4 Replies Latest reply on Dec 19, 2011 11:35 PM by Ahmad Fattahi

    Deadband not being applied correctly

    neilg

      Hi All,

       

      I have a PI notification being created programatically. The user can change the deadband on the notification through a UI component and the code updates the config string to update the deadband.

       

      The above is what I am doing but to keep things simpler, if I make changes to the Deadband from PI System Explorer I can see if the values at a PI Point are updated (via a PI Proc. Book display (code to write values to the tag)) the notifications are generated at times and at times they get generated but do not apply the Hysteresis if the value is moving within the hysteresis.

       

      Has anyone else observed this behaviour?

       

       

       

      Version of notifications

        • Re: Deadband not being applied correctly
          Ahmad Fattahi

          Deadband specifies a buffer around the target value that assures that the notification does not prematurely exit the alerting state. The following example shows how Deadband works. Also note that it only applies to <, <=, >, and >= conditions:

           

          5481.diagram_5F00_deadband.png

           

          Now the questions is what exactly you are referring to not happening as expected? Can you clarify if you are seeing more notifications than expected without consideration for the deadband? Is that happening only after you change the deadband?

            • Re: Deadband not being applied correctly
              neilg

              Hi Ahmad,

               

              As per my original post:

               

              "the notifications are generated and at times they get generated but do not apply the Hysteresis if the value is moving within the hysteresis. "

               

              Explaining this further: If I have a condition SourceTag > 75 and apply a deadband of 5 around this and the first value I enter is 69, and then 76 I get a notification at 76. Next I enter 74 and I dont get a notification as expected. Next I enter 76 and I get a notification which is not correct due to the deadband of 5 around the sourcetag. This behaviour is intermittent and at times if works correctly and doesn't send a notification when moving within the hysteresis but then suddenly it starts sending out the notification when it should not.

               

              Cheers, Neil.

               

               

               

               

                • Re: Deadband not being applied correctly
                  Ahmad Fattahi

                  OK I agree with you that some of the things happening here need explanation. However, I don't see this necessarily as a case with the deadband. In your case, the deadband of 5 assures that once your value goes above 75, it does not get out of the alert state until the value gets below 70.

                   

                  I would look into "Time Rule", "Resend Interval", and "Non-Repetition Interval" settings of the notification instead. Each of those can affect the frequency of the notifications being sent when the trigger condition has been active or even how often the trigger condition is being checked to begin with.

                   

                  I hope it helps us move in the right direction. As I see this as a non-programming question, I suggest you follow up the remainder of questions with regular Tech Support as they have better tools to troubleshoot these cases. We will be happy to entertain your programming questions/discussions here