Communication between Controllers

  • Hopefully quick question here. I'm working on my first multiple robot application and i want to build in some cross controller communication via Ethernet to keep their movements in sync with each other. I haven't found a good way to do that. Anyone have a good solution for this? It doesn't need to be very robust, I was planning on just sending move completions back and forth. Both controllers are also linked to a PLC that is controlling them both. I could use the PLC to snyc them, but I would rather have it bypass the plc as a secondary system.

    Update: I found the IO Cell Linker tool and have successfully 'linked' the digital out and the digital input. However when the program runs, the input status is a "?" as if it isn't reading the value. I tried doing a dioGet and just using the digital output ex: wait(do_link==true) but the "?" never goes away.... I tried a full power down to see if the IO needed to update but haven't been able to figure out this issue.

    Thanks in advance!

  • AD
  • Hello snyffeler,

    the IO Cell Linker is a tool which can be used to link two or more emulated controllers to test their communication. This does not apply to real controllers. It basically is a simulation of the real wiring.

    If you want to communicate between two real controllers, you need a fieldbus or socket communication. The easiest would be a TCP-IP socket communication. One controller would be server and the other client.

    The difference between theory and practice is greater in practice than in theory.

  • Thanks Psyril,

    Yeah what I've discovered is to setup another fieldbus would require more hardware since I'm already using EIP to communicate with a PLC but that works as a master/slave (adapter/scanner).

    Do you know if it is possible to setup TCP-IP communication purely software?

  • What do you mean? You need at least a connection (RJ45 cable on J204 or J205) between the two controllers. It's also ok if they are simply in the same network. The rest is purely software.

    The difference between theory and practice is greater in practice than in theory.

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