Watchdog on a NI 9476 Digital Output module on a cDAQ-9189 chassis (LabVIEW 2021)

[MartinP]

I'm trying to make a Watchdog function on a 32 channel DO module, that I also use to write to regularly.

Unfortunately I have no good example files to look at, and I find the documentation for these features not ideal.

I have been unsuccessful so far, I make the watchdog trigger, but it does not put the DO output lines

to their expiration states.

I have tries many variations over the theme as shown in the attached demo of the problem,

also one where I only operate with one single task, but again, unsuccessful.

PS; the simulated cDAQ hardware does not support Watchdog, so this can only be tested towards real hardware.

[MartinP · Accepted solution]

I have established that LabVIEW 2021 has a bug here that makes the cDAQ module fail in going to its expirations state. When upgrading the program to LabVIEW 2025, the same code works as it should, and the output signal do go to their expiration state.

[rolfk]

Almost certainly the bug has little to do with the LabVIEW version but a lot with the DAQmx version. You can install (up to a certain point) newer DAQmx version into older LabVIEW versions. The latest DAQmx version supporting LabVIEW 2021 would be DAQmx 2024 Q4, which might or might not have fixed the bug you ran into.