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Chapter 2 Function Reference — Calibrate_E_Series
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National Instruments Corporation 2-59 NI-DAQ FRM for PC Compatibles
setOfCalConst selects the set of calibration constants to be used by NI-DAQ. These
calibration constants reside in the onboard EEPROM or are maintained by NI-DAQ.
Range:
ND_FACTORY_EEPROM_AREA: Factory calibration area of the EEPROM. You cannot
modify this area, so you can set setOfCalConst to
ND_FACTORY_EEPROM_AREA only when calOP is set
to
ND_SET_DEFAULT_LOAD_AREA.
ND_NI_DAQ_SW_AREA: NI-DAQ maintains calibration constants internally; no
writing into the EEPROM occurs. You cannot use this
setting when calOP is set to
ND_SET_DEFAULT_LOAD_AREA. You can use this
setting to calibrate your device repeatedly during your
program, and you do not want to store the calibration
constants in the EEPROM.
ND_USER_EEPROM_AREA: For the user calibration area of the EEPROM. If calOP
is set to
ND_SELF_CALIBRATE or
ND_EXTERNAL_CALIBRATE, the new calibration
constants is written into this area, and this area becomes
the new default load area. You can use this setting to run
several NI-DAQ applications during one measurement
session conducted at same temperature, and you do not
want to recalibrate your device in each application.
calRefVolts is the value of the DC calibration voltage connected to analog input channel 0
when calOP is
ND_EXTERNAL_CALIBRATE. This parameter is ignored when calOP is
ND_SET_DEFAULT_LOAD_AREA or ND_SELF_CALIBRATE.
Range:
12-bit E Series devices: +6.0 to +10.0 V
16-bit E Series devices: +6.0 to +9.999 V
Using This Function
Your device contains calibration D/A converters (calDACs) that are used for fine-tuning the
analog circuitry. The calDACs must be programmed (loaded) with certain numbers called
calibration constants. Those constants are stored in non-volatile memory (EEPROM) on your
device or are maintained by NI-DAQ. To achieve specification accuracy, you should
perform an internal calibration of your device just before a measurement session but after
your computer and the device have been powered on and allowed to warm up for at least
15 minutes. Frequent calibration produces the most stable and repeatable measurement
performance. The device is not affected negatively if you recalibrate it as often as you want.
Two sets of calibration constants can reside in two load areas inside the EEPROM; one set
is programmed at the factory, and the other is left for the user. One load area in the EEPROM
corresponds to one set of constants. The load area NI-DAQ uses for loading calDACs with
calibration constants is called the default load area. When you get the device from the factory,