detect value change not caused by user interaction

[robertmodic]

I'm looking for an efficient way to wait on value change of a control or indicator which is not cused by user interaction with a front panel.

Does LabView facilitate a mechanism to detect such value change of a control, indicator or property in terms of events, rather than cycic value checks within a loop which I find sub-optimal.

Particular task I'd like to solve in this fashion is to monitor for a value change of a Control/indicator with an attached Datasocket (connected to OPC) or simply to monitor "Bytes at Port" property of Visa Resource in Serial I/O session.

Robert

[BJD1613]

Why not try using an event structure. You can then create and event that will be triggered on a value change. This should help. Try looking at the example that ship with LV. Hope this helps.

[tbob]

To add to what BJD suggests, using an event structure, in order for the event to be fired programatically, the new value has to be written to the control/indicator's Value(Signaling) property node. Simply wiring a value to an indicator will not fire the value change event. A user changing the value manually will fire the event, but to do it programatically, you have to write to the Value(Signaling) property.