Wiring an Omega Pressure Transducer to NI USB-6229

[mr.dtran]

Details:

Transducer: OMEGA PX03C1-100G5T Specs

Hardware: NI USB-6229

Wiring:

Pin A (+OUT) of the sensor goes to AI2.

Pin B (-OUT) of the sensor goes to AI10.

Pin C (-INPUT (EXC)) of the sensor goes to a 24V power supply negative (has no ground).

Pin D (+INPUT (EXC)) of the sensor goes to a 24V power supply positive (has no ground).

Hi All,

I am interfacing a 0-5V Omega pressure transducer with the NI USB-6229 module in the differential configuration but the value I am seeing in MAX is not what I expected. I have reviewed the "Field Wiring and Noise Considerations for Analog Signals" white paper, http://www.ni.com/white-paper/3344/en/, and connected my sensor accordingly but I am still struggling.

Issue: In MAX, the voltage measured is not the same as my multimeter when measuring across the -OUT and +OUT of the sensor. It appears that my voltage signal is capping out at 2.4-2.5V in MAX, with or without the bias resistors. With a multimeter, my measurement across the outputs reads up to 5V. I switched to a different pair of differential inputs with no success. Hopefully, someone can help me figure out what is wrong.

Regards,

David

[tobriant]

Hi David,

Can you send in a screenshot of the Test Panel you're using in NI-MAX so I can check out your configuration settings?  If you're confident your wiring matches the M-Series DAQ User Manual and the Field Wiring and Noise Considerations Guide, a good next step is to check the software settings.

[mr.dtran]

Hi Tyler,

The following are the screenshots I was able to collect. Is there a particular setting that you would want to see?

NI MAX Test Panel w/ highest value recorded

NI MAX About

Best Regards,

David

[_Bryan]

---

Wiring:

Pin A (+OUT) of the sensor goes to AI2.

Pin B (-OUT) of the sensor goes to AI10.

Pin C (-INPUT (EXC)) of the sensor goes to a 24V power supply negative (has no ground).

Pin E (+INPUT (EXC)) of the sensor goes to a 24V power supply positive (has no ground).

---

Are you sure about the wiring?  The spec sheet you linked to says:

A: + Output

B: - Output

C: - Input

😧 + Input

[mr.dtran]

Bryan,

Nice catch. Just a typo on my end. 

The wiring is correct and is connected as follows:

Pin A (+OUT) of the sensor goes to AI2.

Pin B (-OUT) of the sensor goes to AI10.

Pin C (-INPUT (EXC)) of the sensor goes to a 24V power supply negative (has no ground).

Pin D (+INPUT (EXC)) of the sensor goes to a 24V power supply positive (has no ground).

All connections confirmed with a continuity test.

[_Bryan]

What happens if you connect a 9v battery to AI2 (Terminal 7) and AI10(Terminal 8)?  Does the test panel read about 9v?

[mr.dtran]

Bryan,

Please see the screenshot below. The test panel reads a little over 9v on AI2 when I connect the battery. It looks like the input is working, though. Any other ideas?

Testing with a 9v battery

Best Regards,

David

[_Bryan]

Have you tried setting the channel as RSE or NRSE?

When connected to the transducer does the test panel voltage change with pressure or just sit at ~2 volts?  Does the test panel voltage change when you read the voltage with the multimeter?

[mr.dtran · Accepted solution]

Bryan,

Thank you for your help. The problem was with the power supply and not the wiring or settings. The wall adapter we used is 24VDC/500mA, but the transducer/NI setup did not like it. I switched to a bench power supply and the voltage began reading correctly on the test panel using the DIFF mode.

Best Regards,

David