National Instruments NI 4472, User Manual, Page: 42 / 73

© National Instruments Corporation 4-1 NI 4472 User Manual
4
Calibration
This chapter discusses the calibration procedures for your NI 4472. Your
NI 4472 comes with a calibration certificate. The certificate contains a
unique tracking number linking your device to the National Instruments
corporate databases where the traceability information is stored.
Calibration refers to the process of minimizing measurement and output
voltage errors by making small circuit adjustments. On the NI 4472
devices, these adjustments are made to the digital data coming from the
ADCs. If you are using the NI-DAQ device driver, the software includes
calibration functions for performing all of the steps in the calibration
process. 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 have very large offset and gain errors. The four levels
of calibration available are described in this chapter. The first level is the
fastest, easiest, and least accurate, whereas the last level is the slowest, most
complex, and most accurate.
Loading Calibration Constants
Your NI 4472 device is factory calibrated at approximately 25 °C to the
levels indicated in Appendix A,
Specifications . Before shipment, the
associated calibration constants—the values that were written to the
calibration circuitry to achieve calibration in the factory—are stored in the
onboard nonvolatile memory (EEPROM). Because the calibration circuits
have no memory, they do not retain calibration information when the
device is unpowered. Loading calibration constants refers to the process
of loading the calibration circuits with the values stored in the EEPROM.
NI-DAQ determines when this is necessary and does it automatically.