Hi,

I'm struggling with this question for a long time.

We are monitoring Gas analysers and the moment an analyser value passes a certain range, it is a rule this analyser has to be checked immidiatly.

Now we monitor this by looking at trends and and see if the analyser(s) has been exceeding the max limit over the precious period of 8 hours.

It would be helpfull if a calculation Tag would show automatically a total count of events over the last 8 hours (every event should count as one, does not matter how long that event was).

Example:

Analyser: AI-301

Max limit: 20

Events that happend from now and 8 hours back:

Thanks in advance.

André

Hi Andre,

Thanks for on PI Square.

There are a lot of ways to do this. Since you are after a performance equation, I'll provide that method. You'll need to create 2 performance equations. The 1st performance equation will filter your raw tag using the following

If 'SourceTag'>Limit then 'SourceTag' else NoOutput()This filtered tag will be naturally scheduled which means that values are filtered the moment a new event comes into the PI Data Archive.

The second performance equation tag will calculate the number of filtered events over the last 8 hours using the following syntax:

EventCount('FilteredTag','*-8h', '*')I would recommend setting this performance equation tag to be periodic so that you have a more real-time analysis of what is happening to your equipment.

Please give this a shot and let me know if that works for you.

~Jesse