NI USB-443x Calibration Procedure
16
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Analog Output Adjustment for the NI USB-4431 Device
Complete the following steps to adjust the analog output of the NI USB-4431 device.
1.
Connect channel AO 0 on the device to the multimeter.
2.
Initialize the AO calibration using the DAQmx Initialize External Calibration VI as shown below.
3.
Create and configure an AO voltage task on the NI USB-4431 as shown in Table 17.
4.
Create an array of length 96,000. Set every element in the array to a value of 2.0. Write the array
to the AO task.
5.
Start the AO task. The AO channel will output 2.0 V as long as the task is running because
regeneration mode is enabled and the task is configured to generate samples continuously.
6.
Wait 100 ms. This compensates for the filter delay of the analog output channel.
7.
Measure the DC voltage of channel AO 0 on the device using the multimeter. Record this value as
actualHighVoltage
.
8.
Stop and clear the AO task.
9.
Repeat steps 3 through 8. In step 4, set every element in the array to a value of –2.0 instead of 2.0.
In step 7, record the measured value as
actualLowVoltage
.
LabVIEW Block Diagram
NI-DAQmx Function Call
Call
DAQmxInitExtCal
with the following
parameters:
deviceName
:
Dev_name
password
:
NI
calHandle
:
&myCalHandle
Table 17.
Analog Output Adjustment 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.
