04-26-2010 09:28 PM
So, I have a t-shirt from NI week that says I can do more with LabVIEW than you...but I'm stumped here.
I created a simple VI that reads 14 differential inputs and continuously plots the waveforms at 10Hz. I used the DAQ assistant to set up the chanels and then the signal manipulation vi (configured as 2d array of scalars, columns are channels) to break out the data. Using a different Index array function for each channel, I access each channel and scale the data as necessary. Then, the data is bundled and run to a cluster chart.
I am finding that after running the VI for a few hours, the channels are getting crossed. It's the correct data being displayed, but on the wrong channel. I probed the block diagram and confirmed that the data somehow is showing up in a different channel (e.g. a signal physically on AI0 shows up if I'm Indexing column 4 of the array when it was originally at index 0 as expected). It's as if the scanning order changes and is randomized. Interestingly, if I close LabVIEW and start over, everything works properly again for a little while.
I am not seeing any noise or other wierdness.
In terms of set-up, It's an SCXI 1000 chassis with 1102 accessory. This feeds a PCI-6281 multifunction DAQ. Running 8.2.1 on this particular machine.
Any ideas?
Thanks,
-Jesse
04-27-2010 04:16 PM
Does anybody have any ideas on this? it's a wierd problem. Does anyone know of any compatibility issues between M-Series DAQ's and older SCXI chassis?
Thanks!!
-JD
04-27-2010 04:25 PM
Just a shot in the dark but have you ruled out ghosting?
Just trying to help.