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Why is My Boolean Value Property Node a Variant?

Updated Jun 19, 2018

Reported In


  • LabVIEW Base
  • LabVIEW Full

Issue Details

I have a Boolean Control. When I create a Value or Value (Signaling) Property Node, it appears as a variant type. Why is this?


This is because you are trying to create a Property Node from a Boolean control that has latching mechanical action. You cannot read or write Boolean values that are set with a latching mechanical action because race conditions can occur. When a Boolean is set to a latching mechanical action, it means that after you change the value of the Boolean, it will change back to the default once the VI reads its value. Therefore, depending on when the value of the Boolean is read by the VI or by the property node, you may miss a change in the value.

Try changing the mechanical action of your Boolean control to switching. This will allow you to use both the Value and Value (Signaling) Property Nodes, which you will notice will now be of type Boolean instead of Variant. A Boolean with a switching mechanical action will not revert back to default value when pressed only once. For information about the mechanical actions of a Boolean please look at the related links.