© National Instruments Corporation 9 NI USB-443x Calibration Procedure
3. Create and configure an AI voltage task on the NI USB-443x as shown in Table 7.
4. Acquire readings with the NI USB-443x.
5. Average all of the acquired samples. Record this value.
6. Repeat steps 1 through 5. In step 2, output 9 VDC instead of 0 VDC. Subtract the averaged value
measured for 0 VDC from the 9 VDC measurement.
7. Compare the calculated value to the DC coupled gain accuracy limits.
If verifying an NI USB-4431, compare the calculated value to the appropriate limits in Table 8. If
verifying an NI USB-4432, compare the calculated value to the appropriate limits in Table 9.
8. Repeat steps 1 through 5. In step 2, output –9 VDC instead of 9 VDC. Subtract the averaged value
measured for 0 VDC from the –9 VDC measurement.
Table 7. AI DC Coupled Gain Accuracy Verification Configuration for NI USB-443x
Configuration Value
Minimum value –10.0
Maximum value 10.0
Terminal configuration Pseudodifferential
Acquisition mode Finite number of samples
Rate 102400.0
Samples per channel 65,536
Coupling DC
Physical channel Dev_name/aix
*
*
Dev_name is the name shown for the NI USB-443x in MAX. x refers to the channel number.
Table 8. AI DC Coupled Gain Accuracy Limits for NI USB-4431
Calibrator Output
Amplitude (VDC)
Device Input Amplitude
(One Year Limits)
Min (V) Max (V)
9 8.9856 9.0144
–9 –9.0144 –8.9856
Table 9. AI DC Coupled Gain Accuracy Limits for NI USB-4432
Calibrator Output
Amplitude (VDC)
Device Input Amplitude
(One Year Limits)
Min (V) Max (V)
9 8.982 9.018
–9 –9.018 –8.982
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