Siemens SIMATIC ET 200S Manual page 24

Connecting
5.1 Connecting measuring sensors
Abbreviations used
The meanings of the abbreviations in the figures below are as follows:
M +
M -
M
ANA
M
L +
U
CM
U
ISO
Isolated measuring sensors
The isolated measuring sensors are not connected to the local ground potential. They can be
floating. Depending on local conditions or interference, potential differences U
dynamic) can occur between the measuring lines M- of the input channels and the reference
point of the measuring circuit M
The following figure illustrates the basic connection of isolated measuring sensors to the
floating analog input modules.
Connection of isolated measuring sensors to a floating analog input module:
5
Figure 5-1
①
②
③
④
⑤
24
Measuring line (positive)
Measuring line (negative)
Reference potential of the analog measuring circuit
Chassis terminal
Rated load voltage 24 VDC
Potential difference between inputs and reference potential of the measuring
circuit M
ANA
Potential difference between M
mA
mA
4
Connection of isolated measuring sensors
Logic
Backplane bus
Ground bus
Central grounding point
Isolated measuring sensors
and central grounding point
ANA
.
ANA
1
3
2AI I 2WIRE HS analog electronic module (6ES7134-4GB52-0AB0)
2
Manual, 01/2008, A5E01001734-02
(static or
CM