NI DAQ 6052E, Руководство пользователя

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Chapter 5 Calibration
NI 6052E User Manual 5-2 ni.com
This method of calibration is somewhat inaccurate because it does not
account for device measurement and output voltage errors, which can vary
with time and temperature. You should self-calibrate when the device is
installed in the environment in which it will be used.
Self-Calibration
The device can measure and correct for almost all of its calibration-related
errors without any external signal connections. NI software provides a
self-calibration method, which generally takes less than a minute and is
the preferred method of ensuring accuracy in your application. Initiate
self-calibration to minimize the effects of any offset, gain, and linearity
drifts, particularly those due to the device not being fully warmed up.
Immediately after self-calibration, the only significant residual calibration
error could be gain error due to time or temperature drift of the onboard
voltage reference. This error is addressed by external calibration, which is
discussed in the following section. If you are interested primarily in relative
measurements, you can ignore a small amount of gain error, and
self-calibration is sufficient.
External Calibration
The device has an onboard calibration reference to ensure the accuracy of
self-calibration. Its specifications are listed in Appendix A,
Specifications .
The reference voltage is measured at the factory and stored in the EEPROM
for subsequent self-calibrations. This voltage is stable enough for most
applications, but if you are using the device at an extreme temperature or if
the onboard reference has not been measured for a year or more, you can
externally calibrate the device.
External calibration is the process of calibrating the device with a
known external reference rather than relying on the onboard reference.
Redetermining the value of the onboard reference is part of this process,
and you can save the results in the EEPROM, so you will not need to
externally calibrate often. You can externally calibrate the device by calling
the NI-DAQ calibration function.
To externally calibrate the device, be sure to use a very accurate external
reference. The reference should be several times more accurate than the
device itself. For example, to calibrate a 16-bit device, the external
reference should be at least ±0.001% (±10 ppm) accurate.