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National Instruments Corporation
7
NI USB-443x Calibration Procedure
5.
If verifying an NI USB-4431, compare the averaged value to the limits in Table 3. If verifying an
NI USB-4432, compare the averaged value to the limits in Table 4.
6.
Repeat steps 1 through 5 for each analog input channel that you want to verify. Connect the BNC
shorting cap to the channel being verified in step 1. In step 2, replace
aix
in the physical channel
parameter with the channel being verified.
NI recommends that you verify each channel, but you can save time by verifying only the channels
used in your application.
7.
Repeat steps 1 through 6. In step 2, set the coupling parameter to AC.
Note
Skip the AC coupled portion of this procedure if both of the following apply:
•
Your device is hardware revision C or earlier.
•
You have never performed an analog input calibration adjustment according to this document.
AI AC Coupled Gain Accuracy Verification
Complete the following steps to verify AC coupled gain accuracy:
1.
Connect the output of the calibrator to the channel you want to verify on the device.
2.
Output a 1 kHz, 6.36 V
rms
AC signal from the calibrator.
Table 3.
AI Offset Limits for NI USB-4431
Coupling
Device Input Offset
(One Year Limits)
Min (mV)
Max (mV)
AC and DC
–1.3
1.3
Table 4.
AI Offset Limits for NI USB-4432
Coupling
Device Input Offset
(One Year Limits)
Min (mV)
Max (mV)
AC and DC
–3.2
3.2
