Synchronize AI/AO Clocks with multiple AI in parallel

[Telleurium]

I would like to synchronize my AI and AO to run on the same clock and have my AO start with a trigger from the AI start.  All works beautifully except when I have another process running in parallel.  I'm using the 9178 cDAQ chassis and I have one low resolution AI (9201) that runs in the background monitoring for alarm conditions.  I want this to run in parallel to my DAQ vi.

In the DAQ vi the AI (9222) starts and triggers the AO (9263), the AO clock is referenced to Dev1/ai/SampleClock and the start trigger is referenced to /Dev1/ai/StartTrigger

The problem seems to be that if the 9201 is collecting AI data then my AO is actually running at this clock rate instead of the 9222 (since the 9201 is always running in the background, the AO saw this first)

How do I tell the AO (9263) to run with the 9222 AI clock and trigger rather than the 9201 AI?  I think I'm not understanding how the chassis works with the modules...

Gracias.

[Izzzzz · Accepted solution]

Hello Telleurium, 

The quick answer is to specifically call out the timing engine and the timing engine trigger. This will ensure that the 9263 and the 9222 are synchronized. Please take a look at the example below which I specifically call out the teo timing engine. 

A more detailed explanaiton of what is happening is that the 9201 is grabbing the ai timing engine first (which means it is now associated with the ai sample clock, and ai trigger) thus you are seeing that the 9263 is synchronized to the 9201. 

Best Regards,

Izzy O.

Applications Engineer

National Instruments

www.ni.com/support

P.S. On further notice it would probably be easier to point the 9201 to a different timing engine. 

[Telleurium]

I couldn't immediately get this solution to work but I didn't spend much time since I decided it was easier to run the AI 9222 off the AO clock instead.  Then no conflict with the other AI device.

Thanks!