6 Replies Latest reply on Apr 23, 2010 5:32 AM by formerpigeek

    PI Totalizer points

    formerpigeek

      We are creating totalizer points to calculate Avg, Min, Max and Total at every 15min, 30min and 1hour, archive is enabled for all of these points. We have following doubts about these totalizer points

       

      1. For 30min we would like to have 15min data as the input and make sure it runs after the 15min data is collected. This means the 30min should have two 15min data as the input. Can we configure this in PI server?

       

      2. The 15min calculated data should consider only the previous 15min values stored for the specified tag source and not the entire data.

       

      3. Suppose if we override any old value in the PI Archive, can we force these Totalizer points to recalculate the Avg, Min, Max and Total upto the last calculated time?

       

       

       

      Thanks & Regards,

       

      Kavita

        • Re: PI Totalizer points
          hanyong

          Hi Kavita

           

          Kavita Enner

          1. For 30min we would like to have 15min data as the input and make sure it runs after the 15min data is collected. This means the 30min should ahve two 15min data as the input. Can we configure this in PI server?

          Just like to clarify what you mean by "have 15min data as the input", are you referring to a Totalizer tag that closes every 15mins?

           

          When we configure Totalizer tag, we usually refer the input as another PI tags that we are performing calculation on. Totalizer does accumulation calculation, meaning that once it is configure, it would use the new snapshot values of the input tags to perform calculation. From what you described, you just need to use the PI tag that gets the 15min data as the input (or source tag if you are using the PI SMT3 plugin to configure).

           

          As to answer your 2nd question, if you configure totalizer to close a calculation every 30 minutes, it would use the new snapshot that is collected for the Input tag for calculation within 30 minutes period for calculation. When 30 minutes is up, it would close the calculation (writing a final result at the end of the 30 minute period) and reset the calculation for the next 30 minutes period. So the final result would be based data collected in the last 15 minutes only.

           

          Because PI Totalizer does accumulation calculation based on snapshot values, there is no recalculation mechanism to perform calculation when the archive data is backfilled or overrided. Recalculation would be available if you are using Performance Equation (PE) and PI ACE.

           

          If you just want to get a summary calculation results at fixed interval, PE can do the same for you. There is a difference using PE and Totalizer to perform such calculations though:

          • Totalizer is more accurate than PE, because it uses snapshot values whereas PE looks in archive value (after compression) for calculation
          • Totalizer shows partial results of the calculation before the calculation period ends whereas PE will give a single result at the end of the period.

           

            • Re: PI Totalizer points
              hanyong

              Hi Kavita,

               

              Have you managed to sort this configuration out? Just like to add on that you can contact our Techsupport Team if you have any doubts about the configuration of Totalizer tags and PE tags.

               

              I am going to shift this post to the PI System Integration forum since this question doesn't involve ProcessBook, ActiveView and Office development.

               

               

                • Re: PI Totalizer points
                  formerpigeek

                  Hi Han Yong,

                   

                  Thanks for the reply it was really helpful for us, also we would like to know if there is a way in AF where in we can configure a attribute to calculate the Min, Max and Avg of a PI Point on a periodic basis and also archive the AF attribute value. We would not like to link this AF attribute to a PI Point to archive the value.

                   

                  Thanks

                   

                  Kavita

                    • Re: PI Totalizer points

                      Kavita Enner

                      we would like to know if there is a way in AF where in we can configure a attribute to calculate the Min, Max and Avg of a PI Point on a periodic basis
                      In the configuration of the PI Point Data Reference for a particular AF Attribute, simply select Minimum, Maximum or Average in the "By Time Range:" setting under "Value retrieval methods".

                       

                      Kavita Enner

                      archive the AF attribute value
                      I'm not sure what your goal is here... if you need to archive data in PI, then send the data directly to the PI Point - and then map an AF Attribute to it. If you have rather static data that further describes an AF Element (where it's an asset, a site, etc.), then just put the value in a static (i.e. without a Data Reference) AF Attribute.

                       

                       

                       

                      On another hand, I would like to kindly invite you to ask these questions to our regular Technical Support team - these are rather "PI Administration" or "End-User" type of questions, whereas vCampus focuses on PI Programming and Integration. They are far better equipped to answer these types of questions, and even do a remote session with you if need be. I also invite you to read the AF User Guide, available on the vCampus Library under the "vCampus PI PRoducts Kit > Server Products" branch.

                       

                      Hope this helps!

                      • Re: PI Totalizer points
                        hanyong

                        Kavita Enner

                        we would like to know if there is a way in AF where in we can configure a attribute to calculate the Min, Max and Avg of a PI Point on a periodic basis and also archive the AF attribute value. We would not like to link this AF attribute to a PI Point to archive the value.

                        Sounds to me like you like to configure AF to do periodic calculation and store archive values in an AFAttribute, instead of configuring Performance Equation/Totalizer/PI ACE calculation to do that and save calculation results in PI tag.

                         

                        To clarify things a bit here, the current version AF is more like a data directory rather than calculation engine or a database/data storage. We use AF Attribute to reference to data from PI server and other database, but AF should be doing minimal data storage, like static values that Steve has mentioned as well. AF provides data for AF Attributes when a AF client request for it (using GetValue() or GetValues() calls).

                         

                        Configuring AF Attribute like what Steve mentioned will allow you to get the calculation results like Min, Max, when AF Client makes the appropriate calls to the AF server, but it is not like the AF server will be performing the calculations by itself and archiving the data.

                         

                        If you want to do periodic calculations and archive the history data for the calculation results, PI + PE/Totalizer/PI ACE is definitely the way to go.

                          • Re: PI Totalizer points
                            formerpigeek

                            Thanks Steve and Hang Yong for your replies, now we have more clarity on what we can do on AF and what not. We will look more into PE/Totalizer/ACE and see where best we can do the Max, Min and Avg calculations on a Periodic basis.

                             

                            Thanks & Regards

                             

                            Kavita