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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="http://www.plcopen.org/xml/tc6_0201" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xhtml="http://www.w3.org/1999/xhtml" xsi:schemaLocation="http://www.plcopen.org/xml/tc6_0201">

<fileHeader companyName="Unknown" productName="Generic PLC" productVersion="1" creationDateTime="2013-01-29T14:01:00" contentDescription="This example shows logging functionality in Beremiz.
Here are shown two ways of logging:
- from IEC PLC program;
- from python extension.
"/>

<contentHeader name="Logging example" modificationDateTime="2018-08-24T13:12:45">

<coordinateInfo>

<fbd>

<scaling x="0" y="0"/>

</fbd>

<ld>

<scaling x="0" y="0"/>

</ld>

<sfc>

<scaling x="0" y="0"/>

</sfc>

</coordinateInfo>

</contentHeader>

<types>

<dataTypes/>

<pous>

<pou name="program0" pouType="program">

<interface>

<localVars>

<variable name="beat">

<type>

<BOOL/>

</type>

</variable>

<variable name="count">

<type>

<INT/>

</type>

</variable>

<variable name="LOGGER0">

<type>

<derived name="LOGGER"/>

</type>

</variable>

<variable name="lvl">

<type>

<derived name="LOGLEVEL"/>

</type>

<initialValue>

<simpleValue value="INFO"/>

</initialValue>

</variable>

<variable name="Timer">

<type>

<derived name="TOF"/>

</type>

</variable>

</localVars>

</interface>

<body>

<FBD>

<inVariable localId="2" height="30" width="170" executionOrderId="0" negated="false">

<position x="507" y="365"/>

<connectionPointOut>

<relPosition x="170" y="15"/>

</connectionPointOut>

<expression>'IEC side logging: beat #'</expression>

</inVariable>

<block localId="3" width="59" height="40" typeName="NOT" executionOrderId="0">

<position x="241" y="287"/>

<inputVariables>

<variable formalParameter="IN">

<connectionPointIn>

<relPosition x="0" y="30"/>

<connection refLocalId="14" formalParameter="Q">

<position x="241" y="317"/>

<position x="197" y="317"/>

</connection>

</connectionPointIn>

</variable>

</inputVariables>

<inOutVariables/>

<outputVariables>

<variable formalParameter="OUT">

<connectionPointOut>

<relPosition x="59" y="30"/>

</connectionPointOut>

</variable>

</outputVariables>

</block>

<inOutVariable localId="4" height="30" width="51" executionOrderId="0" negatedOut="false" negatedIn="false">

<position x="66" y="304"/>

<connectionPointIn>

<relPosition x="0" y="15"/>

<connection refLocalId="3" formalParameter="OUT">

<position x="66" y="319"/>

<position x="37" y="319"/>

<position x="37" y="390"/>

<position x="314" y="390"/>

<position x="314" y="317"/>

<position x="300" y="317"/>

</connection>

</connectionPointIn>

<connectionPointOut>

<relPosition x="51" y="15"/>

</connectionPointOut>

<expression>beat</expression>

</inOutVariable>

<block localId="5" width="68" height="98" typeName="ADD" executionOrderId="0">

<position x="463" y="403"/>

<inputVariables>

<variable formalParameter="IN1">

<connectionPointIn>

<relPosition x="0" y="39"/>

<connection refLocalId="10" formalParameter="OUT">

<position x="463" y="442"/>

<position x="452" y="442"/>

<position x="452" y="442"/>

<position x="455" y="442"/>

<position x="455" y="442"/>

<position x="445" y="442"/>

</connection>

</connectionPointIn>

</variable>

<variable formalParameter="IN2">

<connectionPointIn>

<relPosition x="0" y="78"/>

<connection refLocalId="6">

<position x="463" y="481"/>

<position x="453" y="481"/>

<position x="453" y="482"/>

<position x="454" y="482"/>

<position x="454" y="483"/>

<position x="444" y="483"/>

</connection>

</connectionPointIn>

</variable>

</inputVariables>

<inOutVariables/>

<outputVariables>

<variable formalParameter="OUT">

<connectionPointOut>

<relPosition x="68" y="39"/>

</connectionPointOut>

</variable>

</outputVariables>

</block>

<inOutVariable localId="6" height="30" width="103" executionOrderId="0" negatedOut="false" negatedIn="false">

<position x="341" y="468"/>

<connectionPointIn>

<relPosition x="0" y="15"/>

<connection refLocalId="5" formalParameter="OUT">

<position x="341" y="483"/>

<position x="320" y="483"/>

<position x="320" y="518"/>

<position x="544" y="518"/>

<position x="544" y="442"/>

<position x="531" y="442"/>

</connection>

</connectionPointIn>

<connectionPointOut>

<relPosition x="103" y="15"/>

</connectionPointOut>

<expression>count</expression>

</inOutVariable>

<block localId="8" width="67" height="144" typeName="CONCAT" executionOrderId="0">

<position x="727" y="329"/>

<inputVariables>

<variable formalParameter="IN1">

<connectionPointIn>

<relPosition x="0" y="51"/>

<connection refLocalId="2">

<position x="727" y="380"/>

<position x="677" y="380"/>

</connection>

</connectionPointIn>

</variable>

<variable formalParameter="IN2">

<connectionPointIn>

<relPosition x="0" y="113"/>

<connection refLocalId="9" formalParameter="OUT">

<position x="727" y="442"/>

<position x="680" y="442"/>

</connection>

</connectionPointIn>

</variable>

</inputVariables>

<inOutVariables/>

<outputVariables>

<variable formalParameter="OUT">

<connectionPointOut>

<relPosition x="67" y="51"/>

</connectionPointOut>

</variable>

</outputVariables>

</block>

<block localId="9" width="119" height="40" typeName="INT_TO_STRING" executionOrderId="0">

<position x="561" y="412"/>

<inputVariables>

<variable formalParameter="IN">

<connectionPointIn>

<relPosition x="0" y="30"/>

<connection refLocalId="5" formalParameter="OUT">

<position x="561" y="442"/>

<position x="531" y="442"/>

</connection>

</connectionPointIn>

</variable>

</inputVariables>

<inOutVariables/>

<outputVariables>

<variable formalParameter="OUT">

<connectionPointOut>

<relPosition x="119" y="30"/>

</connectionPointOut>

</variable>

</outputVariables>

</block>

<block localId="10" width="106" height="40" typeName="BOOL_TO_INT" executionOrderId="0">

<position x="339" y="412"/>

<inputVariables>

<variable formalParameter="IN" edge="rising">

<connectionPointIn>

<relPosition x="0" y="30"/>

<connection refLocalId="3" formalParameter="OUT">

<position x="339" y="442"/>

<position x="314" y="442"/>

<position x="314" y="317"/>

<position x="300" y="317"/>

</connection>

</connectionPointIn>

</variable>

</inputVariables>

<inOutVariables/>

<outputVariables>

<variable formalParameter="OUT">

<connectionPointOut>

<relPosition x="106" y="30"/>

</connectionPointOut>

</variable>

</outputVariables>

</block>

<block localId="11" width="65" height="209" typeName="LOGGER" instanceName="LOGGER0" executionOrderId="0">

<position x="907" y="266"/>

<inputVariables>

<variable formalParameter="TRIG">

<connectionPointIn>

<relPosition x="0" y="51"/>

<connection refLocalId="3" formalParameter="OUT">

<position x="907" y="317"/>

<position x="300" y="317"/>

</connection>

</connectionPointIn>

</variable>

<variable formalParameter="MSG">

<connectionPointIn>

<relPosition x="0" y="114"/>

<connection refLocalId="8" formalParameter="OUT">

<position x="907" y="380"/>

<position x="794" y="380"/>

</connection>

</connectionPointIn>

</variable>

<variable formalParameter="LEVEL">

<connectionPointIn>

<relPosition x="0" y="177"/>

<connection refLocalId="12">

<position x="907" y="443"/>

<position x="893" y="443"/>

<position x="893" y="445"/>

<position x="879" y="445"/>

</connection>

</connectionPointIn>

</variable>

</inputVariables>

<inOutVariables/>

<outputVariables/>

</block>

<inVariable localId="12" height="30" width="79" executionOrderId="0" negated="false">

<position x="800" y="430"/>

<connectionPointOut>

<relPosition x="79" y="15"/>

</connectionPointOut>

<expression>lvl</expression>

</inVariable>

<block localId="14" typeName="TOF" instanceName="Timer" executionOrderId="0" height="98" width="47">

<position x="150" y="278"/>

<inputVariables>

<variable formalParameter="IN">

<connectionPointIn>

<relPosition x="0" y="39"/>

<connection refLocalId="4">

<position x="150" y="317"/>

<position x="133" y="317"/>

<position x="133" y="319"/>

<position x="117" y="319"/>

</connection>

</connectionPointIn>

</variable>

<variable formalParameter="PT">

<connectionPointIn>

<relPosition x="0" y="78"/>

<connection refLocalId="1">

<position x="150" y="356"/>

<position x="133" y="356"/>

<position x="133" y="359"/>

<position x="117" y="359"/>

</connection>

</connectionPointIn>

</variable>

</inputVariables>

<inOutVariables/>

<outputVariables>

<variable formalParameter="Q">

<connectionPointOut>

<relPosition x="47" y="39"/>

</connectionPointOut>

</variable>

<variable formalParameter="ET">

<connectionPointOut>

<relPosition x="47" y="78"/>

</connectionPointOut>

</variable>

</outputVariables>

</block>

<inVariable localId="1" executionOrderId="0" height="30" width="52" negated="false">

<position x="65" y="344"/>

<connectionPointOut>

<relPosition x="52" y="15"/>

</connectionPointOut>

<expression>T#3s</expression>

</inVariable>

<comment localId="15" height="238" width="675">

<position x="27" y="16"/>

<content>

<xhtml:p><![CDATA[This example shows logging functionality in Beremiz.

Here are shown two ways of logging:

- from IEC PLC program;

- from python extension.

In IEC PLC program every third second (beat) new message is generated and put in PLC log.

See function blocks below.

Every 15 seconds status of PLC program is put in PLC log from python extension.

For more information about logging from python look at 0.x: py_ext_0 implementation in project tree.

]]></xhtml:p>

</content>

</comment>

</FBD>

</body>

</pou>

</pous>

</types>

<instances>

<configurations>

<configuration name="config">

<resource name="resource1">

<task name="task0" priority="0" interval="T#100ms">

<pouInstance name="prg" typeName="program0"/>

</task>

</resource>

</configuration>

</configurations>

</instances>

</project>