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Calibration
6.2 VR Assignment
There are five variable resistors (VR) on the PCI-9112 board to allow you
making accurate adjustment on A/D and D/A channels. The function of
each VR is specified as Table 6.1.
VR1 A/D bipolar offset adjustment
VR2 A/D full scale adjustment
VR3 D/A channel 1 full scale adjustment
VR4 D/A channel 2 full scale adjustment
VR5 A/D unipolar offset adjustment
VR6 D/A reference voltage adjustment
VR7 A/D programmable amplifier offset adjustment
Table 6.1 Function of VRs
6.3 A/D Adjustment
6.3.1 Bipolar Calibration
1. Set the analog input range as : +/- 5V, i.e. the gain = 1 and input
mode = Bipolar.
2. Short the A/D channel 0 (pin 1 of CN3) to ground (GND), and connect
the TP1 (+) and TP2 (-) with your DVM. Trim the variable resister VR7 to
obtain a value as close as possible to 0V.
3. Apply a +5V input signal to A/D channel 0, and trim the VR2 to obtain
reading between 4094~4095.
4. Apply a +0V input signal to A/D channel 0, and trim the VR1 to obtain
reading flickers between 2048~2049.
5. Repeat step 3 and step 4, adjust VR2 and VR1.
6.3.2 Unipolar Calibration
1. Set the analog input range as : 0 ~ 10 V, i.e. the gain = 1 and input
mode = Unipolar.
2. Short the A/D channel 0 (pin 1 of CN3) to ground (GND) and connect
TP1 (+) and TP2 (-) with your DVM. Trim the VR5 to -5V reading in the
DVM.