9203 Current Readings

[McFadden]

Hi There,

I have a system using a compact rio, in which we are using a couple 9203 analog input cards.  We have configured the cards to be unipolar (0-20mA) inputs.  To the inputs, we are connecting pressure transducers that provide a 4-20mA signal.

We have set the "Raw Full Scale" to 20, and the "Raw Zero Scale" to 4, in the properties for each of the input channels.  When we put a digital multimeter in series with the current loop, we can read an amperage of 4mA (there is currently no pressure on our lines).

So here is the problem, when we open the system manager in LabVIEW and look at the values returned by the 9203 cards, we see pressure values corresponding to 0mA, or open loop (i.e. they are negative PSI values, which I plugged into the appropriate linear equation for each input).

Any ideas as to what could be wrong?

Cheers.

[Hueter]

a few questions:

Which cRIO are you using?

What version of LabVIEW are you using?

What version of NI RIo are you using?

Other than the scaling, is it reading the signals correctly?

[McFadden]

Thanks for the response Hueter.

We have figured out the problem. It was a simple scaling issue.  Even though everything seems to be specified in mA for the 9203 card, the "Raw Full Scale" and "Raw Zero Scale" values must be entered in Amps (0.004 and 0.02 in comparison to 4 and 20, which we had).

Cheers

[Hueter]

Thanks for letting us know!