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© National Instruments Corporation 33 NI PXI-5422 Calibration Procedure
1. Call niFgen_InitExtCal (niFgen Init Ext Cal VI) to open an
NI-FGEN external calibration session using the following parameters:
• resourceName: The name of the device you want to calibrate.
This name can be found under Devices and Interfaces in MAX.
• password: The password required to open an external
calibration session. If this password has not been changed
since manufacturing, the password is
NI.
• vi: A pointer to a ViSession. The variable passed by reference
through this parameter receives the value that identifies the
external calibration session created by this function. This value
acts as the session handle and is passed as the first parameter to
all subsequent NI-FGEN functions.
2. Call
niFgen_CloseExtCal (niFgen Close Ext Cal VI) using the
following parameters:
• vi: The session handle returned from
niFgen_InitExtCal
• action:
NIFGEN_VAL_EXT_CAL_COMMIT
The external calibration procedure adjusts the analog output, the oscillator
frequency, and the calibration ADC. Analog output adjustment
characterizes the DC gains and the offsets of the analog path to ensure
the analog output voltage accuracy. Adjusting the oscillator frequency
adjusts the onboard oscillator to ensure frequency accuracy. Calibration
ADC adjustment characterizes the onboard ADC gain and offset so that
self-calibration results in an accurately calibrated device.
You cannot perform an external calibration using a standard NI-FGEN
session. You must create an external calibration session using
niFgen_InitExtCal (niFgen Init Ext Cal VI). An external calibration
session allows you to use NI-FGEN functions and attributes that are
specifically for external calibration, while still allowing you to use all
the standard NI-FGEN functions and attributes with the external calibration
session.
Along with the standard NI-FGEN attributes, the external calibration
session uses a set of calibration constants that are determined during the
calibration procedure and stored in the device onboard memory when
the session is closed. NI-FGEN uses these calibration constants during
a standard NI-FGEN session to ensure that the device operates within its
specifications.
You must close an external calibration session by using
niFgen_CloseExtCal (niFgen Close Ext Cal VI), as shown in Figure 4.