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-443
x
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-443
x
as shown
in Table 2.
3.
Acquire readings with the NI USB-443
x
.
4.
Average all of the acquired samples.
Table 2.
AI Offset Verification Configuration for NI USB-443
x
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/ai
x
*
*
Dev_name is the name shown for the NI USB-443
x
in MAX.
x
refers to the channel number.
