Measuring Multiple Voltages in LabView w/USB 6001
I'm trying to set up my LabView VI + my USB 6001 I/O box to be able to read multiple independent voltages at once, while also outputting a single constant voltage.
I've successfully gotten my USB box to output the voltage I want while reading back a single voltage, but so far I've been unable to read back more than one voltage (and if I do, the two voltages seem to be co-dependent on one another in some way).
Here's a screenshot of my VI:
Everything to the right of the screenshot window should be unimportant to the question.
If anyone is curious, this is to drive multiple LVDT's and read back their respective voltages.
Thank you all for your help!
Look at your DAQ's manual, especially the pages I noted below. http://www.ni.com/pdf/manuals/374259a.pdf
Page 11
All the AI channels get multiplexed, and the low-side reference can be switched (RSE vs. differential). So the two channels you're sampling require both of those to switch. It might be a settling issue where the ADC is taking a sample before the input value is stable.
To verify this, try using using the same low side (differential or RSE) on both channels. Also try slowing down your sample rate (but your 1 kHz should already be slow enough...).
Page 14
Check this to make sure you have everything connected and grounded correctly.
Page 18
Check this for more details about switching between 2 sources quickly.