© National Instruments Corporation 11 NI USB-443x Calibration Procedure
7. Compare the measured voltage value to the AO offset limits in Table 11.
8. Stop and clear the AO task.
AO Gain Verification for the NI USB-4431 Device
Complete the following steps to verify AO gain accuracy:
1. Connect channel AO 0 on the device to the input of the multimeter.
2. Create and configure an AO voltage task on the NI USB-4431 as shown in Table 12.
3. Create an array of length 96,000. Set every element in the array to a value of 3.15. Write the array
to the AO task.
4. Start the AO task. The AO channel will output 3.15 V as long as the task is running, because
regeneration mode is enabled and the task is configured to generate samples continuously.
5. Wait 100 ms. This compensates for the filter delay of the analog output channel.
6. Measure the DC voltage of the analog output channel using the multimeter in the appropriate range
for a 3.5 V amplitude. Subtract the value measured in step 6 of the AO Offset Verification for the
NI USB-4431 Device procedure, and compare this value to the limits in Table 13.
7. Stop and clear the AO task.
Table 11. AO Offset Limits for NI USB-4431
Device Output Offset
(One Year Limits)
Min (mV) Max (mV)
–1.3 1.3
Table 12. AO Gain Verification Configuration for NI USB-4431
Configuration Value
Minimum value –3.5
Maximum value 3.5
Terminal configuration Pseudodifferential
Acquisition mode Continuous samples
Rate 96000.0
Samples per channel 96,000
Regeneration mode Allow regeneration
Physical channel Dev_name/ao0
*
*
Dev_name is the name shown for the NI USB-4431 in MAX.
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