©NationalInstruments Corporation 5-1 NI6013/6014 User Manual
5
Calibration
This chapter discusses the calibration procedures for the NI 6013/6014.
NI-DAQ 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. On th e NI 6013/6014,
these adjustments take the form of writing valuesto onbo ard calibration
DACs (CalDAC s).
Someform of device calibration is required for most applications. If you do
not calibrate the NI 6013/6014, the signals and measurements could have
verylarge 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

The NI 6013/6014 is factory calibrated before shipment at approximately
25°C to the levels 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
withthe values stored in the EEPROM. NI-DAQ determines when loadi ng
calibration constants is necessary and does it automatically. If you are not
using NI-DAQ, you must load these values yourself.
In the EEPROM,there is a user-modifiable calibration area in addition
to the permanent factory calibration area. The user-modifiablecalibration
area allowsyou to load the CalDACs with values either from the original
factorycalibration or from a calibrati ont hatyou subsequ ently performed.
Thismethod of calibration is not very accurate because it does not take into