Error -201398 Occurred At Strain Gage Calibration

Updated Apr 13, 2022

Reported In

Hardware

  • C Series Strain/Bridge Input Device

Issue Details

I'm trying to take readings from a strain gage with my quarter-bridge strain gage module, but it won't calibrate. Instead, it gives an error of over 1000% and says: 

Error -201398 occurred at Strain Gage Calibration

Possible Reason(s):

Requested value is not supported for this property.


 

Solution

There are two potential causes for this error: 
  • This could be caused by the lead wire resistance. Quarter-bridge measurements are inherently sensitive to accuracy degradation due to the lead resistance of wiring from the sensor to the measurement device. The maximum usable lead wire resistance can vary. For example, with a 120 ohm strain gauge, on the NI-9235 it's around 18 ohms but may vary between devices and resistances. When using an NI 9235/9236 (the quarter-bridge modules), ensure that the resistance of the strain gage falls within the range listed in What Resistance Ranges Can be Used with the NI 9235 and NI 9236?
  • Another reason for this error is if you configured the incorrect Shunt Resistor value while configuring the calibration in the wizard. Check your module's manual to verify the correct value of the internal Shunt Resistor. 

Additional Information

Several things can affect the lead wire resistance. The material, length, and cross-sectional area of the wire will influence its resistance. If a strain gage has suddenly started giving this error, the lead wire resistance might have changed due to the temperature changing or the wire becoming more taught.

If a large lead wire resistance is expected, then a half-bridge or full-bridge completion module might be preferable.