Two analog input triggers on PXI-6115

[gmccabe]

Is it possible to have more than one of the analog inputs (AI1 and AI2) setup to trigger the AnalogComparisonEvent? The application is to measure the pulse delay between two different sources using the counter to measure the period of the AnalogComparisonEvent line. If I setup two analog input tasks with analog edge triggers, LabView returns a Error -50103 stating that the specified resource is reserved. This is on a PXI system with LabView 2010 and a PXI-6115.

Thanks,

Garrett

[Craig_]

It sounds like the easiest way to do this would be to add both channels to the same DAQmx task.

[gmccabe]

If I were to create two analog input virtual channels on the same task, what would I wire to the source terminal on the DAQmx trigger block? If I setup two subsequent DAQmx triggers each using one of the AI terminals as sources on the same task, only the last trigger applies. I am looking for both analog inputs to cause a trigger event.

[Craig_]

Oh, alright, I see how that would be an issue and why it's not working. I don't think you can do it that way.

If your application is to calculate the phase angle between the signals it would probably be best to instead simultaneously sample the two channels and compare them in software. Some information on this can be found here:

http://digital.ni.com/public.nsf/allkb/F4BB644ECCA595D886256FFE00722E29

From what I've gathered some of our X-series cards can do this comparison in hardware, but hopefully the software solution will work for your application.