Reads an event registration refnum for an Event Messenger channel.

You can drop this endpoint on the block diagram by right-clicking an Event Messenger channel terminal or wire and selecting Create»Channel Reader»Event Messenger»Read Event Registration.


icon

Inputs/Outputs

  • cqueuern.png channel —

    channel is the channel wire that connects this endpoint to a writer endpoint.

  • ieventregrn.png event registration refnum —

    event registration refnum returns the event registration refnum that this endpoint reads from the channel. You must wire this output to the dynamic event terminal of an Event structure to receive events from the channel.

    • Unlike the reader endpoints of other channel templates, this reader endpoint must be placed outside the While Loop and can execute only once.

    Use one Event structure to handle events whenever possible. Use the Build Array or Bundle functions to combine multiple event registration refnums for a single Event structure.

    Do not fork the event registration refnums to multiple Event structures. Doing so creates undefined behavior that may result in race conditions or deadlocks in your application.

    Related Information

    Write

    Caveats and Recommendations when Using Events in LabVIEW

    Examples

    Refer to the following example files included with LabVIEW.

    • labview\examples\Channels\Event Messenger\Channel - Event Messenger.lvproj