Connecting to a PLC from a PC through CAN/CANopen

Question

First I have to say that I am not very experienced with neither Linux nor CAN/CANopen, so if something here is unclear or missing anything critical, please tell me.

I have a project where I require to connect a PC to a PLC via CAN/CANopen. I have a CAN-USB converter (canusb.com) and a PLC by Festo.

I have compiled the CANopen stack (CanFestival), but where do I go from here? It looks extremely complicated, and I really don’t understand it at all.

(My first goal would be to establish contact with the PLC through the CAN adapter and verify in some way that they are able to talk. The main goal is to be able to turn some valves on and off on the PLC by setting some registers.)

Answer 1

I'm familiar with CANopen, having written a stack and designed devices for it. In my opinion, this is going to be a major learning curve for you and will most likely take weeks of work. Most PLCs support most, if not all, fieldbus protocols. Does yours support Modbus? If it does, then you'll be up and running in a day or two: Modbus is simple to program.

I was in the same situation as you last year, and keeping in mind my deep understanding of CANopen, that's how I handled it. That said, I don't work by the hour, and it was a fixed price job, so I was after the overall cheapest solution, and this required buying a PLC module that supported Modbus.