S7-400 Digital modules

Module spectrum


Digital actuators and sensors can be connected to a SIMATIC S7-400 via digital modules. The extensive range of modules allows the most suitable signal module to be selected in each case.

Area of application

Digital input/output modules contain digital inputs/outputs for the automation system. It is via these modules that digital sensors and actuators can be connected to the automation system. Switches and 2-wire proximity switches (BEROs) can be connected to input modules, for example. Output modules are suitable for connection of solenoid valves, contactors, small motors, lamps and motor starters.


The use of digital input/output modules provides the user with the following advantages:

  • Optimum adaptation:
    Since almost any combination of modules is possible, the number of inputs/outputs can be matched to suit the task in hand. Superfluous investments no longer exist

  • Flexible connection process:
    The wide variety of digital actuators and sensors facilitates connection of the automation system to the process

Design and functions

Digital output modules exhibit the following mechanical characteristics:

Compact design

The rugged sturdy plastic housing features:

  • Green LEDs for displaying the signal states at the inputs/outputs

  • One red LED each for displaying internal/external errors, for modules with diagnostic capabilities and for displaying faults, such as blown fuses and missing load voltage

  • Labeling strips for inserting in front connector (included in scope of delivery; also as template in manual); cover films also available

Easy assembly
Modules are hung into the rack and screwed into place.

User-friendly wiring
The modules are wired by means of a front connector. When they are first plugged in, a coding element clicks into place so that the connector will only fit into modules of the same type. When the module is replaced, the front connector can be used in its fully- wired state for a new module of the same type.