ADLINK PXI-2022 - Manual (Page 58)

50 Calibration
5.2 Auto-calibration
By using the auto-calibration feature of the PXI-2020/2022, the
calibration software can measure and correct almost all the cali-
bration errors without any external signal connections, reference
voltages, or measurement devices.
The PXI-2020/2022 has an on-board calibration reference to
ensure the accuracy of auto-calibration. The reference voltage is
measured at the factory and adjusted through a digital potentiome-
ter by using an ultra-precision calibrator. The impedance of the
digital potentiometer is memorized after this adjustment. It is not
recommended for users to adjust the on-board calibration refer-
ence except when an ultra-precision calibrator is available.
Note:
1. Before auto-calibration procedure starts, it is recom-
mended to warn up the card for at least 15 minutes.
2. Please remove the cable before an auto-calibration pro-
cedure is initiated because the DA outputs would be
changed in the process of calibration.
5.3 Saving Calibration Constants
After an auto-calibration is completed, users can save the new cal-
ibration constants into one of the three user-modifiable banks in
the EEPROM. The date and the temperature when you ran the
auto-calibration will be saved accompanied with the calibration
constants. This means users can store three sets of calibration
constants according to three different environments and reload the
calibration constants later.