This example demonstrates how to use an event structure to post a message and pass data to the event structure using the PostLVUserEvent() function. The VI calls the dll using the Call Library Function Node, and the dll passes three messages to the event structure. A dialog window displays the data and remains open for 2 seconds. The dll is called in its own thread so it does not hang the UI thread.
Example code from the Example Code Exchange in the NI Community is licensed with the MIT license.