User`s guide

Calibration • 91
6.2 VR Assignment
There are five variable resistors (VR) on the PCI-9111 board to allow you
making accurate adjustment of the A/D and D/A channels. The function of
each VR is specified in Table 6 below.
VR1 D/A full scale adjustment
VR2 D/A offset adjustment
VR3 A/D offset adjustment
VR4 A/D full scale adjustment
VR5 A/D programmable amplifier offset adjustment
Table 6: Functions of VRs
6.3 A/D Adjustment
1. Set the analog gain = 1 and channel number #0 using the software
package.
2. Short the A/D channel 0 (pin 1 of CN3) to ground (GND), and connect
TP1(+) and TP2(-) to the DVM. Trim variable resister VR5 to obtain a
value as close as possible to 0V.
3. Applied a +10V reference input signal to the A/D channel 0, and trim VR4
to obtain reading between 2046~2047 (9111DG) or 32766~32767
(9111HR).
4. Short the A/D channel 0 to ground, and trim VR3 to obtain a reading that
toggles between 0~1.
5. Repeat steps 3 and 4, until the reading as indicated without having to do
any further adjustments to VR3 and VR4.