Siemens simatic et 200s Operating Instructions Manual page 197

Connection of Relays and Contactors to the Digital Outputs
Note
Direct connection of inductivities (such as relays and contactors) is possible without external
circuiting.
If SIMATIC output circuits can be deactivated by additionally installed contacts (for example
relay contacts), you have to provide additional overvoltage protection devices at inductivities
(see the following example for overvoltage protection).
Overvoltage Protection Example
The following figure shows an output circuit that requires additional overvoltage protection
devices. Direct-current coils are wired with diodes or Zener diodes.
Figure 5-1
ET 200S Positioning
Operating Instructions, 05/2007, A5E00124871-04
Relay contact in the output circuit
1PosSSI/Digital
5.3 Terminal Assignment Diagram
197