VR Assignment. HP (Hewlett-Packard) NuDAQ PCI-9111HR, PCI-9111DG/HR

6.2 VR Assignment

There are five variable resistors (VR) on the PCI-9111 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

VR2

VR3

VR4

VR5

D/A full scale adjustment

D/A offset adjustment

A/D offset adjustment

A/D full scale adjustment

A/D programmable amplifier offset adjustment

Table 6.1 Functions of VRs

6.3 A/D Adjustment

1. Set the analog gain = 1 and channel number #0 by software.

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 VR5 to obtain a value as close as possible to 0V.

3. Applied a +10V reference input signal to A/D channel 0, and trim the

VR4 to obtain reading between 2046~2047(9111DG) or

32766~32767(9111HR).

4. Short the A/D channel 0 to ground, and trim the VR3 to obtain reading flickers between 0~1.

5. Repeat step 3 and step 4, adjust VR4 and VR3.

66 • Calibration