Problem with copco MKIV gateway using rs 485 to rs 232 communication


Thread Starter


Hello everyone

I have a problem with a atlas copco MKIV gateway which is CAN to rs485 wired to rs232 converter to a pc.

My pc is good checked by loopback. Checked thoroughly with user manuals of device. I tried all sorts and combination of termination. I always get illegal response. In Modscan i see the response is 255 23 233 222 179 221 that's all i see always.

ATLASCOPCO Elektronikon MkIV, 1900 0711 41 first device, MOXA TCC-100I rs485 to 232 converter and finally a laptop. I didn't get a valid response and my converter led are all lit ok. I have used simplymodbus, windmill, commonitors softwares but no valid response.

Please share.

Thanks in advance
Your response in Hex Format is:

ff 17 e9 de b3 dd

That data stream does not pass a CRC16 check and it does not appear to be a valid Modbus Error response (where 0x80 is added to the requested function code).

It might help decipher the problem if you provided the host request.
I've heard that JBus is a minor derivative of Modbus, but I had never heard that the CAN protocol has any resemblance to Modbus.

Are you sure the device's protocol is CAN?

I don't know what Windmill is, but SimplyModbus talks Modbus, not CAN.

You cannot expect that a Modbus master will talk to/with a CAN bus device.
The manual says:

"Before the module can be used for a modbus connection the appropriate software must be loaded. This can be done by AC Service personal with the AC Field Downloading Program (FDP)."

Did you know?