NI 5421/5441 Calibration Procedure
|
©
National
Instruments
|
47
•
vi
: The session handle returned from
niFgen_InitExtCal
•
channelName
:
"0"
•
attributeID
:
NIFGEN_ATTR_GAIN_DAC_VALUE
•
value
:
2300
p.
Call
niFgen_Commit
(niFgen Commit VI) to commit the attribute values to the
device using the following parameter:
•
vi
: The session handle returned from
niFgen_InitExtCal
q.
Wait 500 ms for the output to settle.
r.
Use the DMM to measure the voltage generated by the device. This measurement is
measurement 3
, which is used in step 12.
12. Call
niFgen_CalAdjustDirectPathGain
(niFgen Cal Adjust Direct Path Gain VI)
using the following parameters:
•
vi
: The session handle returned from
niFgen_InitExtCal
•
channelName
:
"0"
•
mainDACValues
: An array containing two elements—the two values (
32767
,
-
32767
) that you set on the main DAC in order
•
gainDACValues
: An array containing four elements—the four values (
1800
,
2600
,
1500
,
2300
) that you set on the gain DAC in order
•
measuredOutputs
: An array containing four elements—the four output voltages
(
measurement 0
,
measurement 1
,
measurement 2
,
measurement 3
) that
you measured in order
Adjusting the Oscillator Frequency
Adjusting the oscillator frequency involves generating a sine wave at a desired frequency and
then iteratively measuring the frequency, passing the measured value to NI-FGEN so that the
oscillator can be adjusted, and then remeasuring the resulting frequency. Repeat this process
until the difference between the desired and measured frequency falls within the desired
tolerance, which is 4.5 ppm. This adjustment ensures the frequency accuracy of the onboard
oscillator.
1.
Call
niFgen_InitializeOscillatorFrequencyCalibration
(niFgen Initialize
Oscillator Frequency Calibration VI) using the following parameter:
•
vi
: The session handle returned from
niFgen_InitExtCal
2.
Call
niFgen_SetAttributeViReal64
to set the sample rate (niFgen Set Sample Rate
VI) using the following parameters:
•
vi
: The session handle returned from
niFgen_InitExtCal
•
channelName
:
"0"
•
attributeID
:
NIFGEN_ATTR_ARB_SAMPLE_RATE
•
value
:
100000000
