Industrial Communication Guide

COMPONENTS AND STRUCTURE OF AUTOMATION SYSTEMS

2.5.5. DECENTRALIZED I/O SYSTEM

Every decentralized I/O system consists of a coupler and I/O con- nections or I/O modules. The coupler establishes the connection to the control unit (PLC), e.g. via a fieldbus. The individual sensors and actuators are connected to the I/O modules.

A decentralized I/O system consists of one or more network com- ponents connected to the PLC via fieldbuses or Ethernet, allowing direct connection of various sensors and actuators. The main advan- tage of a decentralized I/O system is that the sensors and actuators do not have to be wired up to the PLC but have a communication sys- tem in between: this greatly reduces the installation work involved.

Control computer (PLC)

Communication network

Decentralized I/O system

Decentralized I/O system

Actuator

Sensor Actuator

Sensor

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