Hi there,
I am trying to run a Carel PCOXs based system using a RS485 serial card to talk modbus (9600 @ 8N1) to an Altivar 61 VFD. The VFD is programmed to "listen" at the right baud and parity but I get nothing but CRC errors on the VFD. When I hook it up to my laptop using Modbus Tester, every message polled gets a valid response. I've checked the wiring and it's fine (in fact when I hook up my laptop, I hook it up through the terminals on the PLC with the PLC off).
It's not the drive since I can start it on the laptop.
Any ideas? I tried to simulate the CRC errors and the only time I can duplicate it is if I connect the + and - together. Then I get the same pattern of CRC errors. Could the program be doing this???
Thanks.
K
I am trying to run a Carel PCOXs based system using a RS485 serial card to talk modbus (9600 @ 8N1) to an Altivar 61 VFD. The VFD is programmed to "listen" at the right baud and parity but I get nothing but CRC errors on the VFD. When I hook it up to my laptop using Modbus Tester, every message polled gets a valid response. I've checked the wiring and it's fine (in fact when I hook up my laptop, I hook it up through the terminals on the PLC with the PLC off).
It's not the drive since I can start it on the laptop.
Any ideas? I tried to simulate the CRC errors and the only time I can duplicate it is if I connect the + and - together. Then I get the same pattern of CRC errors. Could the program be doing this???
Thanks.
K