Hello jiv,
there is no hardware trigger on the 9215 module. That means that all triggering has to be done in software. You have to acuire all channels all the time and decide afterwards whether you keep the data or just drop it. With daqmx you can use the VI "Analog SW Trigger" to dio this decision. It is located under LabVIEW\examples\dambxbase\dynamic\ai.
Ingo Schumacher
Systems Engineering Manager CEERNational Instruments Germany