©
National Instruments Corporation
29
NI 5421/5441 Calibration Procedure
Adjusting the NI 5421/5441
If the NI 5421/5441 successfully passes all verification within the
calibration test limits, adjustment is recommended, but not required, to
guarantee its published specifications for the next two years. If the
NI 5421/5441 is not within the calibration test limits for each verification
procedure, perform the adjustment procedure to improve the accuracy of
the NI 5421/5441. Refer to the
section to
determine which procedures to perform.
An adjustment is required only once every two years. The adjustment
procedure automatically updates the calibration date and temperature in
the EEPROM of the signal generator.
If the NI 5421/5441 passed verification within the calibration test limits and
you do not want to do an adjustment, you can update the calibration date
and onboard calibration temperature without making any adjustments by
completing the following steps:
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.
