How to establish MPI-connection with python-libnodave?

[mattbue]

Hi, i need to know how to establish a MPI-connection (USB-MPI-Adapter) to my PLC in python. Can someone provice me some demo code?

In the web i can only find how to establish TCP-connections.

Thanks

[keremcelenn]

Hello, did you solve the communication between mpi and python-plc? Can you help me?

[mathias-ch1903]

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!