Appendix A: Calibration; Complete Calibration - National Instruments PXI Manual

Appendix A: Calibration

External calibration involves verification and, if necessary, adjustment and reverification.
Adjustment is the process of measuring and compensating for device performance to improve
the measurement accuracy. Performing an adjustment updates the calibration date, effectively
resetting the calibration interval. The device is guaranteed to meet or exceed its published
specifications for the duration of the calibration interval. Verification is the process of testing
the device to ensure that the measurement accuracy is within certain specifications. Verification
can be used to ensure that the adjustment process was successful or to determine if the
adjustment process needs to be performed at all. During verification, you must compare the
measurement error to the limits given in each section.
This document provides two sets of test limits for most verification stages—the calibration test
limits and the published specifications. The calibration test limits are more restrictive than the
published specifications. If all of the measurement errors determined during verification fall
within the calibration test limits, the device is guaranteed to meet or exceed its published
specifications for a full calibration interval (two years). For this reason, you must verify against
the calibration test limits when performing verification after adjustment. If all of the
measurement errors determined during verification fall within the published specifications, but
not within the calibration test limits, the device is meeting its published specifications. While the
device does not necessarily remain within these specifications for an additional two years, it will
meet published specifications for the remainder of the current calibration interval. In this case,
you can perform an adjustment if you want to further improve the measurement accuracy or reset
the calibration interval. If some measurement errors determined during verification do not fall
within the published specifications, you must perform an adjustment to restore the device
operation to its published specifications.
The Complete Calibration section describes the recommended calibration procedure.

Complete Calibration

Perform a complete calibration to guarantee that the NI 5114 meets or exceeds its published
specifications for a two-year calibration interval. At the end of the complete calibration
procedure, verify that the measurement error falls within the calibration test limits. Figure 1
shows the programming flow for a complete calibration.
NI 5114 Calibration Procedure | © National Instruments | 41