Accurate Voltage Measurements with SCXI-1520

[Venkat Narsimha]

Iam using a SCXI-1520 for Voltage acquisitions in the range of -10 to 10V. The error deviation was as high as 600mV. I have tried configuring SCXI-1520 as "AI Voltage with Excitation" and also as a normal Strain Guage module, in both the cases I have configured the Bridge as Full Bridge, Iam not using any of the Caliburations or Offset Nulling VI's.In both the cases the Excitation I want to generate is being generated by the card Accurately but Iam not able to measure the voltages. When SCXI-1520 is configured for Strain Guage configuration in MAX also Iam not able to measure the Voltage with in millivolts range.
Please help me out on this.

[David L.]

Hi RVNR,

Are you wanting to read strain or voltage? If you are doing voltage readings, please see KB 2AJE1KJW.

For strain, lets first make sure that everything is hooked up OK, and we are getting correct strain readings in Measurement and Automation Explorer (MAX) (Start >> Programs >> National Instruments >> Meas.. ) before attempt things in LabVIEW. Since the SCXI-1520 is a strain gauge module, let’s create a strain DAQmx task in MAX, and set it up with the appropriate required setup values. After the setup is finished, click the “Test” button and see if you are taking correct readings. If calibration is needed, you can use the calibration tab and the instructions will guide you through this process.

If you get any errors that you cannot find information about, please list them in detail so I can help you out. Also, what values are you reading and what are you expecting?