need help getting DPX101 pressure transducers to read correctly in labview

[Anonymous]

hello, i previously posted about some resource errors i was getting,
but i fixed that and now i am simply having trouble getting the
correct through labview.
basically i have no experience with labview, and for this project one
of my professors handed me a box with stuff in it and said here you go
good luck, so i've been learning everything from scratch.

the way the system is laid out is I have an SCC2345 (tan box) with i
believe a PWR02 in it.
There are 4 modules, 2xSCCTC02 and 1 SCCAI01 and 1 SCCAI02. I have
familarized myself with the specs of these modules, and the SCCTC02 is
self explanatory, but the SCCAI0Xs have the following specs.
SCC-AI01
Input Range: +/- 42V
Output Range: +/- 8.4V
Gain: 0.2

SCC-AI02
Input Range: +/- 20V
Output Range: +/- 10V
Gain: 0.5

There are 3 pressure transducers, all Omega DPX101, of the following
pressures: 5000psi, 500psi, 250psi. Each of these is wired into their
own Omega ACC-PS1 power supply.
The ACC-PS1 has the following specs:

ACC-PS1
Excitation Voltage: 18V
Excitation Current: 2mA
Voltage Gain: 1 +/- 2%
Output Signal FS Peak: 10V
Input Power: 2 9V Battery

The system is laid out as exactly shown here:
http://hilltop.bradley.edu/~award/SP/gts.PNG

Using a DAQ assistant, i have it acquire all 5 values at 1000 times
per second and then it updates it to a text file every 100ms.

The pressure sensors each came with calibration sheets and these had a
sensitivity value, and i thought the sensitivity was the "scaling"
value used in the DAQ Assist (5000psi = 1.1mv/psi, 500psi = 10.30 mv/
psi, 250psi = 19.90mv/psi). I entered in these values and i ran some
tests and i was getting a value of 18.6 from labview when a pressure
of 1000psi was applied to the 5000psi sensor. how do i get this to
output 1000 for when 1000psi is applied?

Also, the pressure transducers have a "bias voltage" listed on the
calibration sheets, 8.2 V. Would this have an impact also?

any ideas on what i should do?
is my problem clear enough?

Thanks
-AJ-

[Ed W]

Hi,

Thank you for posting to the NI forums.  You can achieve this functionality by simply adding a custom scale to your voltage task.  Information on this subject can be found in the DAQmx Help by browsing to NI-DAQmx Key Concepts >> Custom Scales.

I hope this helps.  Please post back if you have any further questions.

Best regards,

Ed W.

Applications Engineer

National Instruments