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BRX Do-More PLCs and 'Global' tags

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  • BRX Do-More PLCs and 'Global' tags


    I'm working on a system that splits control of a large machine between two BRX PLCs (one on each side). Both are connected to an Ethernet LAN and thereby to an EA9 C-More panel. The machine is mean to execute sequencing recipes selected at the panel.

    I want to have ONE recipe file for the system and ONE codebase for the two PLCs. The PLCs identify which side they are on via looking at what they are attached to, and know which I/O they are to control.

    Because I want to have a single recipe file, and single codebase, I need to be able to have a recipe file loaded into tag names that are duplicated between the RHS PLC and the LHS PLC. Essentially 'global' tags.

    Is it possible to accomplish this with the C-More and BRX's with the C-More communicating with both PLCs at the same time? Perhaps have it load the recipe into a 'supervisor' PLC which then pushes to the other? Some other way that is not apparent to me (sort of a newbie)?



  • #2
    The C-more can talk to both PLCs, but I think recipe items would have to be duplicated so the tagnames point to the 2 different PLCs. The Do-more RX and WX instructions allow easy copying between PLCs, even the same address in both PLCs is no problem. I have done one system that the HMIs write to both as needed, but the PLC that needs to know what the other is doing has a WX and RX handling that. The PLCs are not duplicates as you need, just one has to be standalone if needed and the other (that has the WX and RX) has to know the standalone is doing its thing.

    There is also Peerlink, but I am not as enamored with it because it has a separate setup required.


    • #3
      Originally posted by Mike Nash View Post
      There is also Peerlink, but I am not as enamored with it because it has a separate setup required.
      What do you mean by separate setup?


      • #4
        Originally posted by BobO View Post

        What do you mean by separate setup?
        You got me there! I was mixing memories apparently. I have used Peer to Peer on a D2-260 with ECOM100 and Modbus TCP and ERM and EBC and it gets confusing. I had done the logic to try to configure a new ECOM100 automatically in the D2-260, but it still required using NetEdit to configure the Peer to Peer. If the comments get lost for the code, then the note about how to do it gets lost too. And since the D2-260 doesn't store the annotation... uploads happen. Do-more does store the annotation though, so that's cool.

        I looked at PEERLINK vs WX, RX on a recent job and the PEERLINK just feels more difficult to use. I especially find I am loathe to going back to "junk drawer" memory tables where it's up to me to keep track of which locations go together and what type of data it's supposed to be.


        • #5
          Wasn't trying to 'get you', but I suspected that to be the case.

          PEERLINK was designed for ease of use. It's for the guy who just needs to share a few tags between 2 or more PLCs...without becoming an 'expert'.

          RX/WX is for guys like you.