Triggering when grouping PXIe cards into a single task

[GregFreeman]

I have a single AI task the includes channels on 2 different PXIe cards, one in slot 2 one in slot 3. Slot 11 has my counter that's being used as a trigger. What I have noticed is if I route all lines away from segment 2 and then use connect terminals to connect my PXI1Slot11/ctr0 to my PXI1Slot2/trig_0 everything is fine and data is acquired. But, if I route PXI1Slot11/ctr0 to my PXI1Slot3/trig_0 the code won't run because the trigger isn't received by PXI1Slot2. I'm just trying to get an understanding for what is happening in the backplane. Does the trigger always have to be connected to the lowest slot in the task? This is important for our dynamic configuration based on which cards the engineer is using for a particular test. If I remove the channels in slot 2 from the task and route the counter to trig_0 in slot 3 then again things work fine. This isn't really an issue because I can get the tasks to configure and run, but instead is more of a general question on what the hardware is doing.

[warEagle12]

Hi Greg,

What chassis and controllers are you using? Is your chassis using a star trigger? Here are some links that might be helpful:

- More information about the Star Trigger: http://digital.ni.com/public.nsf/allkb/36C85640D7F916B186256A8B007742DA

http://zone.ni.com/reference/en-XX/help/370524L-01/nisignal_generators_help/integration_pxi_star_tri...

- Have you configured your trigger routes in MAX? http://digital.ni.com/public.nsf/allkb/BC3A1609E4CB2D6B862572C3005A742B?OpenDocument

- This document explains how to configure the PXI Trigger Routing: http://digital.ni.com/public.nsf/allkb/CA9A49FA50393C4186256DC200774E2B?OpenDocument

- An article about how NI PXI Boards Map to PXI Backplane: http://digital.ni.com/public.nsf/allkb/F4AD3B87DC8CD62E862571E3007042E5?OpenDocument

Thanks!

[GregFreeman]

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@warEagle12 wrote:

Hi Greg,

What chassis and controllers are you using? Is your chassis using a star trigger? Here are some links that might be helpful:

- More information about the Star Trigger: http://digital.ni.com/public.nsf/allkb/36C85640D7F916B186256A8B007742DA

http://zone.ni.com/reference/en-XX/help/370524L-01/nisignal_generators_help/integration_pxi_star_tri...

- Have you configured your trigger routes in MAX? http://digital.ni.com/public.nsf/allkb/BC3A1609E4CB2D6B862572C3005A742B?OpenDocument

- This document explains how to configure the PXI Trigger Routing: http://digital.ni.com/public.nsf/allkb/CA9A49FA50393C4186256DC200774E2B?OpenDocument

- An article about how NI PXI Boards Map to PXI Backplane: http://digital.ni.com/public.nsf/allkb/F4AD3B87DC8CD62E862571E3007042E5?OpenDocument

Thanks!

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Stephanie,

1) I'm not using the star trigger, as propogation delay is not an issue for this application

2&3) I mention in my original question I have routed the trigger lines. I also mention I have gotten the triggering to work

4) This doesn't really answer my question.

My question is very specific, not about general routing. I'll rephrase my question wIthout all the mumbojumbo in my first post, most of which is just background and doesn't give much info about what I'm wondering and probably just causes confusion:

If I have an AI read task that includes channels on multiple PXIe 4331 cards in a segmented 18 slot PXI chassis (I forget the number, 1085 maybe), I have to connect my counter to <first card in task>/trig_0 in order for triggering to work. If I route the counter to, say, <second card in task>/trig_0 the task won't trigger. 

[warEagle12]

Hi Greg,

I'm sorry I didn't understand your question right the first time! If you flip the order of the cards specified within the task will it behave correctly?

Thanks!

[Mcdan]

Greg,

What does your multi-device task specify as the start trigger source?  Is there a reason you need to explicitly connect terminals rather than setting the task to use PXI1Slot11/ctr0 directly?

Dan

[GregFreeman]

Dan,

When I try to connect PXI1Slot11/ctr0 to the start trigger it gives me a broken wire. I'm assuming the Start trigger VI cannot take a strict counter type DAQmx refnum as the input. I assumed I had to output the counter on a trigger line (i.e. slot11/trig_0, then connect slot11/trig_0 to slot2/trig_0. Suggestions?

[GregFreeman]

Excuse my naivity with regards to DAQmx guys. I have some results. First, Dan, you are right, I can just have ctr0 output on slot11/trig_0 then use slot11/trig_0 as the start trigger. No connecting of terminals needed.

Stephanie, you were correct. If I change the order of the devices in the task, then I can use PXI1Slot3/trig_0 as the start trigger. However, since I can jsut use slot11/trig_0 and let the driver handle it all, this isn't really necessary now.

Anyways, thanks! I had tried so many different permutations to get everything to work that I couldn't necessarily remember why certain things were there. I didn't want to remove them due to the whole if-it-aint-broke-don't-fix-it mantra.