Calibration on DAQ Express

[a78kim]

Hi, I'm really new to DAQExpress and I'm trying to measure pressure drop of a channel. 

The analogue signal shows negative values and then positive values as I increase the flow rate. I'm not sure that this is caused by my channel design or Do I need to set zero or calibrate it before tests? If I need to, how can I do that? 

Thank you! 

[WaiLee]

Hi, it could be few possible reasons:

1.There is one thing to concern when troubleshoot the unexpected I/O results which is correct terminal connections. Make sure terminal connections are secure. Check the DAQ device pinouts and sensor manuals to make sure the sensor or signal is wired to the correct DAQ device terminals. For example, if you see a result of -5V when you expected +5V, you might have the + and - terminal wiring reversed. 

2. Wrong data type representation in your LabVIEW code such as U32 (unsigned integer) instead of I32 (signed integer).

3. Didn't configure the input range of the measurement (Try to make 0 to +V instead of -V to +V)

[a78kim]

Thanks a lot for the comments.

Do you know how I can change the range of the input from '-V to +V' to '0 to +V' in DAQ Express?

Since the measured voltage changes as the flow rate changes, I believe it measures the pressure drop, but I cannot trust the absolute value of the voltage. The increment could have a meaning though.

[WaiLee]

You can try have a look on this link which show steps on how to configure it at the max and min section: https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x0QHCAY&l=en-US