Incorrect Load Cell Readings with a Linear Scale

Updated Dec 11, 2018

Reported In

Hardware

  • NI-9237

Software

  • Measurement & Automation Explorer (MAX)

Driver

  • NI-DAQmx

Issue Details

I have a load cell that outputs mV and applied a linear scale to display pounds as the final unit.  When I verify my readings with known forces, the values appear to be incorrect. What can I do to allow the values to scale correctly? 

Solution

Create a custom table scale using the Certificate of Calibration provided with your load cell or by using a calibrator to generate them.  The Certificate of Calibration is a list of the force and corresponding output voltage recorded during the calibration. This will be specific to each load cell that is being used. The custom table scale will give the most accurate scaling for each individual load cell. 

For example, if  the Certificate of Calibration lists the load as -5 lbs and the mV/V as -1.95, then select Add and enter -0.00195 for Pre-Scaled and -5 for Scaled.

You can set up a custom table scale in MAX by right-clicking Scales under the Configuration window, then select New Scale»NI-DAQmx Scale»Table.


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