fieldbusses

Fieldbusses are digital, two-way communication networks used in industrial automation to connect field devices such as sensors, actuators, and other instrumentation to control systems. They enable real-time data exchange over a shared bus, reducing wiring, supporting distributed control, and enabling remote diagnostics. The term covers a family of standards developed to replace point-to-point wiring and to provide scalable, modular automation. Fieldbusses emerged mainly in the 1980s and 1990s and have become foundational in both process and manufacturing environments.

Typical fieldbus architectures use trunk-and-branch or daisy-chain topologies, with devices connected along a common channel. Communication is designed to be deterministic, using master-slave, token-passing, or peer-to-peer schemes to achieve real-time behavior. Some fieldbusses supply power to devices on the same two wires (as in Foundation Fieldbus H1); others use separate data and power rails. Fieldbusses support device diagnostics, parameterization, and remote maintenance, and many incorporate safety or redundancy features to improve reliability.

Major families include Profibus (with DP for factory automation and PA for process industries), Foundation Fieldbus, Modbus (serial and TCP), CANopen, DeviceNet, CC-Link, and AS-Interface. While historically associated with specific sectors, many fieldbusses are now complemented or replaced by Industrial Ethernet variants, offering higher bandwidth and standard Ethernet interoperability.

Today, fieldbusses remain common in many process and equipment environments, particularly where proven field devices and mature vendor ecosystems exist. They coexist with modern Ethernet-based control networks, often as part of migration strategies for existing plants. Limitations include vendor lock-in, configuration complexity, and relatively lower data throughput compared with high-speed Ethernet.