NI USB-443x Calibration Procedure 12 ni.com
8. Repeat steps 1 through 7. In step 3, set every element in the array to a value of –3.15 instead of
3.15. Compare the result to the limits in Table 13.
Timebase Frequency Accuracy Verification
This section describes the process used to verify the frequency accuracy of the timebase on
NI USB-443x devices. All analog input and output channels on a single device use the same timebase
circuitry. Therefore, you only need to verify the timebase accuracy on one channel.
Complete the following steps to verify the timebase accuracy:
1. Connect the function generator to the channel being verified on the device.
2. Configure the function generator to generate a 10 kHz sine wave with an amplitude of 9 V
pk
and
no DC offset.
3. Create and configure an AI voltage task on the NI USB-443x as shown in Table 14.
4. Acquire readings with the NI USB-443x.
Table 13. AO Gain Limits for NI USB-4431
Device Output Amplitude
(VDC)
Device Input Amplitude
(One Year Limits)
Min (V) Max (V)
3.15 3.1437 3.1563
–3.15 –3.1563 –3.1437
Table 14. Timebase Frequency 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 40000.0
Samples per channel
*
2,560,000
Coupling DC
Physical channel Dev_name/aix
†
*
The read timeout must be greater than 64 seconds.
†
Dev_name is the name shown for the NI USB-443x in MAX. x refers to the channel number.
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