DAQ assistant triggering problems

[Dennis D.]

I am using DAQmx version 7.2 with a SCC 2345 board connected to a 6052E. I need to be able to use an external interrupt to start and stop data acquisition but when I run my Labview task, I either get an 200274 error or a 200284 error depending on exactly how I set the trigger condition in the DAQ assistant. I realize that these errors basically mean that the FIFO buffers are being overfilled (takes about 10 seconds) but I can’t figure out what to do to correct the problem. Any help would be appreciated.

[e-Cash-Money]

Hello Dennis,

I was unable to find information on the 200274 error. Could you double-check to make sure that this is the correct error code?
Exactly what configurations of the trigger affect when you get the 200274 error and the 200284 error?
200284 is often generated because a digital trigger was never received. You can try increasing the timeout value (an input on the DAQ assistant) if you need more time to wait for the trigger. Also, verify that a) you have your external trigger signal connected to the correct pin and b) the trigger signal is actually being generated.

Thanks!
E.Lee

[Dennis D.]

I finally realized that I needed to set the timeout on the DAQ assistant to -1, which got rid of the error. The trigger appears to work but the whole VI seems to be sluggish and does not want to respond to the stop button any more. I have another question. When I select N Samples under Acquistion Mode and then choose for example 10000, how do I know when the acquisition is completed? Thanks for your help so far Lee.

[e-Cash-Money]

Hello Dennis,

1) The reason why the VI seems sluggish and won't respond to the stop button is because the VI will not check to see if the stop button was pressed until you are finished with your data acquisition. There are ways around this, but we will have to abandon the DAQ assistant to do so. The DAQ assistant is meant to be easy and quick to use, not highly configurable. In order to have a highly configurable system, we will have to use the normal DAQmx VIs. This is a pretty easy transition and not too much work at all! The following link has information on how to implement this.
http://forums.ni.com/ni/board/message?board.id=250&message.id=11601&requireLogin=False

2) If you are using the DAQ assistant to do an N samples read of 10000 samples, the DAQ assistant will return all 10000 samples at its output. So the way to know that you have finished acquiring 10000 samples is that the DAQ assistant will be finished executing.

Let me know if you have any other questions!

Take care,
E.Lee