Glossary · Automation fundamentals, platforms and components
Decentralized periphery (distributed I/O)
Also known as: Distributed I/O, Remote I/O, Decentralized I/O
German: Dezentrale Peripherie
In industrial automation, decentralized periphery (distributed I/O) means input and output modules installed close to the sensors and actuators in the field and connected to the controller over a fieldbus or industrial Ethernet, instead of wiring every signal back to the control cabinet.
- Automation components
In one sentence
Distributed I/O places input and output modules near sensors and actuators and links them to the controller via fieldbus or industrial Ethernet.
Example
Each conveyor section has an IP67 I/O block that connects the local sensors and communicates with the central PLC over PROFINET.
How it applies
- Engineering: Distributed I/O reduces cabling and supports modular machines. Stations can sit in local cabinets or be mounted directly on the machine in high protection classes.
- Commissioning: Each station needs a network name or address and correct configuration in the controller project.
- Maintenance: Diagnostics per channel speed up troubleshooting; some systems allow module replacement during operation.
- Documentation: Show station locations, addresses and signal assignment. The term "decentralized periphery" comes from Siemens terminology (SIMATIC ET 200); many other sources say distributed or remote I/O.
Distributed I/O vs. distributed control
With distributed I/O, only the signal connection is decentralized; the logic still runs in the central controller. In distributed control, the logic itself runs on several controllers, as in a DCS or IEC 61499 applications.