ADLINK PXIe-9848 - Manual (Page 39)

Calibration 29
PXIe-9848
4 Calibration
This chapter introduces the calibration process to minimize analog
input measurement errors and analog output errors.
4.1 Calibration Constant
The PXIe-9848 is factory calibrated before shipment, with associ-
ated calibration constants written to the onboard EEPROM. At
system boot, the PXIe-9848 driver loads these calibration con-
stants, such that analog input path and analog output circuit errors
are minimized. ADLINK provides a software API for calibrating the
PXIe-9848.
The onboard EEPROM provides three banks for calibration con-
stant storage. Bank 0, the default bank, records the factory cali-
brated constants, providing written protection preventing
erroneous auto-calibration. Bank 1 is user-defined space, pro-
vided for storage of self-calibration constants. Upon execution of
auto-calibration, the calibration constants are recorded to bank 1.
When PXIe-9848 boots, the driver accesses the calibration con-
stants and is automatically set to hardware. The driver loads con-
stants stored in bank 1 by default. Constants from bank 0 can be
loaded, with the preferred bank designated as boot bank by soft-
ware. 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.
4.2 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 mea-
surement devices.
The PXIe-9848 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.