[Python] Cannot write data to ECAT IO slaves using...

I'm experimenting with pyads library and have an application where I need to read and write data from ECAt IO slaves (DI, DO, AI, AO). I have one ECAT slave EL3174-0002 4Ch. Ana. Input, where all variables of all four channels are type INT. Using read_list_by_name works without any problem, but trying to write using write_list_by_name returns ADS error 1793 "Service is not supported by server". On the other hand, writing one by one works - but the performance is bad.

This is a code snippet that show this:

if __name__ == "__main__":
ECAT_IO_ADDRESS = "10.238.65.188.2.1"
ECAT_IO_PORT = 27905

var_list = [
"Term 5 (EL3174-0002).AI Standard Channel 1.Value",
"Term 5 (EL3174-0002).AI Standard Channel 2.Value",
]

# Create dictionary from list to be used in write_to list
data_to_write = {name: random.randint(0, 1024) for name in var_list}

with pyads.Connection(PLC_AMS_NET_ID, ECAT_IO_PORT) as ecat:
data_read = ecat.read_list_by_name(var_list)
print("Data read from ECAT AI: ", data_read)
print("Data prepared to write to ECAT AI: ", data_to_write)
ret_write = ecat.write_list_by_name(data_to_write)

#for name, value in data_to_write.items():
#ecat.write_by_name(name, value)


This code will produce the following error:

in adsSyncReadWriteReqEx2
raise ADSError(err_code)
pyads.pyads_ex.ADSError: ADSError: Service is not supported by server (1793).


If I comment that line and uncomment the for-loop, all values are written correctly. I would like to know if this is a bug in the pyads implementation, or the ADS server cannot really support writing data in chunks.

Thanks in advance.

I tried to use pyads.connection.Connection.write_list_by_name exactly as stated in the documentation and using the same format that is returned by read_list_by_name.

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