CLAD User Interface & Event Handling Flashcards

What is a Property Node used for in LabVIEW?

Answer: Reading or writing properties of front panel objects and VI settings programmatically

Property Nodes allow programmatic access to attributes of front panel controls, indicators, and VIs, such as visibility, color, or value.

How do you dynamically change the label text of a LabVIEW control at runtime?

Answer: Use a property node targeting the control's Caption.Text property

The Caption.Text property node allows runtime modification of a control's visible label without editing the front panel statically.

What does the 'Value' property of a control accessed via a Property Node do?

Answer: Reads or writes the control's current value without triggering a Value Change event

Reading or writing the Value property via a Property Node silently changes the control's value without generating a Value Change event in the Event Structure.

Which LabVIEW mechanism allows a subVI to communicate back to its caller's front panel controls without using global variables?

Answer: VI Server reference and property nodes

Using VI Server, a subVI can obtain a reference to the calling VI and access its front panel controls via property and invoke nodes.

What is the recommended way to update a front panel indicator from a parallel loop in LabVIEW?

Answer: Use a Queue or Notifier to pass data between loops

Queues or Notifiers safely transfer data between parallel loops, avoiding race conditions that can occur when multiple loops write to a shared local variable simultaneously.

What is the purpose of the 'Invoke Node' in LabVIEW?

Answer: It calls methods on objects or VI references, such as running a VI programmatically

An Invoke Node calls a method (action) on a LabVIEW object reference, such as running a VI, printing a front panel, or scrolling a list.