1 Reply Latest reply on Oct 6, 2016 6:45 PM by Dan Fishman

    PrevVal and PrevEvent values in ACE

    Babar

      Hi,

      The requirement of my calculation is to find the previous value of a PI tag however, with the prevVal function, I am still getting the latest value. For the input tag, step is ON and I do not want to change the tag configuration.  What would be the simplest way to get the correct previous value?

       

      Thanks,

      Babar

        • Re: PrevVal and PrevEvent values in ACE
          Dan Fishman

          I wonder if this is due to clock drift.  You might want to try setting in your ACE code:

          PIACEBIFunctions.AdjustClockDrift = False

           

          Also, if you want the last snapshot, and not the last archived value, you should use a module-level variable that is initially set to the current snapshot value.  After you do you calculation, you then set the current snapshot value to this variable, such that the next calculation has access to this value.