Siemens simatic et 200s Operating Instructions Manual page 316

1PosUniversal/Digital
7.3 Terminal Assignment Diagram
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 7-1
316
Relay Contact in the Output Circuit
Operating Instructions, 05/2007, A5E00124871-04
ET 200S Positioning