DAQ assistant not updating output signal

[joaoanf]

Hello everyone,

I'm trying to generate and output to the board just a simple digital PWM signal. I followed exactly this example:

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YGK5CAO&l=en-CA

The only problem here with this setup, is that the DAQ Assistant is not able to update the signal that it is outputting mid-running; no matter the adjustments done to the duty cycle or to or the frequency, it only updates the output signal once I stop and run again. Note: the digital waveform indicator updates correctly and immediately, so the issue is really with the DAQ Assistant. Using the "N samples" mode allows it to update, but it creates a large discontinuity in the signal, which is undesirable.

I found someone with a similar problem:

https://forums.ni.com/t5/LabVIEW/DAQ-Assistant-in-subvi-not-updating-output-to-DAQ-board-with/m-p/89...

But this thread is from 13 years ago: is this still a bug, and is my only option to use lower-level DAQmx functions?

I'm using LabVIEW 2018, a cDAQ9188, and a NI 9401 card. Thanks in advance!

[santo_13 · Accepted solution]

I would strongly recommend going the DAQmx driver route and ditching the DAQ Assistant.