Interbus

Interbus is a fieldbus system used for real-time digital communication in industrial automation. It connects programmable logic controllers, distributed I/O devices, sensors, and actuators over a single bus to enable structured, deterministic data exchange.

It originated in Europe during the 1980s as a standardized communications solution for factory automation. A consortium of equipment manufacturers promoted and maintained the protocol to ensure interoperability between devices from different vendors. Interbus gained widespread adoption in machine tools, packaging lines, and process control across multiple industries through the 1990s and into the early 2000s.

Technically, Interbus uses a master-slave architecture in which a central master polls connected devices along a daisy-chained bus. The architecture supports real-time cyclic data transfers, event-driven communications, and process alarms. The physical layer commonly employed two-wire shielded cable with daisy-chained topology, allowing relatively simple field installation and expansion. Several generations of the protocol were released, adding features such as expanded addressing and higher data throughput.

With the rise of Ethernet-based fieldbuses and industrial Ethernet standards, Interbus saw reduced new installations, though many legacy systems remain in operation. Vendors continue to provide bridges and migration paths to modern networks for existing installations. Interbus's influence is recognized in early automation design and as a stepping stone toward more modern fieldbus architectures.

See also: PROFIBUS, CAN, Modbus, Ethernet/IP, IEC 61158.