Siemens SIMATIC ET 200S Installation And Operating Manual page 125

Wiring Diagram for Application 2.3 - Connecting a Non-equivalent Sensor to Two Non-equivalent
Channels
Two channels of a non-equivalent sensor are connected nonequivalently to two inputs of the
F-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.
Note
If the voltage is supplied to the sensor by the F-DI module, you must use the internal sensor
supply Vs1. Connection to Vs2 is not possible.
The wiring is carried out on the appropriate terminal module.
Figure 7-27
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 for EM 4/8 F-DI DC24V - One Nonequivalent Sensor Connected
Nonequivalently via Two Channels, Internal Sensor Supply
Fail-Safe Modules
7-65