4 Replies Latest reply on Sep 21, 2018 1:30 PM by Dan Fishman

    Totalizer vs. PI AF

    PernilleSilberg

      Hi There,

      We want to replace our current totalizer tags with PI AF - if this is possible..

      I have the challenge that i want to calculate an average of a tag/or attribute over a given period, lets say 30 min, but i want the timestamp to be set to the start of the period.

      Using totalizer this is a no brainer - but i would rather avoid totalizers as we somtimes have delay in data and therefore we sometimes get wrong calculated totalizers.

       

      What i so far have tried is to use PI AF (we are using version 2017 R2) - but we get no data into our database.

      my expression is Tagavg('attribute','*-30m','*'), periodic triggered every 30 min and with the "output time stamp" set to relative to triggertime: *-30m. Here i'm thinking that i want the timestamp for the avg to be in the start of the period and not in the end... Am i thinking wrong ?

      The system gives me in the preview results a nice table and trend - that shows me the data i want - and I can create the tags - but no data is written to the tag. The tag just is freezed at pt created.

      Please assist

      Cheers Pernille

        • Re: Totalizer vs. PI AF
          KenjiHashimoto

          For the error, you should check message logs on Analysis service machine. It might be no writing access. Is there a pi tag settings for output attribute?

          The configuration seems no problem. For troubleshooting, it is good to check with easy syntax with simple settings. (If there is an existing tag that write values from the analysis service, then it is this one specific analysis issue though) Can you see green icon when you run it?

           

          By the way, you mention that there is a delay of the data. So in that case, you can use syntax like TagAvg('attribute','*-40m','*-10m') with output time *-40m.

          It allows analysis for 10 minutes delay for the input tags.

          4 of 4 people found this helpful
          • Re: Totalizer vs. PI AF
            sraposo

            One more thing to add to Kenji's reply, if you have a PI Collective, it's possible that the PI Analysis Service isn't going through the PI Buffer Subsystem and therefore the data is not being fanned to all members. PSE could be connected to one member while the data is only updating on the other member.

             

            Thanks,
            Seb

            2 of 2 people found this helpful
            • Re: Totalizer vs. PI AF
              PernilleSilberg

              Thanks Guys,

              I managed to get trough - it was the writing "rights" to the tag that was the issue.

              Will have to look more into this.

              Cheers Pernille

              1 of 1 people found this helpful