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Python service with PISDK

Question asked by Dariva on Oct 2, 2019
Latest reply on Nov 18, 2019 by Dariva

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I wrote a Python Script to extract some data from a PI server using the PISDK and the Dispatch module from win32com.client.dynamic library. It works perfectly but when I put this script to run as a windows services I am getting an error using the PIPoints method. The error message I receive is this one.

(-2147352567, 'Exception occurred.', (0, 'PISDK', None, 'pisdk.chm', 0, -2147467262), None)

To put the application to work I created a scheduled task in window to run the script. This is working fine.

Does any one have experience with this kind of implementation?

Regards,

Dariva Oct 4, 2019 5:29 PM

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I manage to solve the problem by using the PIconnect python module. You can find more about it in the link below.

PIconnect documentation — PIconnect 0.7.1 documentation

The only detail is that you need to start the service with a user allowed to access the PI servers. If you start the service with Local System it gives a error.

Regards,

Leandro

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9 Replies

Steve Boyko Oct 2, 2019 6:12 PM
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What user is the Windows service set to run as? It sounds like a permissions error. The service would run as a different user than the logged in user running it interactively.
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Dariva Oct 2, 2019 6:23 PM
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Hi Steve,
This came to my mind. I tried to start the service with my login which has access to the PI Server, but it give the same error. Originally I started it with the local system account.
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- Steve Boyko @ Dariva on Oct 2, 2019 6:27 PM
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  OK. Maybe it's a difference in the interactive versus service environment? Error -2147467262 is 0x80004002 in hex, which I believe is "no such interface". Maybe the Python can't find PI SDK when run as a service? Maybe explicitly set PATH or environment variables or something like that?
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  - Dariva @ Steve Boyko on Oct 2, 2019 6:32 PM
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    Ok. I will check this. Thanks for the tip!
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Dariva Oct 4, 2019 5:29 PM
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I manage to solve the problem by using the PIconnect python module. You can find more about it in the link below.

PIconnect documentation — PIconnect 0.7.1 documentation

The only detail is that you need to start the service with a user allowed to access the PI servers. If you start the service with Local System it gives a error.

Regards,
Leandro
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- James Devine @ Dariva on Nov 7, 2019 4:25 PM
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  Olá Leandro!
  
  How do I install the PIconnect 0.7.1 module? I have tried following the online documentation, but after I run the 'python setup.py install' and run a simple script to connect to the pi server and print out its name I get this error message:
  Traceback (most recent call last):
  File "c:\Users\vdevine\.vscode\extensions\ms-python.python-2019.10.44104\pythonFiles\ptvsd_launcher.py", line 43, in <module>
  main(ptvsdArgs)
  File "c:\Users\vdevine\.vscode\extensions\ms-python.python-2019.10.44104\pythonFiles\lib\python\old_ptvsd\ptvsd\__main__.py", line 432, in main
  run()
  File "c:\Users\vdevine\.vscode\extensions\ms-python.python-2019.10.44104\pythonFiles\lib\python\old_ptvsd\ptvsd\__main__.py", line 316, in run_file
  runpy.run_path(target, run_name='__main__')
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\runpy.py", line 263, in run_path
  pkg_name=pkg_name, script_name=fname)
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\runpy.py", line 96, in _run_module_code
  mod_name, mod_spec, pkg_name, script_name)
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\runpy.py", line 85, in _run_code
  exec(code, run_globals)
  File "c:\Users\vdevine\Desktop\START.2019\PI.Software\PI.Connect\PIconnect-0.7.1\tests\connect_to_pi_server.00.py", line 1, in <module>
  import PIconnect as PI
  ModuleNotFoundError: No module named 'PIconnect'
  
  What am I missing here??
  BTW the script is:
  # Connect to the default pi server and print its name =>
  import PIconnect as PI
  with PI.PIServer() as server:
  print(server.server_name)
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  - Dariva @ James Devine on Nov 7, 2019 10:38 PM
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    Hi James,
    
    I am not with my laptop as I am on vacation but the problem is that your system is not recognizing the new module. Restarting your computer usually solve this. Hope this help.
    
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- gleon @ Dariva on Nov 18, 2019 12:47 PM
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  Leandro,
  
  Were you able to get your data using PIconnect library?
  When I tried, I just got "Testing" server available.
  Do I need to do something before ?
  Can you write an example code?
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  - Dariva @ gleon on Nov 18, 2019 2:14 PM
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    Hi Gabriela,
    
    Yes. I am able to get data using the PIconnect library. At least here in my system I just need to install the PIconnect as we install any other python module.
    
    I think that your problem is access permition to the PI server.
    Are you able to connect to the server using ProcessBook?
    If you can maybe there is some network issue in your system. Checking the firewall is a good idea. Here they are the source of 99% of connections issues.
    
    Hope this help
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Python service with PISDK

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