National Instruments NI PXI-5422 用户手册

You can choose to skip the adjustment steps of the calibration procedure 
if the output error is within the calibration test limits or the published 
specifications during the first verification. If all of the output errors 
determined during the first verification fall within the calibration test 
limits, the device is guaranteed to meet or exceed its published 
specifications for a full calibration interval. In this case, you can update 
the calibration date, effectively resetting the calibration interval, without 
actually performing an adjustment. Refer to the 

section for more information.

If all of the output errors determined during the first verification fall within 
the published specifications, but not within the calibration test limits, 
adjustment is also optional. However, you cannot update the calibration 
date because the device will not necessarily operate within the published 
specifications for an additional two years.

Regardless of the results of the first verification, if you choose to perform an 

adjustment you must verify that the output error falls within the calibration test limits 
at the end of the calibration procedure. 

Figure 2 shows the programming flow for the optional calibration.