Problem sending software trigger through PXI backplane (PXIe-1082 Chassis, PXIe-6363 DAQ, PXIe-6544 HS-DIO)

[ideas-moose]

Dear community,

I am trying to implement a (software) PXI backplane trigger on a NI PXIe-1082 chassis with LabView 2015 (32bit) running on a PXIe-8135:

- HS-DIO (PXIe-6544) in slot 2,

- DAQ (PXIe-6363) in slot 4,

- Flex RIO (PXIe-7962R+NI-6583) in slot 3.

The triggering scheme is explained in the attached file "LV-PXItrig-HSDIO-DAQ-overview.jpg".

Scenario 1: DAQ writes analogue signal and sends (software) trigger HS-DIO waveform through backplane, after waveform is complete signals back to DAQ for acquisition.

Scenario 2: Logic pulse on HS-DIO external port triggers HS-DIO waveform, after HS-DIO waveform is complete DAQ triggered for ADC acquisition through backplane.

In principle this breaks down to sending a trigger from module A to B via the PXI backplane. The PXIe-1082 chassis has one trigger bus with 8 lines (PXI_trigX, X=0,..,7) plus a star trigger controlled from slot 2.

I have tied to implement a software trigger but I cannot access the resource upon refreshing and execution, see attachement. Other implementation paths including the DAQmx Connect Terminal / Disconnect Terminal routine have not worked for me either. I am aware on how to connect trigger lines using the VISA property node but I cannot issue a trigger.

Any hints, comments or solutions are appreciated. Thanks!

[ideas-moose]

Let me summarise the above into two questions:

1) How do I connect a dynamic generation (software-generated pulse) in the HS-DIO (PXIe-6544) to a PXI_TRIGx line on the backplane?

2) How do I send a trigger via the backplane using the DAQ (PXIe-6363) when an analogue write occurs?

[JakeA]

Hi ideas-moose,

I've had a look at the code you showed and I'm not sure how it would work. It's my impression that the trigger generation that you're using there will not wait for a user input, so if the Send Trigger! control is not at true at the moment that the case structure executes then it will simply not send the trigger. Perhaps you could upload the VI, but I suggest changing the control to a constant to see whether this is the source of the issue.

Best regards,

[cody_a · Accepted solution]

For Scenario 1, do you want to trigger the HSDIO acquisition to start as soon as the DAQ analog output begins?  You can use DAQmx Export Signal to send the start trigger to one of the PXI Trig lines on the backplane. Then, you'll need to configure your HSDIO acquisition to use a digital start trigger on the same trigger line. Take a look at the "Dynamic Generation Hardware Start Trigger" example in the Example Finder (Help>>Find Examples)

For Scenario 2, it sounds like you are performing a dynamic generation on the HSDIO device when a digital trigger comes in on one of the PFI lines. Once the generation is complete, you want to send a trigger to the DAQ device to begin sampling. If this is the case, you again use a Hardware Start Trigger in your NI-HSDIO task, just as you did for Scenario 1, but use the external trig line as the source, rather than the backplane. There is no hardware event when the generation is done, but you can use a Marker event in scripting mode instead. The "Dynamic Generation with Marker Event" example in the Example Finder gives a good starting place for this type of operation. You'll want to set the output terminal for the event to be a backplane trig line, then point the DAQmx Start Trigger to that same trig line.