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LabVIEW
Pressure Reading Help
I am graduate student trying to use Labview 2009 to record data from flowmeter (Q, transonic flow meter) and pressure transducers (P1 & P2; range -5 to 5 V, -5 to 20 PSI) connected to a NI USB 6218 BNC daq card.
I have issues converting the voltage from sensor to pressure (mmHg) using mx+b.
If I have no scaling (ie m = 1, b = 0) the waveform shows the correct voltage reading. I verified with a multimeter on the bnc cable at the DAQ connection so I don't believe its an sensor issue. However, if I input a m and b value, then the scaling gets off as the value gets bigger such that 5 PSI/258 mmHg shows up as 400 mmHg and then there is an upper limit were it won't read beyond a certain number (~430 mmHg).
Anyone have thoughts on what the issue could be in my code? I appreciate the help
PS. I also included the pressure calibration code, which I basically input a known pressure and read voltage and program creates the linear line. Occasionally, there seems to be a lag for split second on computer where the value 'read voltage' shows up at 0 despite voltage waveform properly showing. Its more of a nuiscane but if there is a way to fix it, that would be awesome.
