Siemens Simatic M7-400 Reference Manual page 277

Figure 5-21
Two-Conductor Connection of Loads to a Voltage Output
In the case of a two-conductor connection, connect Q
the front connector. However, this will not produce the accuracy of a four-conductor
connection.
Connect the load to terminals Q
circuit M
ANA
Figure 5-22
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
+24 V
L
+
Q
V
S+
S–
M
ANA
M
0 V
Connecting Loads to a Voltage Output of an Isolated AO over a
Four-Conductor Connection
and to the reference point of the measuring
V
of the module.
+24 V
L
+
QV
S+
S–
M
ANA
M
0 V
Two-Conductor Connection of Loads to a Voltage Output of an Isolated AO
R
L
U
ISO
Chassis ground
to S+ and M
V
R
L
U
ISO
Chassis ground
Analog Modules
to S– on
ANA
5-61