About background calibration

The data logger uses an internal voltage reference to routinely self-calibrate and compensate for changes caused by changing operating temperatures and aging. Background calibration calibrates only the coefficients necessary to the running CRBasic program. These coefficients are reported in the Status table as CalVolts(), CalGain(), CalOffset(), and CalCurrent().

Background calibration will be disabled automatically when the scan rate is too fast for the background calibration measurements to occur in addition to the measurements in the program. The Calibrate() instruction can be used to override or disable background calibration. Disable background calibration when it interferes with execution of very fast programs and less accuracy can be tolerated. With background calibration disabled, measurement accuracy over the operational temperature range is specified as less accurate by a factor of 10. That is, over the extended temperature range of –55 °C to 85 °C, the accuracy specification of ±0.08 % of reading can degrade to ±0.8 % of reading with background calibration disabled. If the temperature of the data logger remains the same, there is little calibration drift when background calibration is disabled.