Complex alarm trigger

Hi all,

I want to setup an alarm that will trigger when a process value has been out of range accumulatively for more than a set percentage of an hour. Note the hour window is also moving

Here is an example

What would be the simplest way of implementing this?

Thanks,

Sounds like you need to historize this tag and run a tag history query to get your accumulation.

Yeah, I don't think there is any "simple" way to do this.

Maybe:

  • create a boolean expression tag that is true when the process value is >= limit, false otherwise
  • historize this expression tag
  • periodically (timer script?) run a tag history query on this tag, using aggregation mode duration on (or duration off if you flip the logic)
  • if the duration on > 40% of an hour, set another boolean memory tag on which you've defined an alarm
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He might can combine the alarm boolean expression with a transaction group hour meter?
Hour and Event Meters | Ignition User Manual