Connection Of Isolated Sensors To An Isolated Analog Input Module - Siemens SIMATIC ET 200S Manual

Isolated sensors
The isolated sensors are not connected to the local ground potential. They can be
operated potential-free. Local conditions or interference can cause potential
differences U
channels and the reference point of the measuring circuit M
The following applies to ensure that the approved value for U
during operation in areas with high EMC interference:
• with the 2AI U, 2AI I 4WIRE and 2AI TC analog input modules: Connect M--
with M
• There must not be a connection from M-- to M
measurement transducers for current measurement and resistor sensors.
Isolated sensors, continued
Figure 12-1 shows the general connection of isolated sensors to the isolated
analog input modules..
Isolated
sensors
Recommended
connection
Figure 12-1
ET 200S Distributed I/O System
EWA-4NEB 780602402-12
(static or dynamic) between the M-- measuring lines of the input
CM
!
ANA
U
CM
Central ground point

Connection of isolated sensors to an isolated analog input module.

ANA
M+
:
M--
M+ ADC
: M --
M
ANA
U
ISO
Grounding busbar
Analog Electronic Modules
.
ANA
is not exceeded
CM
when connecting 2-wire
L+
M
Backplane bus
12-19