Curt,
It returns an error code. If you set the ExceptionOnError property to true, then an exception is thrown.
0 means that there was no error. If it is a negative number, the number indicates an error code, if it is positive, then its a warning.
If you get an error, you can use the NI-DAQ error codes topic, to figure out what the error means, or search the Measurement studio help.
Hope this helps. Please let me know if you have more questions.
Nandan Dharwadker
Staff Software Engineer
Measurement Studio Hardware Team