Siemens Simatic S7-400 - Manual (Page 534)

Interface Submodules
13-38
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Isolated Measured Value Sensors
Potential differences can occur between the individual measured value sensors in
the case of isolated measured value sensors. These potential differences can
occur as the result of interference or the physical distribution of the measured value
sensors.
Note
Ensure that the V
CM
(common mode voltage) does not exceed the permissible
value. Violation of the permissible value can result in wrong measured values.
Figure 13-13 shows the connection of isolated measured value sensors.
+
-
V
E0
Isolated measured
value sensors
Ground bus
MV
0+
M
0-
+
-
V
E1
MV
1+
M
1-
+
-
V
CM0
+
-
V
CM1
M
SENSOR
Figure 13-13 Connection of Isolated Measured Value Sensors