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Dataitem, multiplier and additive


  • hi, i have some data items from a modbus source with unusual modifiers...

    12bit analogue, with 820 - 4095 = 0 - 100 %

    so i use * (0.0303) and + (-24)

    this works A ok for all read only sources...

    however, i now have some write data... and by rights, it should reverse the process to produce the scaled value to the register..

    but when i enter, for example 50... i get 27 come back from the modbus source...

    and entering 80 gives me 57...

    i have other tags with simple 0.1 multipliers, so it seems the additive must be the problem.

    it looks like, in the case of writing the data back, its ignoring the additive....

    i.e.

    50 should be 50+24 = 74, 74 / 0.0303 = 2442 ( 49.99 - correct)

    whereas, i'm seeing 50 (not +24) = 50, 50 / 0.0303 = 1650 (25.99 - incorrect).

    can this be fixed please?


  • The reverse arithmetic was present, but the operations were in the reverse order. Incoming: value = input * mult + add. But, output = value / mult - add. The operation has been corrected to be output = (value - add) / mult. This will be available in the next release.


  • thanks....

    look forward to that release