DAQmx Quirks

[Michael Aivaliotis]

I was on-site recently and was stumped by a few DAQmx issues. I qualify this by saying that i'm running LV7.0 with the DAQmx drivers that came with it. It's possible that these issues have been resolved in the most recent release.

The first problem is the tasks vs. channels. For some reason the task behaves quirky. In a continuous loop situation, when I used a task setup to monitor an input, I would not always get the latest voltage. Sometimes it appeared to display a previous cached value even though I verified that the voltage was changing on the input. I was also calling the same task name in a parallel loop (because i could). When I switched to using a straight global channel name, the problem went away.

The other issue is with the MAX configuration. I wish I had more time to debug this and provide a better solution but... The DAQmx tasks and channel names do not seem to be immeadiatly available when you boot your computer into another user account (under WinXP). My entire debugging was performed under an administrator account. Whenever I booted clean, the DAQ portion of my application would work properly. However, When I booted clean into an Operator account (no administrator access), the DAQ portion of my application would not function. It would not readback correctly. My debugging skills told me to go into MAX and verify the DAQmx tasks and channels. All is required is to expand the (+) icon on the tree to expose the tasks. Then if I go back into my application, it works! Why?

[Randall Thurman]

I have just started looking at the DAQmx configuration & supporting programs. I delayed this change because my acquisition model works well in the traditional DAQ and didn