Appendix A: Calibration Options - National Instruments NI PXI-5122 Calibration Procedure

Appendix A: Calibration Options

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. However,
the device will not necessarily remain within these specifications for an additional two years.
The device 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. The
Optional Calibration section describes alternative procedures that allow you to skip adjustment
if the device already meets its calibration test limits or published specifications.
42 | ni.com | NI 5122/5124/5142 Calibration Procedure