National Instruments NI 4495, Процедура калибровки, Страница: 10 / 22

NI 449
x
Calibration Procedure | © National Instruments | 9
3. Create and configure an AI voltage task on the NI 4492/4496/4497/4498/4499 as shown in
Table 9.
4. If verifying an NI 4492/4497/4499 and the coupling changes from DC to AC, commit the
configuration using the DAQmx Control Task VI and wait 5 seconds for the input to settle.
5. Start the task.
6. Acquire readings with the NI 4492/4496/4497/4498/4499.
7. Stop and clear the task.
8. Calculate the rms amplitude of the acquired fundamental harmonic. Compare this
amplitude to the appropriate voltage limits in Table 7 for the NI 4496/4498 or Table 8 for
the NI 4492/4497/4499. The calculated amplitude is used to verify the AC coupled gain
accuracy of channel AI 0 at the 0 dB gain setting, at the 204.8 kS/s sample rate.
9. If verifying an NI 4496/4498, repeat steps 2 through 8 for each gain setting that your device
supports. Refer to Table 10 for the gain settings supported by NI 449x devices. In step 2,
change the output of the calibrator based on the gain setting that is being verified. Table 7
lists the amplitude and frequency to use for each gain setting. When performing step 3,
adjust the gain parameter appropriately.
Table 9. NI 4492/4496/4497/4498/4499 AI AC Coupled Gain Accuracy
Verification Configuration
Configuration Value
Minimum value –10.0
Maximum value 10.0
Terminal configuration Pseudodifferential
Acquisition mode Finite number of samples
Rate 204,800.0
Samples per channel 102,400
Gain 0 (dB)
Physical channel Dev_name/ai0*
Coupling AC
*
Dev_name is the name shown for the NI 449x in MAX.