cRIO-9215 issues

[JChookas]

I am using a cRIO-9215 with a clamp on current probe. The probe outputs 1mv/A (Maximum of 1.5V/1500A). I typically am measuring currents from 200-1000A but I am unable to get consistent data. I am receiving data using the DAQmx assistant in LabVIEW to receive data (once per second). If I am measuring a current that is 500A then LabVIEW will fluctuate anywhere between 450A-550A even though the current is actually very close to a constant 500A. I'm pretty sure that my current probe is functioning correctly because when I measure the output with a Fluke multi-meter I am receiving the correct voltage with no fluctuations. What am I doing wrong?

Thanks in advance.

[Tom Limerkens]

I assume that you are measuring current as a DC signal here.

Could it be that the current signal is not so 'constant' as you would expect?

Probably the multimeter is averaging the noise present on your signal.

Check the input signal of the module with an Oscilloscope, if you have one present, or I you haven't,

You could switch your multimeter to AC input, and that will give you a first idea how much 'noise'

there is present on your DC signal.

We use a CompactRIO/RT-FPGA chassis with a cRIO-9215 module to measure current. (4 V input eq. 15KA), and we use a

dedicated algorithm (at 40Khz sample rate) on the FPGA to get a decent, reliable Current signal.

Tom

*Edit: Typo*