National Instruments SC-2040 Input Mode Selection

Chapter 2 Configuration and Installation
© National Instruments Corporation 2-7 SC-2040 User Manual
To close a switch, push down the number side. Closing switch A selects a gain of 500. Closing
switch B selects a gain of 200. Closing switch C selects a gain of 100. Closing switch D selects
a gain of 10. Opening all the switches selects a gain of 1. You can select other gains by closing
more than one switch, as shown in Table 2-7.
Table 2-7. Switch Settings for Gain Selection
Desired Gain Close Switches
1 None
10 D
100 C
200 B
300 B and C
500 A
600 A and C
700 A and B
800 A, B, and C
Input Mode Selection
Jumpers W2 through W9 select the input mode for each channel on the SC-2040. Position A-B
leaves the negative input of the instrumentation amplifier connected only to the front connector.
This is the factory-default setting. Position B-C connects the negative input of the
instrumentation amplifier to the board analog ground through a 100 kΩ resistor. This setting is
useful for keeping floating, or nonground-referenced, sources from saturating the instrumentation
amplifier. Table 2-8 shows the input mode jumper and channel selections.
Table 2-8. Input Mode Selection Jumpers
Channel Use Jumper
0W2
1W3
2W4
3W5
4W6
5W7
6W8
7W9