©
National Instruments Corporation
3
SCXI-1317 Terminal Block Installation Guide
Quarter-Bridge 2- and 3-Wire Strain-Gauge Circuits
Note
Refer to the
Read Me First: Safety and Radio-Frequency Interference
document
before removing equipment covers or connecting or disconnecting any signal wires.
This section provides information about making quarter-bridge signal
connections using either a 2- or 3-wire strain gauge. Figures 1 and 2 show
the circuit wiring diagrams. If the transducer is shielded, connect the shield
to the GND connection on the SCXI-1317 terminal block.
Figure 1.
Quarter-Bridge Circuit Diagram Using a 2-Wire Strain Gauge
The following symbols apply to the circuit diagram and equations:
•
R
1
and R
2
are half-bridge completion resistors.
•
R
3
is the quarter-bridge completion resistor (dummy resistor).
•
R
4
is the active measuring element.
•
R
SCAL
is the shunt-calibration resistor.
AI
QTR
SCXI-1521/B
SCXI-1317
2-Wire Transducer
Ex+
R
4 (gauge)
–
+
–
+
V
EX
+
–
R
3 (QTR)
R
SCAL
GND
R
L
R
L
R
1
R
2
V
AI