Understanding Error "-200846" DIDO in Nibble mode

[Der_schorsch]

Hey everyone,

the goal is to use a 9401 to record and output digital lines. The digital line is used to trigger a camera, thus should be synchronized to the digital input. The point is I want to record only a finite number of samples at a given sampling rate. Using the example for the DIDO in nibble mode i played around with it and tryed to modify it to my needs.

However I keep running into Error 200846 when trying to do so. The error is solved if the autostart property of write node is set to true. But this starts the write task before the read task. I checked this by wiring the line in and line out elements together. And ideally, this should record 190 false values and one true value. But it only records true values, which in my eyes confirms my idea.

Or is my understanding here wrong? Any help would be greatly appreciated

[Der_schorsch · Accepted solution]

Okay,

after a freak strain of thought I came up with the solution, just posting this in case somebody else had the same problem: You have to define a timing. This is easily achieved by adding the DQmx Timing VI to the Output Task and defining the source as di/SampleClock with the the same acquisition rate and number of samples.

I was mislead by my readings and measurement, as I had forgotten to wait till the output task was done until stopping and clearing it.