Siemens SIMATIC ET 200S Installation And Operating Manual page 127

Wiring Diagram for Application 2.3 - Connecting Two One-channel Sensors to Two Non-equivalent
Channels
Two channels of two 1-channel sensors are connected nonequivalently to two inputs of the
F-I/O module for each process signal (1oo2 evaluation).
The left-hand channels on the F-module (DI0 through DI3) supply the useful signals. If no
faults are detected, these signals will be available in the I/O area for inputs on the F-CPU.
The sensors can also be supplied via an external sensor supply.
Figure 7-29
Warning
To achieve AK6/SIL3/Category 3 using this wiring, you must use a sensor qualified for this
class.
Assignable Parameters for Use Case 2.3
Set the parameter "evaluation of sensors" to "1oo2 evaluation" for the corresponding input
and the parameter "type of sensor interconnection" to "2-channel nonequivalent". Deactivate
the parameter "short-circuit test."
ET 200S Distributed I/O System - Fail-Safe Modules
Hardware Installation and Operating Manual, 07/2005, A5E00103686-04
7.5 4/8 F-DI VDC24V PROFIsafe Digital Electronic Module
Wiring Diagram EM 4/8 F-DI DC24V - Two Channels of Two 1-Channel Sensors
Connected Non-Equivalent, Internal Sensor Power Supply
Fail-Safe Modules
7-67