Error concerning current measurement

[Squinn21]

I am trying to measure a voltage differential from a device (Magnehelic) which produces the 4-20mA output. I am using a DAQcard-6024. In the configuration window, I set the max and min input range with a 6 and 0. I have custom scaling with a slope of .375 and a y-intercept of -1.5. I keep receiving an error message saying that my max and min values don't fall within the appropriate range. It says the appropriate range is between -1.49... and -1.51...  Any ideas on what could be causing this problem?

[Kristen_K.]

Hi Squinn21,

The max in min values include the custom scale, so calculate what the new_min would be using the custom scale and the raw_min and set that to be the minimum of the range. Then do the same for the max.  Your range should be good to go then!

Kristen H.

Message Edited by Kristen H. on 08-19-2009 04:02 PM

[Squinn21]

I have done so already. Do you have any other ideas? Could the problem be caused by bad wiring?

[AnalogKid2DigitalMan]

Squinn21:

Regardless of scaling errors, I believe the 6024 can only read voltage inputs, not current. You would need to place a 250 ohm precision resistor across the DAQ input terminals to convert the 4-20mA into a 1-5V siganl the DAQ can read.

-AK2DM