NI 5922 Calibration Procedure
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Introduction
The NI 5922 supports two types of calibration: self-calibration (or internal
calibration) and external calibration.
Self-Calibration
Self-calibration, also known as internal calibration, uses a software
command and requires no external connections. Self-calibration improves
measurement accuracy by compensating for variables such as temperature
that may have changed since the last external calibration. Self-calibration
retains the traceability of the external calibration.
External Calibration
External calibration is generally performed with a high-precision
oscilloscope calibrator at either NI or a metrology lab. The external
calibration procedure replaces all calibration constants in the EEPROM
and is equivalent to a factory calibration at NI. Because the external
calibration procedure changes all EEPROM constants, it invalidates the
original calibration certificate. If an external calibration is done with a
traceable signal generator source, a new calibration certificate can be
issued.
Calibration Intervals
Self-calibration can be performed as necessary to compensate for
environmental changes.
Caution
Although you can use self-calibration repeatedly, self-calibrating the NI 5922
more than a few times a day may cause excessive wear on the relays over time.
The measurement accuracy requirements of your application determine
how often you should externally calibrate the NI 5922. NI recommends
that you perform a complete external calibration at least once every
two years. You can shorten this interval based on the accuracy demands
of your application or the requirements of your processes. Refer to the
section for more information.
