Appendix D
– 44 –
PCI-1721 User’s Manual
Advantech Co., Ltd.
www.advantech.com
D.1 VR Assignment
There is one variable resistor (VR1) on the PCI-1721 to adjust the
accurate reference voltage on the PCI-1721. We have provided a test
point (See J6 in Figure D-1) for you to check the reference voltage on
board. Before you start to calibrate A/D and D/A channels, please
adjust VR1 until the reference voltage on J6 has r10.0000 V.
Figure D-1 shows the locations of VR1 and J6.
Figure D-1: PCI-1721 VR assignment
D.2 D/A Calibration
You can select an on-board +5V or +10V internal reference voltage or
an external voltage as your analog output reference voltage. If you
use an external reference, connect the reference voltage within the
±10V range to the reference input of the D/A output channel you want
to calibrate. Then adjust the gain value, unipolar offset voltage, bipolar
offset voltage, respectively, of D/A channels 0 and 1 with the Calibra-
tion Command and Data register (BASE+26H).
Note:
✎
Using a precision voltmeter to calibrate the D/A outputs is
recommended.
