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Chapter 5
Developing Your Application
Calibrating the NI PXI-4220
Calibrating the NI PXI-4220
NI PXI-4220 User Manual
•
PXI-4220 Supported Properties in the LabVIEW VI, Function, &
How-To Help.
•
Application Note 025: Field Wiring and Noise Considerations for
Analog Signals available at
the info code
rdfwn3
There are two types of calibration used to improve the accuracy of the
NI PXI-4220. Device calibration ensures the accuracy of the NI PXI-4220.
System calibration removes the offset and gain errors, two sources of
potential measurement errors.
The NI PXI-4220 is shipped with a calibration certificate and is calibrated
at the factory to the specifications described in Appendix A, Specifications.
Calibration constants are stored on the NI PXI-4220.
Internal Calibration Procedure
The NI PXI-4220 incorporates internal calibration paths that allow routing
channel inputs to ground or to an onboard high-precision reference voltage.
NI driver software disconnects the channel inputs from the front signal
connector and reconnects the inputs to ground or to an onboard reference
when performing an internal two-point calibration. The driver software
determines the correct adjustment factors for offset and gain error and
stores them as calibration constants. The driver software automatically uses
these adjustment factors to correctly scale each measurement. You need not
change any input connections for an internal calibration.
To obtain the highest level of accuracy, you should periodically perform an
internal calibration. You can self-calibrate the NI PXI-4220 within MAX.
To perform a self-calibration, complete the following steps:
1.
Double-click the Measurement & Automation Explorer icon on the
desktop.
2.
Display the list of devices and interfaces by clicking the + next to the
Devices and Interfaces icon.
3.
Display the list of NI-DAQmx devices by clicking the + next to
NI-DAQmx Devices icon.
4.
Right-click the NI PXI-4220 and select Self-Calibrate.
. Go to
ni.com
.
5-16
and enter
ni.com/info
ni.com
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