Connecting Loads/Actuators To Voltage Outputs - Siemens SIMATIC S7-400 Reference Manual

Analog modules

5.15 Connecting loads/actuators to voltage outputs

5.15 Connecting loads/actuators to voltage outputs
Connecting loads to a voltage output
Connecting loads to a voltage output is possible both in a 4-conductor and a 2-conductor
connection.
Note
The cables required to connect the analog output module are not drawn in the figures shown
below.
In other words, you must continue to read and follow the instructions in the section "Connecting
loads/actuators to analog outputs", which contains general information on connecting sensors.
4-conductor connection of loads to a voltage output
You can use the 4-wire technique to achieve a high accuracy at the load by wiring the S- and
S+ sensor lines directly to the load. This results in direct measurement and correction of the
voltage at the load.
Faults or a voltage drop can result in a potential difference between the sensor lead S- and
the reference circuit of the analog circuit M
the permissible value. A negative influence on the accuracy of the analog signal is otherwise
inevitable.
Figure 5-18
L +:
Q :
V
S +:
S -:
220
+24 V
L+
Q
V
S+
S-
M
ANA
M
0 V
4-conductor connection of loads to a voltage output of an electrically isolated analog output
module
Terminal for 24 VDC supply voltage
Analog output voltage
Sensing line (positive)
Sensing line (negative)
. This potential difference (U
ANA
R
L
U
ISO
1
Reference Manual, Ausgabe 11/2016, A5E00850736-08
) must not exceed
CM
S7-400 Automation System Module Data