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  • Need advice on PLC selection

    Ok guys, help me out....

    I am putting together a demo for a SCADA system and I need a PLC that can take a discrete input and write it to a bit in a 16 bit word. I need to be able to assign these bits to specific points in a specific MODBUS register.

    Say I need x1 status to write to Bit 0 in register 2014 and x2 to write to Bit 1 in the same register. so if both were on it would read 0011.

    Which of the AD PLC's can handle this? Are there any examples of how to program this?

    Thanks for the help!


  • #2
    any.
    how easy do you require?

    in no order

    do-more can
    pxk can
    click can
    Last edited by kewakl; 02-12-2018, 07:38 PM.

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    • #3
      click may be the quick/dirty easiest. no modbus security as in domore
      Code:
      . ' copy x1,x2 to c so you can expand if you need
      .         x1                     c1
      .----------] [--------------------(o)
      .
      .         x2                     c2
      .----------] [--------------------(o)
      .
      . ' you could replace C1 and C2 in the copy with X1 and X2
      . ' but, I will assume that you may need to expand.
      . ' of course you could just edit the copy instruction
      . ' but that would not allow you to pick order/range/gaps...
      .                                 |
      .---------------------------------+ copy pack
      .                                 | C1   C16
      .                                 | DH1
      .                                 +---------
      .
      . 'copy result to DS2014 (mb reg 2014                              
      . 'may need to copy to DS2013 for some scada implementations
      .                                 |
      .---------------------------------+ copy single
      .                                 | DH1
      .                                 | DS2014
      .                                 +---------
      .
      Last edited by kewakl; 02-12-2018, 07:31 PM.

      Comment



      • #4
        pxk will require that you assign a modbus address to a register. no issue. do that in the tag database
        there are several way you can accomplish this - depending on sw ver (bit-of-word support)
        Code:
        .                                 |
        .---------------------------------+pkb
        .                                 |  input          output
        .                                 |  di-0.1.1.1     reg_2014
        .                                 |  di-0.1.1.2
        .                                 |  0
        .                                 |  0
        .                                 |  0
        .                                 |  0
        .                                 |continue to bit 32 
        Code:
        .   di-0.1.1.1                  reg_2014:1
        .-------] [--------------------------(o)
        .                                 
        .   di-0.1.1.2                  reg_2014:2
        .-------] [--------------------------(o)
        .                                 
        .                                 

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        • #5
          I assume that domore will be something like this
          Code:
          .
          .   st1                             |
          .---] [-----------------------------+ move
          .                                   |   x1
          .                                   |   mhr2014:0
          .                                   +----------------
          .
          .   st1                             |
          .---] [-----------------------------+ move
          .                                   |   x2
          .                                   |   mhr2014:1
          .                                   +----------------
          .
          someone more fluent in domore/domore modbus will probably offer advice, or indicate where this sample fails.
          I assume that mhr will be 'public' to external devices. I do not know if you need move to/from mhr to the normal domore v/d/n address registers if needed for anything else.
          Last edited by kewakl; 02-12-2018, 07:44 PM.

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          • #6
            Do-more is simple.

            Code:
            .
            .    X1                              MHR2014:0
            .---]  [-------------------------------( OUT )
            .
            .    X2                              MHR2014:1
            .---]  [-------------------------------( OUT )
            . 

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            • #7
              Bob you could actually...um...Do-More!!
              Attached Files

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              • #8
                Originally posted by BobO View Post
                Do-more is simple.

                Code:
                .
                . X1 MHR2014:0
                .---] [-------------------------------( OUT )
                .
                . X2 MHR2014:1
                .---] [-------------------------------( OUT )
                .
                so i wasn't completely off-base there.
                i had that format in the pxk, should have checked that format in dmd


                @forum: quit munging the [ c o d e ] ... [ / c o d e ]

                Comment



                • #9
                  In PxK you can also use the PKB instruction and put bits wherever you wish to in the word.

                  Click image for larger version

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                  Attached Files

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                  • #10
                    Wow guys, thanks a ton. I am new to the MODBUS side of programming the AD PLC range. I may come back with more questions.

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