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National Instruments Corporation
9
NI USB-443x Calibration Procedure
3.
Create and configure an AI voltage task on the NI USB-443
x
as shown in Table 7.
4.
Acquire readings with the NI USB-443
x
.
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-443
x
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/ai
x
*
*
Dev_name is the name shown for the NI USB-443
x
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
