User manual

Chapter 5 Transducer Conversion Functions
NI-DAQ User Manual for PC Compatibles 5-6 ni.com
Figure 5-1. Strain Gauge Bridge Configuration
bridgeConfig = 7 (FULL_BRIDGE_III)
strain (ε)=
-2Vr
GF [(
v +1)-Vr( v - 1)]
bridgeConfig = 3 (HALF_BRIDGE_I)
-4Vr
GF [(1 +
v )-2Vr( v - 1)]
strain (ε)=
•
()
1+
RL
Rg
Vex
VOUT
-
+
-
+
Rg (+ε)
Rg (-vε)
RL
RL
R1
R2
RL
bridgeConfig = 4 (HALF_BRIDGE_II)
strain (ε)=
-2Vr
GF
•
()
1+
RL
Rg
Vex
VOUT
-
+
-
+
Rg (+ε)
Rg (-ε)
RL
RL
R1
R2
RL
bridgeConfig = 5 (FULL_BRIDGE_I)
strain (ε)=
-Vr
GF
Vex
-ε
-ε
+ε
+ε
VOUT
-
+
-
+
Vex
-v ε
-v ε
+ε
+ε
VOUT
-
+
-
+
bridgeConfig = 6 (FULL_BRIDGE_II)
strain (ε)=
-2Vr
GF (
v +1)
Vex
-v ε
- ε
+ε
+
v ε
VOUT
-
+
-
+
RL
Vex
VOUT
-
+
-
+
R1
R2
R3
Rg (e)
RL
RL
strain (ε)=
•
()
1+
RL
Rg
-4Vr
GF (1 + 2Vr)
bridgeConfig = 1 (QTR_BRIDGE_I)
RL
Vex
VOUT
-
+
-
+
Rg (ε)
Rg (dummy)
RL
RL
R1
R2
strain (ε)=
•
()
1+
RL
Rg
-4Vr
GF (1 + 2Vr)
bridgeConfig = 2 (QTR_BRIDGE_II)