref{sec:installation}).
|
|
1307
45a82ad140f8
New debug interfaces docs.
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parents:
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diff
changeset
|
2471 |
|
|
45a82ad140f8
New debug interfaces docs.
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parents:
1306
diff
changeset
|
2472 |
Every EtherCAT master registers a read-only network interface per attached |
|
1308
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2473 |
physical Ethernet device. The network interfaces are named \textit{ecdbgmX}
|
|
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2474 |
for the main device, and \textit{ecdbgbX} for the backup device (for future
|
|
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2475 |
use), where X is the master index. The below listing shows a debug interface |
|
c8b82c27b6df
Improved new debug interfaces again.
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parents:
1307
diff
changeset
|
2476 |
among some standard network interfaces: |
|
1306
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changeset
|
2477 |
|
|
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merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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changeset
|
2478 |
\begin{lstlisting}
|
|
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changeset
|
2479 |
# `\textbf{ip link}`
|
|
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|
2480 |
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue |
|
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merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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changeset
|
2481 |
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 |
|
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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|
2482 |
4: eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000 |
|
1307
45a82ad140f8
New debug interfaces docs.
Florian Pose <fp@igh-essen.com>
parents:
1306
diff
changeset
|
2483 |
link/ether 00:13:46:3b:ad:d7 brd ff:ff:ff:ff:ff:ff |
|
1308
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2484 |
8: ecdbgm0: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast |
|
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2485 |
qlen 1000 |
|
1306
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merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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changeset
|
2486 |
link/ether 00:04:61:03:d1:01 brd ff:ff:ff:ff:ff:ff |
|
1307
45a82ad140f8
New debug interfaces docs.
Florian Pose <fp@igh-essen.com>
parents:
1306
diff
changeset
|
2487 |
\end{lstlisting}
|
|
45a82ad140f8
New debug interfaces docs.
Florian Pose <fp@igh-essen.com>
parents:
1306
diff
changeset
|
2488 |
|
|
45a82ad140f8
New debug interfaces docs.
Florian Pose <fp@igh-essen.com>
parents:
1306
diff
changeset
|
2489 |
While a debug interface is enabled, all frames sent or received to or from the |
|
45a82ad140f8
New debug interfaces docs.
Florian Pose <fp@igh-essen.com>
parents:
1306
diff
changeset
|
2490 |
physical device are additionally forwarded to the debug interface by the |
|
1308
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2491 |
corresponding master. Network interfaces can be enabled with the below |
|
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2492 |
command: |
|
1306
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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changeset
|
2493 |
|
|
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
1299
diff
changeset
|
2494 |
\begin{lstlisting}
|
|
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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diff
changeset
|
2495 |
# `\textbf{ip link set dev ecdbgm0 up}`
|
|
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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changeset
|
2496 |
\end{lstlisting}
|
|
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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diff
changeset
|
2497 |
|
|
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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diff
changeset
|
2498 |
Please note, that the frame rate can be very high. With an application |
|
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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changeset
|
2499 |
connected, the debug interface can produce thousands of frames per second. |
|
a27c839d043b
merge -r1566:1573 branches/stable-1.4: Documentation.
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parents:
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changeset
|
2500 |
|
| 1309 | 2501 |
\paragraph{Attention} The socket buffers needed for the operation of debug
|
2502 |
interfaces have to be allocated dynamically. Some Linux realtime extensions do |
|
|
1308
c8b82c27b6df
Improved new debug interfaces again.
Florian Pose <fp@igh-essen.com>
parents:
1307
diff
changeset
|
2503 |
not allow this in realtime context! |
| 369 | 2504 |
|
2505 |
%------------------------------------------------------------------------------ |
|
2506 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2507 |
\chapter{Timing Aspects}
|
| 369 | 2508 |
\label{sec:timing}
|
2509 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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parents:
917
diff
changeset
|
2510 |
Although EtherCAT's timing is highly deterministic and therefore timing issues |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2511 |
are rare, there are a few aspects that can (and should be) dealt with. |
| 369 | 2512 |
|
2513 |
%------------------------------------------------------------------------------ |
|
2514 |
||
|
1202
91d190223daa
Next changes for the documentation.
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changeset
|
2515 |
\subsection{Application Interface Profiling}
|
| 369 | 2516 |
\label{sec:timing-profile}
|
|
1204
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
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parents:
1203
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changeset
|
2517 |
\index{Profiling}
|
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
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parents:
1203
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changeset
|
2518 |
% FIXME |
| 369 | 2519 |
|
|
1085
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Started to re-write the documentation.
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parents:
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changeset
|
2520 |
One of the most important timing aspects are the execution times of the |
|
1204
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
Florian Pose <fp@igh-essen.com>
parents:
1203
diff
changeset
|
2521 |
application interface functions, that are called in cyclic context. These |
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2522 |
functions make up an important part of the overall timing of the application. |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2523 |
To measure the timing of the functions, the following code was used: |
| 369 | 2524 |
|
2525 |
\begin{lstlisting}[gobble=2,language=C]
|
|
2526 |
c0 = get_cycles(); |
|
2527 |
ecrt_master_receive(master); |
|
2528 |
c1 = get_cycles(); |
|
2529 |
ecrt_domain_process(domain1); |
|
2530 |
c2 = get_cycles(); |
|
2531 |
ecrt_master_run(master); |
|
2532 |
c3 = get_cycles(); |
|
2533 |
ecrt_master_send(master); |
|
2534 |
c4 = get_cycles(); |
|
2535 |
\end{lstlisting}
|
|
2536 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2537 |
Between each call of an interface function, the CPU timestamp counter is read. |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
917
diff
changeset
|
2538 |
The counter differences are converted to \micro\second\ with help of the |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2539 |
\lstinline+cpu_khz+ variable, that contains the number of increments per |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
917
diff
changeset
|
2540 |
\milli\second. |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2541 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2542 |
For the actual measuring, a system with a \unit{2.0}{\giga\hertz} CPU was used,
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2543 |
that ran the above code in an RTAI thread with a period of |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2544 |
\unit{100}{\micro\second}. The measuring was repeated $n = 100$ times and the
|
|
c75cdcc5ce87
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|
2545 |
results were averaged. These can be seen in table~\ref{tab:profile}.
|
| 369 | 2546 |
|
2547 |
\begin{table}[htpb]
|
|
2548 |
\centering |
|
|
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|
2549 |
\caption{Profiling of an Application Cycle on a \unit{2.0}{\giga\hertz}
|
|
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|
2550 |
Processor} |
| 369 | 2551 |
\label{tab:profile}
|
2552 |
\vspace{2mm}
|
|
2553 |
\begin{tabular}{l|r|r}
|
|
|
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|
2554 |
Element & Mean Duration [\second] & Standard Deviancy [\micro\second] \\ |
| 369 | 2555 |
\hline |
2556 |
\textit{ecrt\_master\_receive()} & 8.04 & 0.48\\
|
|
2557 |
\textit{ecrt\_domain\_process()} & 0.14 & 0.03\\
|
|
2558 |
\textit{ecrt\_master\_run()} & 0.29 & 0.12\\
|
|
2559 |
\textit{ecrt\_master\_send()} & 2.18 & 0.17\\ \hline
|
|
2560 |
Complete Cycle & 10.65 & 0.69\\ \hline |
|
2561 |
\end{tabular}
|
|
2562 |
\end{table}
|
|
2563 |
||
|
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|
2564 |
It is obvious, that the functions accessing hardware make up the |
| 369 | 2565 |
lion's share. The \textit{ec\_master\_receive()} executes the ISR of
|
2566 |
the Ethernet device, analyzes datagrams and copies their contents into |
|
2567 |
the memory of the datagram objects. The \textit{ec\_master\_send()}
|
|
2568 |
assembles a frame out of different datagrams and copies it to the |
|
2569 |
hardware buffers. Interestingly, this makes up only a quarter of the |
|
2570 |
receiving time. |
|
2571 |
||
|
1085
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changeset
|
2572 |
The functions that only operate on the masters internal data structures are |
|
c75cdcc5ce87
Started to re-write the documentation.
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diff
changeset
|
2573 |
very fast ($\Delta t < \unit{1}{\micro\second}$). Interestingly the runtime of
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2574 |
\textit{ec\_domain\_process()} has a small standard deviancy relative to the
|
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2575 |
mean value, while this ratio is about twice as big for |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2576 |
\textit{ec\_master\_run()}: This probably results from the latter function
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2577 |
having to execute code depending on the current state and the different state |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2578 |
functions are more or less complex. |
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2579 |
|
|
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Started to re-write the documentation.
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parents:
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diff
changeset
|
2580 |
For a realtime cycle makes up about \unit{10}{\micro\second}, the theoretical
|
|
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Started to re-write the documentation.
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|
2581 |
frequency can be up to \unit{100}{\kilo\hertz}. For two reasons, this frequency
|
| 369 | 2582 |
keeps being theoretical: |
2583 |
||
2584 |
\begin{enumerate}
|
|
|
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|
2585 |
|
|
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Started to re-write the documentation.
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|
2586 |
\item The processor must still be able to run the operating system between the |
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2587 |
realtime cycles. |
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2588 |
|
|
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Started to re-write the documentation.
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changeset
|
2589 |
\item The EtherCAT frame must be sent and received, before the next realtime |
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2590 |
cycle begins. The determination of the bus cycle time is difficult and covered |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
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|
2591 |
in sec.~\ref{sec:timing-bus}.
|
|
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|
2592 |
|
| 369 | 2593 |
\end{enumerate}
|
2594 |
||
2595 |
%------------------------------------------------------------------------------ |
|
2596 |
||
2597 |
\subsection{Bus Cycle Measuring}
|
|
2598 |
\label{sec:timing-bus}
|
|
2599 |
\index{Bus cycle}
|
|
2600 |
||
| 1297 | 2601 |
For measuring the time, a frame is ``on the wire'', two timestamps must be |
2602 |
taken: |
|
| 369 | 2603 |
|
2604 |
\begin{enumerate}
|
|
| 1297 | 2605 |
|
2606 |
\item The time, the Ethernet hardware begins with physically sending the |
|
2607 |
frame. |
|
2608 |
||
2609 |
\item The time, the frame is completely received by the Ethernet hardware. |
|
2610 |
||
| 369 | 2611 |
\end{enumerate}
|
2612 |
||
2613 |
Both times are difficult to determine. The first reason is, that the |
|
| 1297 | 2614 |
interrupts are disabled and the master is not notified, when a frame is sent |
2615 |
or received (polling would distort the results). The second reason is, that |
|
2616 |
even with interrupts enabled, the time from the event to the notification is |
|
2617 |
unknown. Therefore the only way to confidently determine the bus cycle time is |
|
2618 |
an electrical measuring. |
|
| 369 | 2619 |
|
|
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changeset
|
2620 |
Anyway, the bus cycle time is an important factor when designing realtime |
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
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parents:
1203
diff
changeset
|
2621 |
code, because it limits the maximum frequency for the cyclic task of the |
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
Florian Pose <fp@igh-essen.com>
parents:
1203
diff
changeset
|
2622 |
application. In practice, these timing parameters are highly dependent on the |
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
Florian Pose <fp@igh-essen.com>
parents:
1203
diff
changeset
|
2623 |
hardware and often a trial and error method must be used to determine the |
|
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
Florian Pose <fp@igh-essen.com>
parents:
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changeset
|
2624 |
limits of the system. |
|
1085
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changeset
|
2625 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2626 |
The central question is: What happens, if the cycle frequency is too high? The |
| 1297 | 2627 |
answer is, that the EtherCAT frames that have been sent at the end of the |
2628 |
cycle are not yet received, when the next cycle starts. First this is noticed |
|
2629 |
by \textit{ecrt\_domain\_process()}, because the working counter of the
|
|
2630 |
process data datagrams were not increased. The function will notify the user |
|
2631 |
via Syslog\footnote{To limit Syslog output, a mechanism has been implemented,
|
|
2632 |
that outputs a summarized notification at maximum once a second.}. In this |
|
2633 |
case, the process data keeps being the same as in the last cycle, because it |
|
2634 |
is not erased by the domain. When the domain datagrams are queued again, the |
|
2635 |
master notices, that they are already queued (and marked as sent). The master |
|
2636 |
will mark them as unsent again and output a warning, that datagrams were |
|
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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diff
changeset
|
2637 |
``skipped''. |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2638 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
2639 |
On the mentioned \unit{2.0}{\giga\hertz} system, the possible cycle frequency
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
2640 |
can be up to \unit{25}{\kilo\hertz} without skipped frames. This value can
|
| 1297 | 2641 |
surely be increased by choosing faster hardware. Especially the RealTek |
2642 |
network hardware could be replaced by a faster one. Besides, implementing a |
|
2643 |
dedicated ISR for EtherCAT devices would also contribute to increasing the |
|
2644 |
latency. These are two points on the author's to-do list. |
|
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2645 |
|
|
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Started to re-write the documentation.
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changeset
|
2646 |
%------------------------------------------------------------------------------ |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2647 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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diff
changeset
|
2648 |
\chapter{Installation}
|
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2649 |
\label{sec:installation}
|
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2650 |
\index{Master!Installation}
|
| 369 | 2651 |
|
|
1202
91d190223daa
Next changes for the documentation.
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diff
changeset
|
2652 |
\section{Building the Software}
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2653 |
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2654 |
The current EtherCAT master code is available at~\cite{etherlab} or can be
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2655 |
obtained from the EtherLab CD. The \textit{tar.bz2} file has to be unpacked
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2656 |
with the commands below (or similar): |
| 369 | 2657 |
|
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2658 |
\begin{lstlisting}[gobble=2]
|
|
1202
91d190223daa
Next changes for the documentation.
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diff
changeset
|
2659 |
$ `\textbf{tar xjf ethercat-\masterversion.tar.bz2}`
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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diff
changeset
|
2660 |
$ `\textbf{cd ethercat-\masterversion/}`
|
|
374
e43a29f9079e
Updated documentation concerning autotools/installation.
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371
diff
changeset
|
2661 |
\end{lstlisting}
|
|
e43a29f9079e
Updated documentation concerning autotools/installation.
Florian Pose <fp@igh-essen.com>
parents:
371
diff
changeset
|
2662 |
|
|
e43a29f9079e
Updated documentation concerning autotools/installation.
Florian Pose <fp@igh-essen.com>
parents:
371
diff
changeset
|
2663 |
The tarball was created with GNU Autotools, so the build process |
| 487 | 2664 |
follows the below commands: |
| 369 | 2665 |
|
|
1085
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2666 |
\begin{lstlisting}[gobble=2]
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
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diff
changeset
|
2667 |
$ `\textbf{./configure}`
|
|
91d190223daa
Next changes for the documentation.
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parents:
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diff
changeset
|
2668 |
$ `\textbf{make}`
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
2669 |
$ `\textbf{make modules}`
|
|
374
e43a29f9079e
Updated documentation concerning autotools/installation.
Florian Pose <fp@igh-essen.com>
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changeset
|
2670 |
\end{lstlisting}
|
|
e43a29f9079e
Updated documentation concerning autotools/installation.
Florian Pose <fp@igh-essen.com>
parents:
371
diff
changeset
|
2671 |
|
|
1085
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Started to re-write the documentation.
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changeset
|
2672 |
Table~\ref{tab:config} lists important configuration switches and options.
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2673 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2674 |
\begin{table}
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2675 |
\caption{Configuration options}
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2676 |
\label{tab:config}
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2677 |
\vspace{2mm}
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2678 |
\begin{tabular}{l|p{.3\textwidth}|l}
|
|
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Started to re-write the documentation.
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parents:
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changeset
|
2679 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2680 |
\bf Option/Switch & \bf Description & \bf Default\\\hline |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2681 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2682 |
\lstinline+--prefix+ & Installation prefix & \textit{/opt/etherlab}\\
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2683 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2684 |
\lstinline+--with-linux-dir+ & Linux kernel sources & Use running kernel\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2685 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2686 |
\lstinline+--with-rtai-dir+ & RTAI path (only for RTAI example) & \\ |
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2687 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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changeset
|
2688 |
\hline |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2689 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2690 |
\lstinline+--enable-eoe+ & Enable EoE support & yes\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2691 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
2692 |
\lstinline+--enable-cycles+ & Use CPU timestamp counter. Enable this on Intel |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
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diff
changeset
|
2693 |
architecture to get finer timing calculation. & no\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2694 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2695 |
\lstinline+--enable-debug-if+ & Create a debug interface for each master & no\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2696 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
917
diff
changeset
|
2697 |
\lstinline+--enable-debug-ring+ & Create a debug ring to record frames & no\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2698 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2699 |
\hline |
|
c75cdcc5ce87
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parents:
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diff
changeset
|
2700 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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changeset
|
2701 |
\lstinline+--enable-8139too+ & Build the 8139too driver & yes\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2702 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
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parents:
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diff
changeset
|
2703 |
\lstinline+--with-8139too-kernel+ & 8139too kernel & $\dagger$\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2704 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2705 |
\lstinline+--enable-e100+ & Build the e100 driver & no\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2706 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2707 |
\lstinline+--with-e100-kernel+ & e100 kernel & $\dagger$\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2708 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2709 |
\lstinline+--enable-e1000+ & Enable e1000 driver & no\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2710 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2711 |
\lstinline+--with-e1000-kernel+ & e1000 kernel & $\dagger$\\ |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2712 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2713 |
\end{tabular}
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2714 |
\vspace{2mm}
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2715 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2716 |
\begin{description}
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2717 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2718 |
\item[$\dagger$] If this option is not specified, the kernel version to use is |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2719 |
extracted from the Linux kernel sources. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2720 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2721 |
\end{description}
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2722 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2723 |
\end{table}
|
| 487 | 2724 |
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2725 |
\section{Building the Interface Documentation}
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2726 |
\label{sec:gendoc}
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2727 |
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2728 |
The source code is documented using Doxygen~\cite{doxygen}. To build the HTML
|
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2729 |
documentation, the Doxygen software has to be installed. The below command |
| 1095 | 2730 |
will generate the documents in the subdirectory \textit{doxygen-output}:
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2731 |
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2732 |
\begin{lstlisting}
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2733 |
$ `\textbf{make doc}`
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2734 |
\end{lstlisting}
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2735 |
|
|
1204
4e3e8400c338
Removed examples; fixed undefines references; preliminary version.
Florian Pose <fp@igh-essen.com>
parents:
1203
diff
changeset
|
2736 |
The interface documentation can be viewed by pointing a browser to the file |
|
1293
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
2737 |
\textit{doxygen-output/html/index.html}. The functions and data structures of
|
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
2738 |
the application interface a covered by an own module ``Application |
|
a2a03519ee47
Prcess data; slave configuration + attachment; typos.
Florian Pose <fp@igh-essen.com>
parents:
1292
diff
changeset
|
2739 |
Interface''. |
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2740 |
|
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2741 |
\section{Installing the Software}
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2742 |
|
|
1106
745a0cc03143
Added depmod call to docs.
Florian Pose <fp@igh-essen.com>
parents:
1095
diff
changeset
|
2743 |
The below commands have to be entered as \textit{root}: The first one will
|
|
1275
c9de1c0c1f51
*space without whitespace; licensing; userspace interfaces.
Florian Pose <fp@igh-essen.com>
parents:
1270
diff
changeset
|
2744 |
install the EtherCAT header, init script, sysconfig file and the userspace |
|
1202
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2745 |
tool to the prefix path. The second one will install the kernel modules to the |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2746 |
kernel's modules directory. The final \lstinline+depmod+ call is necessary to |
|
91d190223daa
Next changes for the documentation.
Florian Pose <fp@igh-essen.com>
parents:
1140
diff
changeset
|
2747 |
include the kernel modules into the \textit{modules.dep} file to make it
|
|
1106
745a0cc03143
Added depmod call to docs.
Florian Pose <fp@igh-essen.com>
parents:
1095
diff
changeset
|
2748 |
available to the \lstinline+modprobe+ command, used in the init script. |
| 369 | 2749 |
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2750 |
\begin{lstlisting}
|
|
1106
745a0cc03143
Added depmod call to docs.
Florian Pose <fp@igh-essen.com>
parents:
1095
diff
changeset
|
2751 |
# `\textbf{make install}`
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2752 |
# `\textbf{make modules\_install}`
|
|
1106
745a0cc03143
Added depmod call to docs.
Florian Pose <fp@igh-essen.com>
parents:
1095
diff
changeset
|
2753 |
# `\textbf{depmod}`
|
| 369 | 2754 |
\end{lstlisting}
|
2755 |
||
| 1095 | 2756 |
If the target kernel's modules directory is not under \textit{/lib/modules}, a
|
2757 |
different destination directory can be specified with the \lstinline+DESTDIR+ |
|
2758 |
make variable. For example: |
|
| 487 | 2759 |
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2760 |
\begin{lstlisting}
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2761 |
# `\textbf{make DESTDIR=/vol/nfs/root modules\_install}`
|
| 487 | 2762 |
\end{lstlisting}
|
2763 |
||
2764 |
This command will install the compiled kernel modules to |
|
2765 |
\textit{/vol/nfs/root/lib/modules}, prepended by the kernel release.
|
|
2766 |
||
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2767 |
If the EtherCAT master shall be run as a service\footnote{Even if the EtherCAT
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2768 |
master shall not be loaded on system startup, the use of the init script is |
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2769 |
recommended for manual (un-)loading.} (see sec.~\ref{sec:system}), the init
|
|
1086
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2770 |
script and the sysconfig file have to be copied (or linked) to the appropriate |
|
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2771 |
locations. The below example is suitable for SUSE Linux. It may vary for other |
|
722ead4ecc22
Doc: Architecture, master module, system integration.
Florian Pose <fp@igh-essen.com>
parents:
1085
diff
changeset
|
2772 |
distributions. |
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2773 |
|
| 1107 | 2774 |
% FIXME relative ln -s? |
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2775 |
\begin{lstlisting}
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2776 |
# `\textbf{cd /opt/etherlab}`
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2777 |
# `\textbf{cp etc/sysconfig/ethercat /etc/sysconfig/}`
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2778 |
# `\textbf{ln -s etc/init.d/ethercat /etc/init.d/}`
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2779 |
# `\textbf{insserv ethercat}`
|
|
374
e43a29f9079e
Updated documentation concerning autotools/installation.
Florian Pose <fp@igh-essen.com>
parents:
371
diff
changeset
|
2780 |
\end{lstlisting}
|
|
e43a29f9079e
Updated documentation concerning autotools/installation.
Florian Pose <fp@igh-essen.com>
parents:
371
diff
changeset
|
2781 |
|
|
376
d1441d87f5c1
Documentation: EtherLab-CD; obtaining the DEVICE_INDEX.
Florian Pose <fp@igh-essen.com>
parents:
374
diff
changeset
|
2782 |
Now the sysconfig file \texttt{/etc/sysconfig/ethercat} (see
|
|
1289
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2783 |
sec.~\ref{sec:sysconfig}) has to be customized. The minimal customization is
|
|
5b82b6b39c2d
Removed unnecessary modules; renamed references.
Florian Pose <fp@igh-essen.com>
parents:
1283
diff
changeset
|
2784 |
to set the \lstinline+MASTER0_DEVICE+ variable to the MAC address of the |
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2785 |
Ethernet device to use (or \lstinline+ff:ff:ff:ff:ff:ff+ to use the first |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2786 |
device offered) and selecting the driver(s) to load via the |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2787 |
\lstinline+DEVICE_MODULES+ variable. |
| 369 | 2788 |
|
| 1297 | 2789 |
After the basic configuration is done, the master can be started with the |
2790 |
below command: |
|
| 369 | 2791 |
|
|
1094
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2792 |
\begin{lstlisting}
|
|
eb0258e53236
App interface; doxygen; bib.
Florian Pose <fp@igh-essen.com>
parents:
1087
diff
changeset
|
2793 |
# `\textbf{/etc/init.d/ethercat start}`
|
| 369 | 2794 |
\end{lstlisting}
|
2795 |
||
| 1214 | 2796 |
At this time, the operation of the master can be observed by viewing the |
2797 |
Syslog\index{Syslog} messages, which should look like the ones below. If
|
|
2798 |
EtherCAT slaves are connected to the master's EtherCAT device, the activity |
|
2799 |
indicators should begin to flash. |
|
| 369 | 2800 |
|
2801 |
\begin{lstlisting}[numbers=left]
|
|
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2802 |
EtherCAT: Master driver `\masterversion` |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2803 |
EtherCAT: 1 master waiting for devices. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2804 |
EtherCAT Intel(R) PRO/1000 Network Driver - version 6.0.60-k2 |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2805 |
Copyright (c) 1999-2005 Intel Corporation. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2806 |
PCI: Found IRQ 12 for device 0000:01:01.0 |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2807 |
PCI: Sharing IRQ 12 with 0000:00:1d.2 |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2808 |
PCI: Sharing IRQ 12 with 0000:00:1f.1 |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2809 |
EtherCAT: Accepting device 00:0E:0C:DA:A2:20 for master 0. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2810 |
EtherCAT: Starting master thread. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2811 |
ec_e1000: ec0: e1000_probe: Intel(R) PRO/1000 Network |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2812 |
Connection |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2813 |
ec_e1000: ec0: e1000_watchdog_task: NIC Link is Up 100 Mbps |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2814 |
Full Duplex |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2815 |
EtherCAT: Link state changed to UP. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2816 |
EtherCAT: 7 slave(s) responding. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2817 |
EtherCAT: Slave states: PREOP. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2818 |
EtherCAT: Scanning bus. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2819 |
EtherCAT: Bus scanning completed in 431 ms. |
| 369 | 2820 |
\end{lstlisting}
|
2821 |
||
2822 |
\begin{description}
|
|
|
1085
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2823 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2824 |
\item[\linenum{1} -- \linenum{2}] The master module is loading, and one master
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2825 |
is initialized. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2826 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2827 |
\item[\linenum{3} -- \linenum{8}] The EtherCAT-capable e1000 driver is
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2828 |
loading. The master accepts the device with the address |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2829 |
\lstinline+00:0E:0C:DA:A2:20+. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2830 |
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2831 |
\item[\linenum{9} -- \linenum{16}] The master goes to idle phase, starts its
|
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
parents:
917
diff
changeset
|
2832 |
state machine and begins scanning the bus. |
|
c75cdcc5ce87
Started to re-write the documentation.
Florian Pose <fp@igh-essen.com>
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| 369 | 2834 |
\end{description}
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||
| 1214 | 2836 |
\section{Automatic Device Node Creation}
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\label{sec:autonode}
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|
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||
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The \lstinline+ethercat+ command-line tool (see sec.~\ref{sec:tool})
|
| 1214 | 2840 |
communicates with the master via a character device. The corresponding device |
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nodes are created automatically, if the udev daemon is running. Note, that on |
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|
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some distributions, the \lstinline+udev+ package is not installed by default. |
| 1214 | 2843 |
|
2844 |
The device nodes will be created with mode \lstinline+0660+ and group |
|
| 1292 | 2845 |
\lstinline+root+ by default. If ``normal'' users shall have reading access, a |
2846 |
udev rule file (for example \textit{/etc/udev/rules.d/99-EtherCAT.rules}) has
|
|
2847 |
to be created with the following contents: |
|
| 1214 | 2848 |
|
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\begin{lstlisting}
|
|
2850 |
KERNEL=="EtherCAT[0-9]*", MODE="0664" |
|
2851 |
\end{lstlisting}
|
|
2852 |
||
2853 |
After the udev rule file is created and the EtherCAT master is restarted with |
|
2854 |
\lstinline[breaklines=true]+/etc/init.d/ethercat restart+, the device node |
|
2855 |
will be automatically created with the desired rights: |
|
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||
2857 |
\begin{lstlisting}
|
|
2858 |
# `\textbf{ls -l /dev/EtherCAT0}`
|
|
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crw-rw-r-- 1 root root 252, 0 2008-09-03 16:19 /dev/EtherCAT0 |
|
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\end{lstlisting}
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|
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||
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|
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Now, the \lstinline+ethercat+ tool can be used (see sec.~\ref{sec:tool}) even
|
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|
2863 |
as a non-root user. |
| 1214 | 2864 |
|
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If non-root users shall have writing access, the following udev rule can be |
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merge -r1566:1573 branches/stable-1.4: Documentation.
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used instead: |
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|
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merge -r1566:1573 branches/stable-1.4: Documentation.
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\begin{lstlisting}
|
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|
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KERNEL=="EtherCAT[0-9]*", MODE="0664", GROUP="users" |
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\end{lstlisting}
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|
| 369 | 2872 |
%------------------------------------------------------------------------------ |
2873 |
||
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\begin{thebibliography}{99}
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|
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|
2876 |
\bibitem{etherlab} Ingenieurgemeinschaft IgH: EtherLab -- Open Source Toolkit
|
|
eb0258e53236
App interface; doxygen; bib.
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|
2877 |
for rapid realtime code generation under Linux with Simulink/RTW and EtherCAT |
|
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App interface; doxygen; bib.
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|
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technology. \url{http://etherlab.org/en}, 2008.
|
|
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|
2879 |
|
| 369 | 2880 |
\bibitem{dlspec} IEC 61158-4-12: Data-link Protocol Specification.
|
| 1095 | 2881 |
International Electrotechnical Commission (IEC), 2005. |
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App interface; doxygen; bib.
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|
2882 |
|
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eb0258e53236
App interface; doxygen; bib.
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|
2883 |
\bibitem{alspec} IEC 61158-6-12: Application Layer Protocol Specification.
|
| 1095 | 2884 |
International Electrotechnical Commission (IEC), 2005. |
|
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App interface; doxygen; bib.
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|
2885 |
|
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eb0258e53236
App interface; doxygen; bib.
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|
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\bibitem{gpl} GNU General Public License, Version 2.
|
|
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*space without whitespace; licensing; userspace interfaces.
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|
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\url{http://www.gnu.org/licenses/gpl-2.0.html}. October~15, 2008.
|
|
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*space without whitespace; licensing; userspace interfaces.
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|
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*space without whitespace; licensing; userspace interfaces.
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\bibitem{lgpl} GNU Lesser General Public License, Version 2.1.
|
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*space without whitespace; licensing; userspace interfaces.
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2890 |
\url{http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html}. October~15,
|
|
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*space without whitespace; licensing; userspace interfaces.
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2008. |
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|
2892 |
|
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App interface; doxygen; bib.
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\bibitem{lsb} Linux Standard Base.
|
|
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merge -r1566:1573 branches/stable-1.4: Documentation.
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\url{http://www.linuxfoundation.org/en/LSB}. August~9, 2006.
|
|
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|
2895 |
|
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App interface; doxygen; bib.
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\bibitem{wireshark} Wireshark. \url{http://www.wireshark.org}. 2008.
|
|
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App interface; doxygen; bib.
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|
2897 |
|
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\bibitem{automata} {\it Hopcroft, J.\,E.\ / Ullman, J.\,D.}: Introduction to
|
|
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|
2899 |
Automata Theory, Languages and Computation. Adison-Wesley, Reading, |
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|
2900 |
Mass.~1979. |
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|
2901 |
|
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\bibitem{fsmmis} {\it Wagner, F.\ / Wolstenholme, P.}: State machine
|
|
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App interface; doxygen; bib.
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|
2903 |
misunderstandings. In: IEE journal ``Computing and Control Engineering'', |
|
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App interface; doxygen; bib.
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2904 |
2004. |
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App interface; doxygen; bib.
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2905 |
|
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App interface; doxygen; bib.
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|
2906 |
\bibitem{rtai} RTAI. The RealTime Application Interface for Linux from DIAPM.
|
|
eb0258e53236
App interface; doxygen; bib.
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|
2907 |
\url{http://www.rtai.org}, 2006.
|
|
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App interface; doxygen; bib.
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|
2908 |
|
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App interface; doxygen; bib.
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|
2909 |
\bibitem{doxygen} Doxygen. Source code documentation generator tool.
|
|
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App interface; doxygen; bib.
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|
2910 |
\url{http://www.stack.nl/~dimitri/doxygen}, 2008.
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App interface; doxygen; bib.
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|
2911 |
|
| 369 | 2912 |
\end{thebibliography}
|
2913 |
||
|
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|
2914 |
\printnomenclature |
| 369 | 2915 |
\addcontentsline{toc}{chapter}{\nomname}
|
2916 |
\markleft{\nomname}
|
|
2917 |
||
2918 |
\printindex |
|
2919 |
\markleft{Index}
|
|
2920 |
||
2921 |
%------------------------------------------------------------------------------ |
|
2922 |
||
2923 |
\end{document}
|
|
2924 |
||
2925 |
%------------------------------------------------------------------------------ |