IMAQ 1408 + DAQ cards crashing when loop iteration 1

Question

I have a problem trying to run some code which outputs a synchronised analog and digital pattern using the PCI-DIO-32HS and PCI-6713 DAQ cards which triggers an external analog camera. The images from the camera are then read via the IMAQ 1408 frame grabbing card.
When I run the code once, it executes successfully every time. If, however, I select 'run continuously', or alternatively place a FOR-loop around the pattern output and image collection, the computer executes the pattern once, then completely freezes the computer, requiring a hard reboot of the computer.
I have attempted to add wait times at various points through the code, however even if I place 10s delays in the loop (the pattern takes around 1s) the computer hangs and crashes. Running the code by repeatedly clicking 'run' however works every time, with no error or crashes.
Is there any way to extract or trace the error causing this behaviour - the issue must be with the IMAQ drivers, however I cannot see what is different between running the VI manually 10 times in a row, and running it continuously with a wait to prevent it running at full speed. Any advice for debugging this error would be much appreciated. I have attached the code with subVIs necessary to reproduce the error.
Attachments:
JAI_Testing.zip ‏841 KB

Answer 1

Hi Fan Wu,
You're right that you only have two counters on your USB DAQ device. If we limit the problem to only one channel, then I would recommend using the counter because it sounds like you're creating a pulse train of known parameters. Since the counters use a fast timebase (if you're using Mseries you're using an 80MHz clock), you'll get very predictable performance at 1ms of interest.
The other way to do this (since you'll need more channels) is to use a counter to setup a timing engine. A simple pulse train with 50% duty cycle and whatever frequency you're interested in (sounds like 1kHz) can be used as your DI/O timing clock. You can then create a digital waveform with the characteristics you are interested in and write that to your buffer. With your Digital task correlated to your counter output, you can output this waveform at the rate of your counter output.
While this is NOT the end application you are looking to write, this example has some great parallels to what you are trying to do. It illustrates creating a clock with the counter and then writing a digital waveform to correlate to that clock.
http://zone.ni.com/devzone/cda/epd/p/id/3687
PBear
NI RF