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doc/manual/connectors.rst
author Andrey Skvortsov <andrej.skvortzov@gmail.com>
Sun, 06 Jan 2019 03:11:39 +0300
changeset 2501 eba2bbb2dd9a
parent 1455 4ba27ed51e48
permissions -rw-r--r--
Make online debug optional

It could be useful for very small targets like Atmega (Arduino) and
for target bring-up there developer want to have running PLC program,
but has not implemented runtime communication yet.


TARGET_DEBUG_AND_RETAIN_DISABLE - completely disable debug and retain
functionality. Previously named TARGET_DEBUG_DISABLE.

TARGET_ONLINE_DEBUG_DISABLE - can be used to enable retain
functionality (no define TARGET_DEBUG_AND_RETAIN_DISABLE is used), but disable
online debug with corresponding RAM/FLASH overhead.

TARGET_LOGGING_DISABLE - disables logging functionality from runtime and PLC program

TARGET_EXT_SYNC_DISABLE - disables PLC program synchronization with
external events. For example, it could be used to synchronize several
PLCs that control motors for different axes.

By default all these options are off.

To test generate program for Generic target, put following files in
project files directory and run build.sh after generating PLC program.
This is very easy to integrate into makefile (Generic target).

[------------- build.sh --------------------------]
files=$(find $PWD/../build -iname '*.c' | grep -v POUS.c)
arm-none-eabi-gcc \
-DTARGET_DEBUG_AND_RETAIN_DISABLE \
-DTARGET_ONLINE_DEBUG_DISABLE \
-DTARGET_LOGGING_DISABLE \
-DTARGET_EXT_SYNC_DISABLE \
-flto -ffunction-sections -fdata-sections -I../../../../matiec/lib/C \
$files \
main.c \
-Wl,--Map=./program.map,--cref \
-nodefaultlibs --specs=nano.specs -Wl,--static -Wl,--gc-section -Wl,--start-group -lc -lm -lnosys -lgcc -Wl,--end-group
[------------------------------------------------]

[------------- main.c --------------------------]
#ifndef TARGET_DEBUG_AND_RETAIN_DISABLE
void Retain(void){}
void InValidateRetainBuffer(void){}
void ValidateRetainBuffer(void){}
#endif

extern void __run(void);
int main(void)
{
for(;;) {
__run();
// sleep common_ticktime__ ns
// add common_ticktime__ ns to __CURRENT_TIME
}
return 0;
}
[------------------------------------------------] 
Beremiz and Beremiz_service connectors 
======================================

To connect a PLC, Beremiz provides 2 types of connectors :
 * a Pyro connector
 * a WAMP connector

To configure the connection, you have to set the *URI_location* in your project Config tab according to this documentation. 

The Pyro connector
----------------------------

Pyro is an advanced and powerful Distributed Object Technology system written entirely in Python.
Beremiz_service spawns a Pyro server, serving a PLCObject (see runtime/PLCObject.py). Therefore, Beremiz acts as a Pyro client.

TODO:: link to PLCObject API documentation

URI_location :
 * LOCAL:// is a facility that starts the PLC service locally and connect Beremiz to it via Pyro.
   This is intended for use in development stage.
 * PYRO://<ip:port> normal connection to a remote PLC. PLC default port is 3000.
 * PYROS://<ip:port> SSL connection to a remote PLC, see below.

more information about Pyro can be found on http://pythonhosted.org//Pyro/1-intro.html

===========================
Setup a Pyro SSL connection
===========================

Pyro v3 has a limited TLS/SSL support based on m2crypto. Pyro v4 had dropped it.
In order to have a full and reliable SSL, we recommand to use a TLS/SSL wrapper as nginx, stub or stunnel.

--------------------
TLS-PSK with stunnel
--------------------

In this example, we setup a simple TLS-PSK connection according to rfc4279.
This ciphersuite avoid the need for public key operations and certificate management.
It is perfect for a performance-constrained environments with limited CPU power as a PLC.


Needed :
 * stunnel >= 5.09

verify openssl support for PSK cipher::

    openssl ciphers -v 'PSK'

----------------------
Client setup (Beremiz)
----------------------

You need to choose an identity for your client, here *client1*.
generate a valid and strong key::

    $ echo client1:$(openssl rand -base64 48) > pskclient1.txt

write a stunnel client configuration file *stunnel-client.conf*::

    output = stunnel-client.log
    client = yes
    
    [beremiz]
    accept = 3002
    connect = [PLC]:3001
    PSKidentity = client1
    PSKsecrets = pskclient1.txt

start stunnel client side::

    stunnel stunnel-client.conf

You could now connect beremiz with classic URI_location = PYRO://127.0.0.1:3002

--------------------
Server setup (PLC)
--------------------

import the client key in a keyfile psk.txt, concatening all client key.

write a stunnel server  configuration file *stunnel-server.conf*::

    output = stunnel-server.log
    
    [beremiz]
    accept = 3001
    connect = 127.0.0.1:3000
    PSKsecrets = psk.txt

start stunnel server side::

    stunnel stunnel-server.conf
    
more documentation on stunnel http://www.stunnel.org/docs.html

The WAMP connector
------------------

WAMP is an open standard WebSocket subprotocol that provides two application messaging 
patterns in one unified protocol: Remote Procedure Calls + Publish & Subscribe.

Beremiz WAMP connector implementation uses Autobahn and crossbar.

URI_location :
	* WAMP://127.0.0.1:8888#Automation#2534667845

more information about WAMP can be found on http://wamp.ws/
beremiz