Two-Point Multiplier Only Calibration

Two-point multiplier only calibration uses a linear fit technique against two different known value conditions of the sensor’s measurement, but only the slope value (multiplier) is calculated and changed. The offset is unaffected by this calibration. The sensor is placed into the first condition, and the known value for that condition is provided to the datalogger program. One or more measurements in that first condition occur, and then the datalogger informs the user that the second known condition should be applied to the sensor. When that condition is applied, the second known value is provided to the datalogger, and the datalogger measures the second condition. After completing the measurement of the second point condition, a best fit of the two points is calculated, resulting in a slope value (m value or multiplier) with the offset assumed to be zero. Thus the simple form y=mx is a representation of the fit, where m is the new multiplier value.

To perform a two-point multiplier only calibration, use an argument of 3 (the number three) for the calibration type in the FieldCal() instruction of your CRBasic program. The Calibration Wizard can be used to calculate and apply the two different known conditions while the program is running in the datalogger.