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Appendix A Calibration
This chapter introduces the calibration process to minimize analog input measurement errors.
A�1 Calibration Constant
The PXIe-69852 is factory calibrated before shipment, with associated calibration constants written
to the onboard EEPROM. At system boot, the PXIe-69852 driver loads these calibration constants,
such that analog input path errors are minimized. JYTEK provides a software API for calibrating the
PXIe-69852.
The onboard EEPROM provides two banks for calibration constant storage. Bank 0, the default bank,
records the factory calibrated constants, providing written protection preventing erroneous
auto-calibration. Bank 1 is user-defined space, provided for storage of self-calibration constants.
Upon execution of auto-calibration, the calibration constants are recorded to Bank 1.
When PXIe-69852 boots, the driver accesses the calibration constants and is automatically set to
hardware. In the absence of user assignment, the driver loads constants stored in bank 0. If con-
stants from Bank 1 are to be loaded, the preferred bank can be designated as boot bank by software.
Following re-assignment of the bank, the driver will load the desired constants on system re- boot.
This setting is recorded to EEPROM and is retained until re- configuration.
A�2 Auto-Calibration
Because errors in measurement and outputs will vary with time and temperature, re-calibration
is recommended when the module is installed. Auto-calibration can measure and minimize errors
without external signal connections, reference voltages, or measurement devices.
The PXIe-69852 has an on-board calibration reference to ensure the accuracy of auto-calibration.
The reference voltage is mea- sured on the production line and recorded in the on-board EEPROM.
Before initializing auto-calibration, it is recommended to warm up the PXIe-69852 for at least 20
minutes and remove connected cables.
It is not necessary to manually factor delay into applications, as the PXIe-69852 driver
automatically adds the compensation time.
