How to establish MPI-connection with python-libnodave? #1

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1. keremcelenn commented on May 20, 2021

   

   keremcelenn

   on May 20, 2021

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   Hello, did you solve the communication between mpi and python-plc? Can you help me?
2. mathias-ch1903 commented on Oct 30, 2021

   

   mathias-ch1903

   on Oct 30, 2021

   Last edited by mathias-ch1903

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   Hi
   After long debugging sessions and tests direct with the libnodave I found the following working (only with Python 3, python 2.7 is always seg-faulting) solution:

   -- snipp --
   import libnodave

   link = libnodave.libnodave()

   def main():

   localMPI = 0
   plcMPI = 2 #anpassen, je nach CPU Adresse
   plcRack = 0
   plcSlot = 0
   
   #link.SetDebug(99)
   print('01')
   link.set_port(b'/dev/ttyUSB0', b'38400', b'o')
   
   print('02')       
   link.new_interface(b'IF1', localMPI, libnodave.daveProtoMPI2, libnodave.daveSpeed187k)
   
   print('03')
   link.set_timeout(5000000)
   
   print('04')
   link.init_adapter()   
   
   print('05')
   link.connect_plc(plcMPI, plcRack, plcSlot)   
   
   print('06')   
   print('M200.0 Immer EIN', link.get_marker(200,0))   
   link.disconnect()
   

   if name == 'main':
   main()
   -- snapp --

   Adapter is a Siemens RS232/MPI Adapter (via FTDI USB/RS232) connected to a S7-315DP CPU
   You have to convert the python-libnodave to python3 by using "2to3" and apply the change:
   self.buffer = ctypes.create_string_buffer(b'buffer')

   self.buffer = ctypes.create_string_buffer('buffer')

   Hopt it helps!

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