National Instruments NI PXI-5422 Benutzerhandbuch

© National Instruments Corporation

Calibration consists of verifying the output accuracy of a device and 
correcting for any output error. Verification is measuring the performance 
of a device and comparing the results to the specifications of the device. 
NI calibrates every NI PXI-5422 at the factory. During the factory 
calibration process, the calibration constants are stored in an onboard 
EEPROM. These values are loaded from this EEPROM and used as needed 
by the NI PXI-5422. 

The NI PXI-5422 supports two types of calibration: self-calibration (or 
internal calibration) and external calibration. 

Self-calibration, also known as internal calibration, uses a software 
command and requires no external connections. Self-calibration improves 
output accuracy by compensating for variables, such as temperature and 
time, that may have changed since the last external calibration. 
Self-calibration retains the traceability of the external calibration.

External calibration is generally performed at either NI or a metrology lab. 
This 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 
instrument, a new calibration certificate can be issued.

The accuracy of electronic components drifts with time and temperature, 
which can affect output accuracy as a device ages. Calibration verifies 
that the NI PXI-5422 still meets its specified accuracy and NI standards. If 
adjustments are necessary, calibration makes the adjustments to restore 
the accuracy.

Self-calibration can be performed as necessary to compensate for 
environmental changes. 

Although you can use self-calibration repeatedly, self-calibrating the 

NI PXI-5422 more than a few times a day may cause excessive wear on the relays over 
time.