SCXI-1321 Terminal Block Installation Guide 10 ni.com
Assuming a strain-gauge range with a gauge factor of GF = 2 and a
quarter-bridge configuration, this range corresponds to ±1,498 µε, as given
by the strain formula for a quarter-bridge strain-gauge configuration:
where
Figure 3. Quarter-Bridge Nulling Circuit
ε4Vr
–
GF 12Vr
+()
-------------------------------=
Vr
strained voltage static unstrained voltage–
Vexc
--------------------------------------------------------------------------------------------------------=
CH+CH+
CH–
EX+
EX–
+
–
+
–
R1
R2
4.5 kΩ
4.5 kΩ
RSCAL
301 kΩ
RTrim
10 kΩ
RNull
39.1 kΩ
(Screw Adjusts Potentiometer)
RL
RL
RL
R3(dummy)
R4(gauge)
EX+
CH+
CH+
CH–
EX+
EX–
RTrim
SCXI-1121 SCXI-1321 Transducer
VEX
Note: R1 and R2 are completion resistors.