DAQmx Pressure Reading Issues

[Dennis_Knutson]

Please keep it simple. You should be seeing 8 available channels (0-7) because that is how many channels are on the daq device. Do NOT choose a current measurement. Just select differential voltage at this time and see if you get voltage changes. Scaling can be done per the sensor's data sheet but first you need to get a reading on volts.

[StuartWotherspoon]

Sorry Dennis, rookie mistake. I see Ch 0-7 so that's 8 all in all.

In terms of selecting channels I've got 4 wired in - so would I be selecting AI0 AI1 AI2 AI3 and selecting linear? as that's what's I'm needing to see? I do get volt changes on the multimeter as I increass pressure.

What you're saying makes sense, I think working in isolation with it I was confusing myself. It's good to get to air some of it with people that know their way around it.

[crossrulz · Accepted solution]

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StuartWotherspoon wrote:

In terms of selecting channels I've got 4 wired in - so would I be selecting AI0 AI1 AI2 AI3 and selecting linear?

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Yep, those are the channels you should be using.  Make sure they are set to differential.

And since you are getting a change in voltage with a change in pressure, it is now time to figure out the conversion.  The manual or spec sheet should have the conversion in it (pressure to mA most likely) which you can then use to make a DAQmx Scale inside of MAX.  You can then apply that scale to your channels and DAQmx Read will give you your pressure measurement.

[StuartWotherspoon]

I will dig out the manual.

What was confusing me was having 8 channels so what to select was getting me. If my resistor is in the right place as you say I just need the conversion to write the scale.

I feel a bit daft as it sounds a little simple now you've talked it through.