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#!/usr/bin/env python

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# -*- coding: utf-8 -*-

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#This file is part of PLCOpenEditor, a library implementing an IEC 61131-3 editor

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#based on the plcopen standard. 

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#

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#Copyright (C) 2007: Edouard TISSERANT and Laurent BESSARD

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#

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#See COPYING file for copyrights details.

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#

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#This library is free software; you can redistribute it and/or

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#modify it under the terms of the GNU General Public

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#License as published by the Free Software Foundation; either

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#version 2.1 of the License, or (at your option) any later version.

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#

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#This library is distributed in the hope that it will be useful,

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#but WITHOUT ANY WARRANTY; without even the implied warranty of

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#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

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#General Public License for more details.

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#

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#You should have received a copy of the GNU General Public

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#License along with this library; if not, write to the Free Software

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#Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

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from threading import Lock, Timer

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from time import time as gettime

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import wx

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REFRESH_PERIOD = 0.1        # Minimum time between 2 refresh

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DEBUG_REFRESH_LOCK = Lock() # Common refresh lock for all debug viewers

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#-------------------------------------------------------------------------------

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#                               Debug Viewer Class

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#-------------------------------------------------------------------------------

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"""

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Class that implements common behavior of every viewers able to display debug 

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values

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"""

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class DebugViewer:

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    def __init__(self, producer, debug, subscribe_tick=True):

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        """

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        Constructor

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        @param producer: Object receiving debug value and dispatching them to

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        consumers

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        @param debug: Flag indicating that Viewer is debugging

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        @param subscribe_tick: Flag indicating that viewer need tick value to

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        synchronize

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        """

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        self.Debug = debug

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        self.SubscribeTick = subscribe_tick

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        # Flag indicating that consumer value update inhibited

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        # (DebugViewer is refreshing)

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        self.Inhibited = False

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        # List of data consumers subscribed to DataProducer

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        self.DataConsumers = {}

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        # Time stamp indicating when last refresh have been initiated

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        self.LastRefreshTime = gettime()

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        # Flag indicating that DebugViewer has acquire common debug lock

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        self.HasAcquiredLock = False

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        # Lock for access to the two preceding variable

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        self.AccessLock = Lock()

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        # Timer to refresh Debug Viewer one last time in the case that a new

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        # value have been received during refresh was inhibited and no one

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        # after refresh was activated

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        self.LastRefreshTimer = None

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        # Lock for access to the timer

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        self.TimerAccessLock = Lock()

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        # Set DataProducer and subscribe tick if needed

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        self.SetDataProducer(producer)

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    def __del__(self):

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        """

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        Destructor

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        """

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        # Unsubscribe all data consumers

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        self.UnsubscribeAllDataConsumers()

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        # Delete reference to DataProducer

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        self.DataProducer = None

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        # Stop last refresh timer

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        if self.LastRefreshTimer is not None:

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            self.LastRefreshTimer.cancel()

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        # Release Common debug lock if DebugViewer has acquired it

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        if self.HasAcquiredLock:

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            DEBUG_REFRESH_LOCK.release()

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    def SetDataProducer(self, producer):

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        """

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        Set Data Producer

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        @param producer: Data Producer

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        """

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        # In the case that tick need to be subscribed and DebugViewer is

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        # debugging

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        if self.SubscribeTick and self.Debug:

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            # Subscribe tick to new data producer

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            if producer is not None:

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                producer.SubscribeDebugIECVariable("__tick__", self)

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            # Unsubscribe tick from old data producer

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            if getattr(self, "DataProducer", None) is not None:

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                self.DataProducer.UnsubscribeDebugIECVariable("__tick__", self)

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        # Save new data producer

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        self.DataProducer = producer

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    def IsDebugging(self):

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        """

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        Get flag indicating if Debug Viewer is debugging

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        @return: Debugging flag

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        """

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        return self.Debug

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    def Inhibit(self, inhibit):

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        """

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        Set consumer value update inhibit flag

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        @param inhibit: Inhibit flag

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        """

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        # Inhibit every data consumers in list

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        for consumer, iec_path in self.DataConsumers.iteritems():

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            consumer.Inhibit(inhibit)

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        # Save inhibit flag

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        self.Inhibited = inhibit

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    def AddDataConsumer(self, iec_path, consumer):

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        """

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        Subscribe data consumer to DataProducer

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        @param iec_path: Path in PLC of variable needed by data consumer

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        @param consumer: Data consumer to subscribe

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        @return: List of value already received [(tick, data),...] (None if

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        subscription failed)

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        """

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        # Return immediately if no DataProducer defined

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        if self.DataProducer is None:

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            return None

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        # Subscribe data consumer to DataProducer

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        result = self.DataProducer.SubscribeDebugIECVariable(

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                        iec_path, consumer)

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        if result is not None and consumer != self:

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            # Store data consumer if successfully subscribed and inform

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            # consumer of variable data type

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            self.DataConsumers[consumer] = iec_path

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            consumer.SetDataType(self.GetDataType(iec_path))

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        return result

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    def RemoveDataConsumer(self, consumer):

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        """

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        Unsubscribe data consumer from DataProducer

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        @param consumer: Data consumer to unsubscribe

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        """

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        # Remove consumer from data consumer list

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        iec_path = self.DataConsumers.pop(consumer, None)

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        # Unsubscribe consumer from DataProducer

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        if iec_path is not None:

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            self.DataProducer.UnsubscribeDebugIECVariable(

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                        iec_path, consumer)

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    def SubscribeAllDataConsumers(self):

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        """

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        Called to Subscribe all data consumers contained in DebugViewer.

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        May be overridden by inherited classes.

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        """

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        # Subscribe tick if needed

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        if self.SubscribeTick and self.Debug and self.DataProducer is not None:

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            self.DataProducer.SubscribeDebugIECVariable("__tick__", self)

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    def UnsubscribeAllDataConsumers(self, tick=True):

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        """

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        Called to Unsubscribe all data consumers.

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        """

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        if self.DataProducer is not None:

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            # Unsubscribe all data consumers in list

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            for consumer, iec_path in self.DataConsumers.iteritems():

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                self.DataProducer.UnsubscribeDebugIECVariable(

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                            iec_path, consumer)

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            # Unscribe tick if needed

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            if self.SubscribeTick and tick and self.Debug:

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                self.DataProducer.UnsubscribeDebugIECVariable("__tick__", self)

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        self.DataConsumers = {}

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    def GetDataType(self, iec_path):

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        """

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        Return variable data type.

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        @param iec_path: Path in PLC of variable

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        @return: variable data type (None if not found)

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        """

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        if self.DataProducer is not None:

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            # Search for variable informations in project compilation files

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            data_type = self.DataProducer.GetDebugIECVariableType(

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                            iec_path.upper())

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            if data_type is not None:

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                return data_type

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            # Search for variable informations in project data

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            infos = self.DataProducer.GetInstanceInfos(iec_path)

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            if infos is not None:

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                return infos["type"]

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        return None

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    def IsNumType(self, data_type):

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        """

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        Indicate if data type given is a numeric data type

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        @param data_type: Data type to test

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        @return: True if data type given is numeric

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        """

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        if self.DataProducer is not None:

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            return self.DataProducer.IsNumType(data_type)

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        return False

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    def ForceDataValue(self, iec_path, value):

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        """

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        Force PLC variable value

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        @param iec_path: Path in PLC of variable to force

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        @param value: Value forced

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        """

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        if self.DataProducer is not None:

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            self.DataProducer.ForceDebugIECVariable(iec_path, value)

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    def ReleaseDataValue(self, iec_path):

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        """

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        Release PLC variable value

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        @param iec_path: Path in PLC of variable to release

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        """

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        if self.DataProducer is not None:

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            self.DataProducer.ReleaseDebugIECVariable(iec_path)

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    def NewDataAvailable(self, tick, *args, **kwargs):

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        """

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        Called by DataProducer for each tick captured in 

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        @param tick: PLC tick captured

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        All other parameters are passed to refresh function 

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        """

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        # Stop last refresh timer

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        self.TimerAccessLock.acquire()

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        if self.LastRefreshTimer is not None:

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            self.LastRefreshTimer.cancel()

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            self.LastRefreshTimer=None

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        self.TimerAccessLock.release()

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        # Only try to refresh DebugViewer if it is visible on screen and not

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        # already refreshing

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        if self.IsShown() and not self.Inhibited:

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            # Try to get acquire common refresh lock if minimum period between

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            # two refresh has expired

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            if gettime() - self.LastRefreshTime > REFRESH_PERIOD and \

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               DEBUG_REFRESH_LOCK.acquire(False):

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                self.StartRefreshing(*args, **kwargs)

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            # If common lock wasn't acquired for any reason, restart last

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            # refresh timer

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            else:

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                self.StartLastRefreshTimer(*args, **kwargs)

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        # In the case that DebugViewer isn't visible on screen and has already

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        # acquired common refresh lock, reset DebugViewer

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        elif not self.IsShown() and self.HasAcquiredLock:

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            DebugViewer.RefreshNewData(self)

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    def ShouldRefresh(self, *args, **kwargs):

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        """

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        Callback function called when last refresh timer expired

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        All parameters are passed to refresh function

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        """

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        # Cancel if DebugViewer is not visible on screen

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        if self and self.IsShown():

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            # Try to acquire common refresh lock

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            if DEBUG_REFRESH_LOCK.acquire(False):

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                self.StartRefreshing(*args, **kwargs)

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            # Restart last refresh timer if common refresh lock acquired failed

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            else:

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                self.StartLastRefreshTimer(*args, **kwargs)

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    def StartRefreshing(self, *args, **kwargs):

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        """

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        Called to initiate a refresh of DebugViewer

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        All parameters are passed to refresh function

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        """

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        # Update last refresh time stamp and flag for common refresh

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        # lock acquired

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        self.AccessLock.acquire()

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        self.HasAcquiredLock = True

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        self.LastRefreshTime = gettime()

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        self.AccessLock.release()

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        # Inhibit data consumer value update

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        self.Inhibit(True)

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        # Initiate DebugViewer refresh

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        wx.CallAfter(self.RefreshNewData, *args, **kwargs)

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    def StartLastRefreshTimer(self, *args, **kwargs):

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        """

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        Called to start last refresh timer for the minimum time between 2

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        refresh

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        All parameters are passed to refresh function

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        """

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        self.TimerAccessLock.acquire()

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        self.LastRefreshTimer = Timer(

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            REFRESH_PERIOD, self.ShouldRefresh, args, kwargs)

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        self.LastRefreshTimer.start()

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        self.TimerAccessLock.release()

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    def RefreshNewData(self, *args, **kwargs):

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        """

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        Called to refresh DebugViewer according to values received by data

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        consumers

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        May be overridden by inherited classes

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        Can receive any parameters depending on what is needed by inherited

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        class 

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        """

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        if self:

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            # Activate data consumer value update

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            self.Inhibit(False)

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            # Release common refresh lock if acquired and update

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            # last refresh time

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            self.AccessLock.acquire()

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            if self.HasAcquiredLock:

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                DEBUG_REFRESH_LOCK.release()

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                self.HasAcquiredLock = False

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            if gettime() - self.LastRefreshTime > REFRESH_PERIOD:

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                self.LastRefreshTime = gettime()

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            self.AccessLock.release()