NI USB-443x Calibration Procedure 6 ni.com
Verification
This section provides instructions for verifying the NI USB-443x Specifications for gain, offset, and
frequency accuracy. By completing this procedure, you can see how device accuracy has drifted over
time, which helps you determine the appropriate calibration interval for your application.
Note Limits in Tables 3, 4, 6, 8, 9, 11, 13, and 15 are for the specified calibration sample rates and
temperatures, and are based on the March 2011 edition of the NI USB-443x Specifications. For more
general specifications, refer to the most recent NI USB-443x Specifications online at
ni.com/
manuals
. If a more recent edition of the specifications is available, recalculate the limits based upon
the latest specifications.
Analog Input Performance Verification
This section verifies the analog input (AI) performance of NI USB-443x devices. Refer to the
NI USB-443x Specifications for the number of channels and performance specifications.
AI Offset Verification
Note Skip the AC coupled portion of this procedure if both of the following apply:
• Your device is hardware revision C or earlier.
• You have never performed an analog input calibration adjustment according to this document.
Complete the following steps to verify the AI offset:
1. Connect a BNC shorting cap to the channel you want to verify on the device.
2. Using Figure 2 as a guide, create and configure an AI voltage task on the NI USB-443x as shown
in Table 2.
3. Acquire readings with the NI USB-443x.
4. Average all of the acquired samples.
Table 2. AI Offset 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 102400.0
Samples per channel 65,536
Coupling DC
Physical channel Dev_name/aix
*
*
Dev_name is the name shown for the NI USB-443x in MAX. x refers to the channel number.
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