15 Replies Latest reply on Aug 15, 2013 5:04 PM by tim.read

    Timeweighted change date in PI Tag attributes

    tim.read

      We've developed a tool that pulls updates from any tag on the PI server and we store all of the pi tag attributes in a csv file.  We noticed one instance where the changedate value included "timeweighted".  How would "timeweighted" appear in the pi tag attributes?

        • Re: Timeweighted change date in PI Tag attributes
          mhamel

          @Tim: AFAIK, there is no timeweighted attribute but a CalcMode attribute of a totalizer point (derived from a totalizer point class) can have 'timeweighted' as value. I imagine this is what the tool is reporting about.

           

          This is the value of attribute and not the attribute name itself.

           

          I hope this helps!

            • Re: Timeweighted change date in PI Tag attributes
              tim.read

              Thanks Mathieu,  so the Changedate value actually contained a value of "timeweighted, 7/22/2013 4:25:51 PM".  Our expected changedate value was only 7/22/2013 4:25:51 PM.  What would cause the 'timeweighted' to appear?

                • Re: Timeweighted change date in PI Tag attributes
                  mhamel

                  @Tim: I couldn't think of something different than a configuration change on that PI Point. Can you get the value of the changer attribute, this should tell you would made the change if different from the last time.

                   

                  Is the ptsecurity attribute is defined correctly to allow only administrators to change the configuration?

                  • Re: Timeweighted change date in PI Tag attributes

                    Hello Tim,

                     

                    Points can belong to different Point classes and different point classes have different point attributes.

                     

                    Tags that are serviced by the PI Totalizer subsystem are member of the "Totalizer" point class which has an attribute "CalcMode" that I believe is unique for "Totalizer" point class - at least with the default point classes.

                     

                    When retrieving the configuration of "Totalizer" tags using PI SMT add-in for Microsoft Excel, I see "CalcMode" on the left hand side besides "changedate" attribute.

                     

                    Is it possible the information within "CalcMode" has been merged into "changedate" within your application?

                     

                    Because all point classes use the attributes from "Base" class plus additional ones, I suggest storing configuration data separated by point classes within your application - if this makes sense to you.

                     

                    What's the purpose of your application? Are you auditing the point table?

                      • Re: Timeweighted change date in PI Tag attributes
                        tim.read

                        So our application is a tool that tunes PI Tags but a feature in the application is keeping track tags that have been added/edited and what was added/edited

                          • Re: Timeweighted change date in PI Tag attributes
                            Marcos Vainer Loeff

                            Hello Tim,

                             

                            If you could please attach a spreadsheet  generated using PI Tag Configurator, which is an add-in of Excel, with the configuration of this specific tag, we might be able to help you better.

                             

                            If you don´t know how to do that, please let us know and we will help you!

                              • Re: Timeweighted change date in PI Tag attributes
                                tim.read

                                small problem with that is that i cant reproduce this scenario.  one of our customers found this issue.  I just would like to know some possibilities where "Timewheighted" would appear in the changedate attribute of a tag.  From the discussion thus far it seems like it could be stemming from a Totalizator point class.

                                  • Re: Timeweighted change date in PI Tag attributes
                                    tim.read

                                    i'll see what i can grab from the customer in terms of the tag configuration of the tag in question

                                      • Re: Timeweighted change date in PI Tag attributes
                                        tim.read

                                        What is the purpose of the Totalizer point class, what would be a scenario where someone would use this class?

                                          • Re: Timeweighted change date in PI Tag attributes

                                            Hi Tim,

                                             

                                            I can only assume that your "tuning" application changes tag attributes used by Exception and Compression. I understand the motivation for the attempt to make a PI system managers life easier. However to apply good Exception and Compression settings it's not only necessary to have a good understanding how Exception and Compression works. Rather one also needs a good understanding of the process data and about the "interface" collecting the data and servicing tags in PI. This said, I wouldn't trust into any kind of automation but prefer maintaining settings manually. This doesn't imply to find a good setting for each individual tag or that each individual tag needs to be set up manually.

                                             

                                            Based on data types and value ranges, basic settings can be suggested that will deliver good results in the majority of cases and make a fine tuning necessary only for a smaller percentage of tags only i.e. those supposed to record pretty busy signals. I consider reviewing recorded data a necessary requirement. Asking the "data users" for their opinion is a good practice. Signals that require changes can usually be grouped, so settings need to be evaluated for a smaller subset of tags only and could than be applied for others of the same kind. PI SMT Tag Builder add-in for Microsoft Excel is my preferred tool for this kind of work.

                                             

                                            Tim Read

                                            What is the purpose of the Totalizer point class, what would be a scenario where someone would use this class?

                                             

                                            PI Totalizer Subsystem is a calculation engine belonging to the so called PI Server applications. Because of the specific configuration requirements (additional attributes) of PI Totalizer Subsystem all belonging tags are using "Totalizer" point class. I recommend not treating tags with pointclass = "Totalizer" with your "tuning" application since this may have a direct impact on calculation results. PI Totalizer may report status "Configure", "Bad Sample" or similar because of the changed configuration until the next reset (clock scheduled or event triggered) occurs.