National Instruments 1128 用户手册

Figure 2-7.  4-Wire Wiring Diagram

On power up, the AB0 and AB2 switches are open, disconnecting the 
SCXI-1127/1128 from the high-voltage bus. If you are using this module 
with a high-voltage backplane, you need to close the AB0 and AB2 
switches to connect the EXCITATION and SENSE commons to the HVAB 
backplane.

Figure 2-7 shows an example of a 4-wire configuration using the 
SCXI-1331 terminal block. The diagram shows the 4-wire terminal block 
connections for channels 1 and 12. Resistance is measured on both 
channels. Each channel has excitation pair positive and negative terminals 
labeled 1A and 12A and SENSE terminals labeled 1B and 12B respectively.

R1 is excited through the 12A positive and negative screw terminals and the 
voltage drop across the resistor is measured through the 12B positive and 
negative screw terminals. R2 is excited through the 1A positive and 

SCXI-1127

R

2

–

–

+

+

R

2

Sense Output

6A ± Excitation for Four-Wire Channel 6

6B ± Sense for Four-Wire Channel 6

–

+

–

+

Excitation Input

Iex

Iex