Retrigger finite AO on PCIe-6321?

[SebastianM]

Hello!

As the subject indicates, I would like to generate a retriggerable finite-samples analog output on the PCIe-6321 board (X series).

I wired True to the Start:Retriggerable input of the Trigger property node, but the AO task executes only once after it is started (with trigger pulses coming in continuously).

Is there anything else I have to set up?

According to Help, the board should support retriggering, and I do not receive any errors on executing the VI.

Or have I misunderstood the whole concept, and it is only the counters that can be retriggered?

Regards,

Seb

[SebastianM]

ADDENDUM:

Just figured out that the retriggering works fine for a DIGITAL output task.

This is fine in this case, since I need to generate one digital and one analog signal synchronously, anyway.

However, I find it a bit puzzling. Is there an explanation, why the retriggering should work for DO tasks, but not for AO?

Regards,

Sebastian

[Christoph_D]

Hi Sebastian,

I didnt test that myself but if you configured your digital task successfully and you want your analog task synchroniously then you should be able to use the sample clock of the digital task as the sample clock for the analog task. So put "/Dev1/do/SampleClock" as the "Sample Clock Source" of the analog output task.

On why that didnt work for you with the analog output task?:

Hard to tell what you really configured the task. perhaps try it this way:

NI-DAQmx: Retriggering Analog Output Waveform Generation - National Instruments
http://www.ni.com/example/30008/en/

Best regards,

Christoph

[SebastianM]

Hi Christoph

I am synchronously generating one analog and one digital signal.

In the first attempt, I used the AO task as the master and had the DO task follow the AO sample clock. Hence I tried to configure the AO task as retriggerable, which did not work.

Now I use the DO task as master and configure that one as retriggerable, and that works.

Therefore my question: is it normal that retriggering works only for DO tasks and not for AO? Or could I have made a mistake?

Right now, it's part of a rather complex VI, hence I did not post snippets. But if necessary I can implement minimal code for both versions for inspection.

Regards,

Sebastian

PS: I don't quite get the point of the example you linked. To me it reads like the standard instructions for one-time execution of a finite-sample task. 
I now that I can "rearm" a finite-sample task by calling Start once more (e.g. in response to a "task done" event), but this software solution is not reliable on a Windows machine with other software running at the same time. When I tried it, not all trigger pulses were captured, which is not acceptable in this case. Hence the hardware needs to rearm automatically once all samples have be generated.

[Christoph_D · Accepted solution]

Hi Sebastian,

the aforementioned link was a pretty old one one. This one should be better suited:

Community: Generate Multiple Voltage Updates with Retriggerable Trigger - National Instruments
https://decibel.ni.com/content/docs/DOC-11304

To answer your question the X-series (like your PCIe-6321) does support retriggerable analog output. Perhaps you had a little hickup with your code, I cant really tell from the distance.

Best regards,

Christoph

[SebastianM]

Hm, ok, so it should work with analog tasks as well.

When I have time, I will try it once more with a minimal code VI.

thanks for the info!

Sebastian

[Christoph_D]

Thank you. Just post again if it doesnt work out. An example VI is always appreciated in those cases