06-08-2010 10:16 AM
I'm currently using the National Instruments 9237 data acquisition device (4-channel input) in my research, and have a question regarding its capabilities.
I'm currently using 2 of the channels to acquire data from two independant load cells, and would like to input a signal to one of the remaining channels that will tell the first 2 channels to stop acquiring data from the load cells. However, from reading the User's Manual available online for the NI 9237, it seems as though there is no communication between the channels within the device.
Does anyone know if it is possible to communicate between input channels to the NI 9237, and if so, is there a way to implement this using LABVIEW?
Thanks,
06-08-2010 12:07 PM
What you are describing is essentially using one of the other channels to perform a "stop trigger" on the other two. This is can be done through a reference trigger normally on a PCI DAQ card as shown in the example below:
http://decibel.ni.com/content/docs/DOC-11792
Unfortunately however the 9237 does not support analog triggering. If you are using the 9237 in a cDAQ chassis you could use the PFI line on the chassis as a digital trigger or use another module as your analog trigger (9205 or 9206 support this).
For all of this I was assuming that you are using DAQmx in LabVIEW, if however you are using a 9237 in a cRIO this is an entirely different conversation and you should be able to accomplish this in custom FPGA programming. Hope this helps!