Differences Between the Input and Output Refnum Value in a LabVIEW Function

Updated Sep 6, 2021

Reported In


  • LabVIEW

Issue Details

I have a LabVIEW application where it is easier to keep using the input Refnum of a SubVI, Property Node, Function, or any similar method instead of using the output terminal to pass the object Refnum to the rest of the application, as shown in the examples of the image below.
  •  Is there any difference between the input Refnum and the output Refnum values?
  • Could this lead to the use of outdated information of the object in the next stages of the LabVIEW application?


A Refnum is a unique identifier that points to an object, such as a file, task, device, or any other object in LabVIEW, so it should never change under the same application scope. The output terminal is provided for wiring convenience, so there is no difference between using the input or the output terminals to pass the Refnum value to the next step in a LabVIEW VI.