DAQ Assistant Configure scale for pressure transducer

[NileSTC3]

Hello All,

I am trying to measure pressure using DAQ assistant in LabVIEW. My sensor is XTL-123G-190.pdf (datasheet attached) and the calibration sheet as well.

I am having trouble with selecting the correct first and second values for both the physical and electrical attributes.

I tried 

Electrical

1st- 0

2nd-10

Physical

1st-0

2nd-100

The sensor sensitivity is 1.992 mV/psi excited at 10v.

Even at ambient conditions I get bad values.

Am i reading the datasheet wrong?

[Ahmed99]

Hello what is the values appear ? i mean bad measures ? where you got the sensor ? which country you work on it?

[NileSTC3]

I am getting values such as 28-30psi for ambient which is normally 14.6 here. The values are definitely bad. I have kept the sensor on my table exposed to normal dry air.

[santo_13]

Your pressure sensor sensitivity is 2.003mV/PSI

Please share the DAQmx configuration you have tried and electrical connection used.

[NileSTC3]

This is the configuration as attached. Where do I add the sensitivity of the sensor?

The sensor is powered by the NI-9237 card at 10v

[santo_13]

You've chosen an incorrect channel type, it is not a bridge-type sensor.

You've to use an Analog Input voltage because your pressure sensor outputs an analog voltage proportional to the pressure, unlike other pressure sensors whose resistance varies proportional to the pressue.

1. Create an Analog Input Voltage task
2. Configure appropriate min, max voltage values
3. Create a new custom scale and configure it to be linear
4. Set the 2.003mV/PSI as the slope
5. Set the scaled unit to PSI

Now the DAQ measures voltage from the pressure sensor and scales it and returns the measurement in PSI

Important note - I do not recommend using DAQ Assistant unless you want to test something quick, if this is going to be part of larger automation or experiment, better learn to use DAQmx drivers

[NileSTC3]

Hello Santhosh,

Thank you for your response, however I just realized while running LV that the Ni-9237 does not support voltage, it is strain card and hence only takes in bridge inputs.

Can I configure the card to give me the raw voltage output to later convert it to psi manually.

[santo_13 · Accepted solution]

As per my understanding, you cannot operate that card in AI mode, it has to be a bridge type sensor since the ADC uses the excitation as a reference.

Unfortunately, you are having an incompatible sensor and instrument combination.