21
Appendix A Calibration
This chapter introduces the calibration process to minimize analog input measurement
errors.
A�1 Calibration Constant
The PXIe-69529 is factory calibrated before shipment, with associated calibration constants
written to the onboard EEPROM. At system boot, the PXIe-69529 driver loads these
calibration constants, such that analog input path errors are minimized. JYTEK provides a
software API for calibrating the PXIe-69529.
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-69529 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 constants 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 reboot. This setting is recorded to EEPROM and is retained
until reconfiguration.
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-69529 has an on-board calibration reference to ensure the accuracy of auto-
calibration. The reference voltage is measured on the production line and recorded in the
on-board EEPROM.
Before initializing auto-calibration, it is recommended to warm up the PXIe-69529 for at
least 20 minutes and remove connected cables.
It is not necessary to manually factor delay into applications, as the PXIe-69529
driver automatically adds the compensation time.
