Runtime/PLCObject : move call to PreStartPLC right after call to the "start" method of all python extensions, and then just before the start of the python loop executing python_* blocks.
<?xml version='1.0' encoding='utf-8'?>
<PyFile xmlns:xhtml="http://www.w3.org/1999/xhtml" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<variables>
<variable name="SomeVarName" type="DINT" onchange="MyFunc"/>
<variable name="Grumpf" type="STRING" initial="'mhoo'" onchange="MyFunc"/>
</variables>
<globals>
<xhtml:p><![CDATA[
print "All python PLC globals variables :", PLCGlobalsDesc
print "Current extention name :", __ext_name__
def MyFunc(*args):
print args
]]></xhtml:p>
</globals>
<init>
<xhtml:p><![CDATA[
]]></xhtml:p>
</init>
<cleanup>
<xhtml:p><![CDATA[
]]></xhtml:p>
</cleanup>
<start>
<xhtml:p><![CDATA[
]]></xhtml:p>
</start>
<stop>
<xhtml:p><![CDATA[
]]></xhtml:p>
</stop>
</PyFile>