11-10-2016 02:12 PM
My customer wants to be able to calculate mV/Pascal at various pressures to make sure the response is linear over the range. The problem is I have not been able to find a VI or property node that will give me access to the raw voltage of the input signal when using the DAQMx Pressure Bridge VI, which I would then calculate the actual voltage measured vs Pascals measured. I find it amazing that I can't easily get this raw voltage. I do NOT want to use the Analog measurement and then do all the translation to pressure because that would aliminate all the great stuff the Pressure Bridge Measurement VI takes into account.
11-11-2016 01:13 PM
If the raw analog values are not available (I do not know much about bridge/pressure vi's), could you route the incoming signal to another channel in parallel and monitor the raw voltage values on the 2nd channel?
-AK2DM
11-11-2016 01:38 PM - edited 11-11-2016 01:41 PM
Thanks for the thoughht, but I don't believe that is a practical idea because of the bridge balancing and extra impedance when connecting to another analog input. I also don't think it would be practical to connect to a second bridge input (I am only using 4 of 8 inputs) and do an analog input which would be a basic strain gage measurement - which you can export the raw voltage because of strain-bridge type measurements. The solution would be to give us a property node with this value. I am also steering away from the basic strain gage measurements because pressure sensor manufactuer's do not give you the gage factor or Poisson's ratio which I beleive are required for a proper measurement. That in addition to have to rewrite a significant amount of code to convert strain to pressure and having to manually null and shunt cal.