beremiz

Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

2018-08-24, Andrey Skvortsov
96ca6b056c55
Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

traceback:
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1433, in OnPouSelectedChanged
window.RefreshView()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 837, in RefreshView
self.RefreshProcessVariables()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 886, in RefreshProcessVariables
slaves = self.Controler.GetSlaves(**self.CurrentNodesFilter)
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/EthercatMaster.py", line 341, in GetSlaves
for slave in self.Config.getConfig().getSlave():
:_'lxml.etree._Element'_object_has_no_attribute_'getSlave'

Steps to reproduce problem:

- Add new EtherCAT master
- Add new EthercatNode to the master
- double click on


Revert commit "Dirty fix for error '_object_has_no_attribute_'getSlave' in EtherCAT extension"
[a3ac46366b86a0b237dac93be6b2281ac70b98a8].

The problem was that XML elements (proxy object) in some cases were created using custom XML
classes constructors and lxml.etree.Element() call and live python
patching. This causes that lxml backend doesn't know that custom python class
should be used for these XML elements.
Proxy object can be move/deleted and recreated by lxml
backend at any point in time or this can be done in python by copy/deepcopy operations.
If this happens, then newly created
proxy elements are using default class lxml.etree._Element. And all
custom functionality is lost.

All created XML elements should be always created through corresponding
parser and class lookup callback done by lxml backend.
It's described in more details in lxml documentation:
https://lxml.de/element_classes.html
<?xml version='1.0' encoding='utf-8'?>
<project xmlns:ns1="http://www.plcopen.org/xml/tc6_0201" xmlns:xhtml="http://www.w3.org/1999/xhtml" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.plcopen.org/xml/tc6_0201">
<fileHeader companyName="Unknown" productName="Unnamed" productVersion="1" creationDateTime="2018-07-28T02:24:08"/>
<contentHeader name="BACnet" modificationDateTime="2018-07-29T01:54:59">
<coordinateInfo>
<fbd>
<scaling x="0" y="0"/>
</fbd>
<ld>
<scaling x="0" y="0"/>
</ld>
<sfc>
<scaling x="0" y="0"/>
</sfc>
</coordinateInfo>
</contentHeader>
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<dataTypes/>
<pous>
<pou name="program0" pouType="program">
<interface>
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<variable name="EnergyCounter" address="%MD0.2.0">
<type>
<REAL/>
</type>
</variable>
<variable name="Temperature" address="%ID0.0.0">
<type>
<REAL/>
</type>
</variable>
<variable name="Humidity" address="%ID0.0.1">
<type>
<REAL/>
</type>
</variable>
</localVars>
<localVars>
<variable name="TempSimulation">
<type>
<derived name="Simulator"/>
</type>
</variable>
<variable name="HumiditySimulation">
<type>
<derived name="Simulator"/>
</type>
</variable>
</localVars>
<localVars>
<variable name="TemperatureSetPoint" address="%QD0.1.0">
<type>
<REAL/>
</type>
</variable>
<variable name="ControlDisable" address="%QX0.4.2">
<type>
<BOOL/>
</type>
</variable>
<variable name="Heater" address="%IX0.3.0">
<type>
<BOOL/>
</type>
</variable>
<variable name="Cooler" address="%IX0.3.1">
<type>
<BOOL/>
</type>
</variable>
</localVars>
</interface>
<body>
<FBD>
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<position x="299" y="521"/>
<connectionPointOut>
<relPosition x="105" y="15"/>
</connectionPointOut>
<expression>EnergyCounter</expression>
</inVariable>
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</outVariable>
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<outputVariables>
<variable formalParameter="OUT">
<connectionPointOut>
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</connectionPointOut>
</variable>
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</block>
<inVariable localId="4" executionOrderId="0" height="30" width="105" negated="false">
<position x="296" y="570"/>
<connectionPointOut>
<relPosition x="105" y="15"/>
</connectionPointOut>
<expression>0.00131</expression>
</inVariable>
<comment localId="5" height="67" width="229">
<position x="27" y="525"/>
<content>
<xhtml:p><![CDATA[Always consume some energy]]></xhtml:p>
</content>
</comment>
<block localId="6" typeName="Simulator" instanceName="TempSimulation" executionOrderId="0" height="115" width="134">
<position x="188" y="661"/>
<inputVariables>
<variable formalParameter="MinVal">
<connectionPointIn>
<relPosition x="0" y="35"/>
<connection refLocalId="8">
<position x="188" y="696"/>
<position x="138" y="696"/>
</connection>
</connectionPointIn>
</variable>
<variable formalParameter="MaxVal">
<connectionPointIn>
<relPosition x="0" y="66"/>
<connection refLocalId="9">
<position x="188" y="727"/>
<position x="138" y="727"/>
</connection>
</connectionPointIn>
</variable>
<variable formalParameter="PeriodSeconds">
<connectionPointIn>
<relPosition x="0" y="97"/>
<connection refLocalId="10">
<position x="188" y="758"/>
<position x="138" y="758"/>
</connection>
</connectionPointIn>
</variable>
</inputVariables>
<inOutVariables/>
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<variable formalParameter="Out">
<connectionPointOut>
<relPosition x="134" y="35"/>
</connectionPointOut>
</variable>
</outputVariables>
</block>
<outVariable localId="7" executionOrderId="0" height="30" width="92" negated="false">
<position x="421" y="681"/>
<connectionPointIn>
<relPosition x="0" y="15"/>
<connection refLocalId="6" formalParameter="Out">
<position x="421" y="696"/>
<position x="322" y="696"/>
</connection>
</connectionPointIn>
<expression>Temperature</expression>
</outVariable>
<inVariable localId="8" executionOrderId="0" height="30" width="105" negated="false">
<position x="33" y="681"/>
<connectionPointOut>
<relPosition x="105" y="15"/>
</connectionPointOut>
<expression>18.0</expression>
</inVariable>
<inVariable localId="9" executionOrderId="0" height="30" width="105" negated="false">
<position x="33" y="712"/>
<connectionPointOut>
<relPosition x="105" y="15"/>
</connectionPointOut>
<expression>30.0</expression>
</inVariable>
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<position x="33" y="743"/>
<connectionPointOut>
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</connectionPointOut>
<expression>120</expression>
</inVariable>
<block localId="11" typeName="Simulator" instanceName="HumiditySimulation" executionOrderId="0" height="115" width="134">
<position x="185" y="803"/>
<inputVariables>
<variable formalParameter="MinVal">
<connectionPointIn>
<relPosition x="0" y="35"/>
<connection refLocalId="13">
<position x="185" y="838"/>
<position x="135" y="838"/>
</connection>
</connectionPointIn>
</variable>
<variable formalParameter="MaxVal">
<connectionPointIn>
<relPosition x="0" y="66"/>
<connection refLocalId="14">
<position x="185" y="869"/>
<position x="135" y="869"/>
</connection>
</connectionPointIn>
</variable>
<variable formalParameter="PeriodSeconds">
<connectionPointIn>
<relPosition x="0" y="97"/>
<connection refLocalId="15">
<position x="185" y="900"/>
<position x="135" y="900"/>
</connection>
</connectionPointIn>
</variable>
</inputVariables>
<inOutVariables/>
<outputVariables>
<variable formalParameter="Out">
<connectionPointOut>
<relPosition x="134" y="35"/>
</connectionPointOut>
</variable>
</outputVariables>
</block>
<outVariable localId="12" executionOrderId="0" height="30" width="92" negated="false">
<position x="418" y="823"/>
<connectionPointIn>
<relPosition x="0" y="15"/>
<connection refLocalId="11" formalParameter="Out">
<position x="418" y="838"/>
<position x="319" y="838"/>
</connection>
</connectionPointIn>
<expression>Humidity</expression>
</outVariable>
<inVariable localId="13" executionOrderId="0" height="30" width="105" negated="false">
<position x="30" y="823"/>
<connectionPointOut>
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<position x="30" y="854"/>
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<position x="30" y="885"/>
<connectionPointOut>
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<expression>58</expression>
</inVariable>
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<position x="231" y="1103"/>
<inputVariables>
<variable formalParameter="IN1">
<connectionPointIn>
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<connection refLocalId="18">
<position x="231" y="1133"/>
<position x="132" y="1133"/>
</connection>
</connectionPointIn>
</variable>
<variable formalParameter="IN2">
<connectionPointIn>
<relPosition x="0" y="50"/>
<connection refLocalId="22">
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<outputVariables>
<variable formalParameter="OUT">
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<expression>Temperature</expression>
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<expression>ControlDisable</expression>
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<connectionPointIn>
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<expression>Cooler</expression>
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<variable formalParameter="OUT">
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<connectionPointOut>
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</connectionPointOut>
<expression>ControlDisable</expression>
</inVariable>
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<connectionPointIn>
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<connection refLocalId="24" formalParameter="OUT">
<position x="465" y="1264"/>
<position x="411" y="1264"/>
</connection>
</connectionPointIn>
<expression>Heater</expression>
</outVariable>
<inVariable localId="27" executionOrderId="0" height="30" width="146" negated="false">
<position x="36" y="1329"/>
<connectionPointOut>
<relPosition x="146" y="15"/>
</connectionPointOut>
<expression>TemperatureSetPoint</expression>
</inVariable>
<comment localId="28" height="67" width="229">
<position x="343" y="734"/>
<content>
<xhtml:p><![CDATA[Simple sensor simulation]]></xhtml:p>
</content>
</comment>
<comment localId="29" height="67" width="229">
<position x="37" y="978"/>
<content>
<xhtml:p><![CDATA[Climate control]]></xhtml:p>
</content>
</comment>
<comment localId="30" height="464" width="773">
<position x="14" y="16"/>
<content>
<xhtml:p><![CDATA[This examples shows how to work with BACnet extension.
Extensions requires native BACnet stack to be installed nearby Beremiz.
Following directory structure is expected:
<Parent directory>
"beremiz"
"BACnet"
If library is installed elsewhere, then place corresponding paths
in CFLAGS/LDFLAGS in project settings.
For GNU/Linux to install BACnet library in parent directory run following commands:
$ svn checkout https://svn.code.sf.net/p/bacnet/code/trunk/bacnet-stack/ BACnet
$ cd BACnet
$ make
After that BACnet extension is ready to be used in Beremiz projects.
BACnet stack implementation contains a lot of test tools. They could be useful during
debugging and BACnet investigation. See "BACnet/bin/readme.txt" for more information about them.]]></xhtml:p>
</content>
</comment>
</FBD>
</body>
</pou>
<pou name="Simulator" pouType="functionBlock">
<interface>
<outputVars>
<variable name="Out">
<type>
<REAL/>
</type>
</variable>
</outputVars>
<inputVars>
<variable name="MinVal">
<type>
<REAL/>
</type>
</variable>
<variable name="MaxVal">
<type>
<REAL/>
</type>
</variable>
<variable name="PeriodSeconds">
<type>
<INT/>
</type>
</variable>
</inputVars>
<localVars>
<variable name="TON0">
<type>
<derived name="TON"/>
</type>
</variable>
<variable name="seconds">
<type>
<INT/>
</type>
</variable>
<variable name="BaseVal">
<type>
<REAL/>
</type>
</variable>
<variable name="VarVal">
<type>
<REAL/>
</type>
</variable>
</localVars>
</interface>
<body>
<ST>
<xhtml:p><![CDATA[(* pseudo-random variations *)
TON0(IN := TRUE, PT := T#3120s);
IF TON0.Q THEN
TON0(IN := FALSE);
END_IF;
seconds := TIME_TO_INT(TON0.ET);
BaseVal := (MaxVal + MinVal)/2.0;
VarVal := (MaxVal-MinVal)*INT_TO_REAL((seconds MOD PeriodSeconds) - (PeriodSeconds/2))/INT_TO_REAL(PeriodSeconds);
Out := BaseVal + VarVal;]]></xhtml:p>
</ST>
</body>
</pou>
</pous>
</types>
<instances>
<configurations>
<configuration name="config">
<resource name="resource1">
<task name="task0" priority="0" interval="T#20ms">
<pouInstance name="instance0" typeName="program0"/>
</task>
</resource>
</configuration>
</configurations>
</instances>
</project>