Barcode Reader User Manual

Chapter 3 Signal Connections

Quarter-Bridge Connection

In this configuration only one strain gauge is used. Bridge completion is provided by the internal

half-bridge completion reference as well as a quarter-bridge completion resistor. This quarter-

bridge completion resistor is equal in value to the external strain gauge element. Insert your

completion resistor in the appropriate sockets. Two lead wires connect the quarter-bridge strain

gauge to screw terminals +EXn and CHn+. If your strain gauge has three lead wires—two wires

at one end and one at the other end—connect the two wires sharing the same end of the strain

gauge at the CHn+ screw terminal, and connect the single wire end to the +EXn screw terminal.

Figure 3-3 shows this configuration, along with the appropriate quarter-bridge completion

resistor and half-bridge jumper placement.

Half-Bridge

Completion

Jumper

Half-Bridge

Completion

Reference

x10

+EX

-EX

Quarter Bridge

Quarter Bridge

Completion Resistor

(User Installed)

Figure 3-3. Quarter-Bridge Connection to the SC-2043-SG

Offset Nulling

Offset Nulling Adjustment

The SC-2043-SG has circuitry for offset nulling adjustment of Wheatstone bridges. The nulling

circuitry uses the excitation voltage as a reference and operates with full-bridge, half-bridge and

quarter-bridge strain gauge configurations. Each channel has its own nulling circuit, with a

trimming potentiometer to adjust the nulling voltage level, listed in Table 3-6.

Table 3-6. Offset Nulling Adjust Potentiometer and Corresponding Channel

Channel Trimming Potentiometer

0 R62

1 R50

2 R30

3 R14

4 R65

5 R51

6 R33

7 R17