Dear All,
I hope someone can assist me with a dispatch problem that I am facing.
Let me briefly explain my case. I am implementing a monitoring and
reporting application for one of our manufacturing machines. I use the
COM interface provided by the PLC manufacturer (Siemens). Since it is
a long running program and the PythonWin GUI becomes sort of
unresponsive I would like to run the data extraction operation through
a normal Python shell (DOS/PowerShell terminal). The problem that I
face is that I cannot dispatch the automation object through the
normal Python shell (see traceback below). It works fine in the
interactive PythonWin console (see at the bottom of the post). I would
be very gratefull if someone can provide me with some hints on how to
solve this problem. Maybe somebody knows the difference in running an
interactive console or a normal Python shell?
I have been struggling with the issue for a few days now. It is
becoming quite urgent now, because we are required to log the
manufacturing data on a higher rate than we do now. We have a tool
implemented in VB, but is is completely hardcoded to only run at a one
minute time interval. We would like to be more flexible, but use
Python to do so.
Thanks in advance,
Marco
Python 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
>>> from win32com.client import Dispatch
>>> server = Dispatch('OPC.Automation.1')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "c:\python27\lib\site-packages\win32com\client\__init__.py", line 95, in
Dispatch
dispatch, userName = dynamic._GetGoodDispatchAndUserName(dispatch,userName,c
lsctx)
File "c:\python27\lib\site-packages\win32com\client\dynamic.py", line 108, in
_GetGoodDispatchAndUserName
return (_GetGoodDispatch(IDispatch, clsctx), userName)
File "c:\python27\lib\site-packages\win32com\client\dynamic.py", line 85, in _
GetGoodDispatch
IDispatch = pythoncom.CoCreateInstance(IDispatch, None, clsctx, pythoncom.II
D_IDispatch)
pywintypes.com_error: (-2147023898, 'Invalid access to memory location.', None,
None)
PythonWin 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit
(Intel)] on win32.
Portions Copyright 1994-2008 Mark Hammond - see 'Help/About PythonWin'
for further copyright
information.
>>> from win32com.client import Dispatch
>>> server = Dispatch('OPC.Automation.1')
>>> print server
<win32com.gen_py.OPC DA Automation Wrapper 2.02.IOPCGroups instance at
0x16331400>
>>>
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