Manual PCI-DA12-8/16
26
Chapter 8: Calibration
Periodic calibration of these cards is recommended if they are used in extreme environmental conditions.
The card uses very stable components but high-low temperature cycles might result in slight analog
output errors.
This card is calibrated by software using the following formula:
Y= (4096 -a - b)/4096) * X + b
To calibrate the card, run the calibration program and follow the screen prompts. No attempt at calibration
should be made in noisy locations or with a noisy calibration setup.
The calibration program stores various data to the card to facilitate calibrating the data output in a run-
time environment. The data collected during calibration is stored in an EEPROM located at the second of
the I/O base addresses assigned to the device (BaseAddresses[3] in the PCI_COMMON_CONFIG
structure). The EEPROM contains two values per channel per range. The ZERO (or OFFSET) and the
SPAN calibration constants are stored (a and b from the equation above) for each channel at each
possible range (0-6). These constants are used during normal operation to calibrate the output data in
real-time. Refer to the samples provided on disk for an example of using this data.
In addition to 'a' and 'b' as shown above, the EEPROM contains a table of ranges assigned to each
channel. Starting at Base+F0, 16 base addresses contain one byte each, from 0-6, indicating the voltage
output range assigned to that channel. It is important to use the calibration program at least once if the
default range (+/- 10V) is changed on any channel, to allow this table of data to be reconfigured. If this
data is incorrect, calibration is not guaranteed.
Word Address
Range
Offset
(‘b’ in formula)
Span
(‘a’ in formula)
Base + 00h
to
Base + 1Eh
0 to +5 V.
DAC 0
to
DAC 15
DAC 0
to
DAC 15
Base + 20h
to
Base + 3Eh
0 to +2.5 V.
DAC 0
to
DAC 15
DAC 0
to
DAC 15
Base + 40h
to
Base + 5Eh
0 to +10 V.
DAC 0
to
DAC 15
DAC 0
to
DAC 15
Base + 60h
to
Base + 7Eh
-5 V to +5 V.
DAC 0
to
DAC 15
DAC 0
to
DAC 15
Base + 80h
to
Base + 9Eh
-2.5 V to 2.5 V.
DAC 0
to
DAC 15
DAC 0
to
DAC 15
Base + A0h
to
Base + BEh
-10 V to 10 V.
DAC 0
to
DAC 15
DAC 0
to
DAC 15
Base + C0h
to
Base + DEh
4 to 20 mA.
DAC 0
to
DAC 15
DAC 0
to
DAC 15
