Siemens ET 200S Manual page 401

Non-Isolated Measuring Sensors
The non-isolated measuring sensors are connected to the local ground potential.
You must connect M
interference, potential differences U
locally distributed measuring points.
If the permitted value for U
the measuring points.
Figure 12-2 illustrates the connection of non-isolated measuring sensors to a
floating analog input module.
Non-isolated
measuring
sensors
Potential
equalizing line
Figure 12-2
Operating Four-wire Measuring Transducers on an External Voltage Supply
If there is isolation between the output and the supply of the measuring transducer,
you can connect it to the 2AI I 4WIRE without additional connections.
If there is no isolation between the output and the supply of the measuring
transducer, you can connect it to the 2AI I 4WIRE only if the reference potential of
the power supply voltages (24 VDC) is the same.
If there is an increase in interference radiation, a connection between M– and M
on the terminal module of the 2AI I 4WIRE is recommended.
Distributed I/O System ET 200S
EWA 4NEB 780 6024-02 07
to the ground potential. Depending on local conditions or
ANA
CM
is exceeded, there must be equalizing lines between
CM
M+
M–
M+
M–
U
CM
M
ANA
U
ISO
Ground bus
Connection of Non-Isolated Measuring Sensors to a Floating Analog Input
Module
Analog Electronic Modules
(static or dynamic) can occur between the
L+
M
ADC
Backplane bus
ana
12-45