Complex alarm trigger

Ignition
1

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

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image787×417 19.1 KB

What would be the simplest way of implementing this?

Thanks,

2

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

3

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
2 Likes
4

He might can combine the alarm boolean expression with a transaction group hour meter?
Hour and Event Meters | Ignition User Manual