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Using the SCC-SG11 Shunt Calibration Module

Hardware: SCC>>Modules>>SCC-SG11

Problem: When I create a strain type global channel in MAX using a SCC-Series strain gage module, there's no option to perform calibration. How can I use the SCC-SG11 module to calibrate the SCC-SG0X or SCC-SG24 strain gage module?

Solution: The SCC-SG11 is a dual-channel shunt calibration module. It contains two shunt-calibration circuits, each consisting of a precision 301 k. resistor and a relay contact. The circuits are independent of each other, but the relay contacts are controlled together by one DAQ device digital output line. When the digital output is set to 1, the shunt-calibration circuits are enabled and the LED indicator on the SCC-SG11 is lit. When the digital output is set to 0, the circuits are disabled.

To perform shunt calibration using SCC-SG11:
  1. Perform null calibration of the system according to the procedure described in the "SCC-SG Series Strain Gage Modules User Guide".
  2. Install the SCC-SG11 into any digital input/output socket and connect it to the bridge configuration using additional wires. Refer to "Shunt Calibration Using the SCC-SG11" of the "SCC-SG Series Strain Gage Modules User Guide".
  3. Make an analog measurement from the strain gage module with the SG11 calibration circuits disabled.
  4. Make an analog measurement from the strain gage module with the SG11 calibration circuits enabled.
  5. The difference in the values measured in steps 3 and 4 will be the measured voltage difference (hereon known as DeltaVmeasured)
  6. Use the equation provided on page 18 of the manual to calculate the expected voltage difference (hereon known as DeltaVexpected)
  7. Finally, the correction factor (Fc) is calculated: Fc = DeltaVexpected/DeltaVmeasured.

The Fc value should be multiplied to all the measurements. This can be done by creating a scale or simply multiplying all measured values by Fc.

Related Links: User Manual: SCC-SG Series Strain Gage Module User Guide

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Report Date: 01/14/2005
Last Updated: 02/03/2006
Document ID: 3HDF8UNK

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