3 Replies Latest reply on Jan 16, 2013 2:31 PM by gkrueger

    PE Trigger on using multiple tags as triggers

    gkrueger

      Does anyone know a way to get a PE to trigger using more than one trigger tag (maximum of 4 in my case)?  

       

      I'm thinking I might need a separate PE which looks at the multiple tags and then use that PE as the trigger for the other PE.  

       

      That's starting to get a bit complicated though, so I wanted to see if anyone knew a simpler way or has done something like this before. 

       

      BTW, the trigger tags I want to use are string tags coming from an OPC interface.

       

      Thanks,

       

      Greg

        • Re: PE Trigger on using multiple tags as triggers
          Ahmad Fattahi

          I agree that aggregating the trigger conditions in one PE, to be used as the master trigger PI tag, can easily get tricky. As far as I know the best way out of this would be using PI ACE.

            • Re: PE Trigger on using multiple tags as triggers
              fbatista

              I agree with Ahmad that the best way would be using PI ACE. However, if you still want to use PE, you could use the master PE as your trigger tag. That master PE would be a clock-based tag to be evaluated very frequently, let's say, every second or < 1s. Then you check if each of your 4 trigger tags have received a new value (using the function PrevEvent). If any of these tags has received a new value, then your master PE would generate a new output, that would trigger your final calculated tag. Of course, this method is not perfect, because you cannot use the actual timestamp of your 4 triggers tags as the timestamp in your master PE tag (because it is clock based). It may be a problem when the PI Server receives the trigger values that were previously accumulated in the interface buffer.