©NationalInstruments Corporation 5-1 6023E/6024E/6025EUser Manual
5
Calibration
This chapter discusses the calibration procedures for your device. If you
are usingthe NI-DAQ device driver, that software includes calibration
functions for performing all of the steps in the calibration process.
Calibration refers to theprocess of minimizing m easurementand output
voltageerrors by making small circuit adjustments. For these devices, these
adjustments take the form of writing valuesto onbo ard calibration DACs
(CalDACs).
Some form of device calibration is required for all but the most forgiving
applications. If you do not calibrate your device, your signals and
measurements could havevery large offset, gain, and linearity errors.
Threelevels of calibration are available toyou and described in this chapter.
The firstlevel is the fastest, easiest, and least accurate, whereas the last
levelis the slowest, most difficult, and most accurate.

Loading Calibration Constants

Yourdevice is factory calibrated before shipment at approximately 25 °C
to thel evels indicated in Appendix A, Specifications. The associated
calibration constants—the values that were written to the CalDACs to
achievecalibration i n thefactory—are sto red in the onboard nonvolatile
memory (EEPROM). Because the CalDACs have no memory capability,
they do not retain calibration information when the device is unpowered.
Loadingcalibration constants refers to the process of loading the CalDACs
with the values stored in the EEPROM.N I-DAQ softwaredetermines
when this isnecessary and does it automatically. If you are not using
NI-DAQ, youmust load these values yourself.
In theEEPROM there is a user-modifiable calibration area in addition to
the permanentfactory calibration area. This means that you can load the
CalDACswith values either from the original factory calibration or from a
calibration that you subsequently performed.