Siemens M7-400, S7-400 Connection of Current Sensors as Two-Wire and Four-Wire Transducers

Interface Submodules
13-40 S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Connection of Current Sensors as Two-Wire and Four-Wire Transducers
Figures 13-16 and 13-17 show you how to connect current sensors as two-wire
and four-wire transducers to analog input modules.
The 24 V voltage is supplied to the two-wire transducer via a protected output (L1+,
L2+). The two-wire transducer converts the measured variable to a current of 4 to
20 mA. The range 4 to 20 mA is converted to the required format by a software
driver function.
Four-wire transducers have a separate supply voltage.
Two-wire
transducers
Two-wire
transducers
+24 V
Sensor,
e. g. pressure
gauge P
P
+
-
+
-
L+
M
L1+
M0-
MI1+
M1-
0 V
MI0- Vm
Vm
4 to 20
mA
4 to 20
mA
Figure 13-16 Connection of Two-Wire Transducers
+24 V
transducer Four-wire
+
-
+
-
Sensor,
e. g. pressure
gauge P
P
L+
M
MV0+
M0-
MV1+
M1-
VCM1
VCM0
0 V
Figure 13-17 Connection of Four-Wire Transducers