Boolean Crossing PtByPt vi feeding Value (Signalling) property node

[TeraTech]

I want to detect a numerical threshold. I am using the Boolean Crossing PtByPt vi to detect this because I only want it to trigger an event when the value goes from below to above the threshold value. 

This is a simplified example I created using just a Boolean button and indicator. However, the Event Inspector shows that the Value(signaling) is constantly being fired. This seems like the Boolean Crossing PtByPt vi is not working as expected?

[GerdW · Accepted solution]

Hi Tech,

the Event Inspector shows that the Value(signaling) is constantly being fired.

Yes, it is.

This seems like the Boolean Crossing PtByPt vi is not working as expected?

Why do you think so?

You are writing to a "Value (signalling)" property node: this will fire an event regardless if the value has changed or not! (Read the LabVIEW help!)

When you want to fire an event only when the output of BooleanCrossing is TRUE you should use a case structure around the property node…

[wiebe@CARYA · Accepted solution]

You're constantly sending the value (signaling)! Of course you trigger the even constantly. You're signaling the same value, but you are constantly signaling nonetheless. Value (signaling) is fired even if the value did not change. 

If you really want to do this, you need to put the value signaling in a case structure. If changed, send it, if not don't send it.

[TeraTech]

Thanks! I realized it as soon as I walked away from the computer and took my first sip of coffee!  

[wiebe@CARYA]

Thank you for marking solutions! I marked GerdW's post as solution as well, since he said what I said, and actually a bit earlier (our posts crossed).