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Start trigger based upon how long a tag has been at a certain value

Question asked by kbobeck on Feb 28, 2017
Latest reply on Mar 1, 2017 by rdavin

I am trying to create a notification that will trigger when a meter has sent a negative value for more than a certain amount of time. In the screenshot below, some of the values have been negative for some time. It's the tags like the one circled in red that we would be trying to target - recently became negative and has stayed negative, which may indicate an issue that needs attention.

 

 

So far, I have my equation as TimeLT('Meter Reading','t-3d','*',0) but I don't know where to go from here. Theoretically, I would want to do something like TimeLT('Meter Reading','t-3d','*',0) > '2d' meaning it will trigger a notification because it's been negative for more than two days. However, I am not finding a clear way to do this. Another thought I had was to do the alert based upon the number of times a tag had a negative value, in case it was receiving them sporadically rather than for an extended period of time. However, the only function that I see that comes close to doing something like this is NumOfChanges, but that doesn't quite apply here.

 

Any ideas on how I could go about this?

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