National Instruments NI PXI-5422

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.