Fieldbuses

Fieldbuses are digital, real-time networks that connect sensors, actuators, and controllers in industrial automation. They consolidate I/O wiring by using a shared bus to carry data and, in many cases, power, enabling distributed control, diagnostics, and configuration of devices across a factory floor or process plant.

Fieldbus networks organize communication with a defined protocol, device addressing, and real-time messaging. They provide determinism, cycle timing, and fault-handling features that support safety and reliability in harsh environments. Typical topologies include trunk-and-branch and ring layouts, with redundancy options in many implementations. Standards bodies and IEC fieldbus families guide interoperability and safety.

Notable fieldbus families include Profibus (DP for factory automation and PA for process automation), Foundation Fieldbus (FF H1 for process instrumentation with power on the bus), Modbus (serial and TCP variants used widely in SCADA and simple devices), CAN-based networks such as CANopen, AS-Interface (AS-i) for simple field devices, DeviceNet and Interbus. These networks differ in speed, device count, power delivery, and ease of integration with controllers like PLCs and DCS.

Fieldbus technology has largely evolved to industrial Ethernet in many applications, offering higher bandwidth and standard IT infrastructure compatibility, while fieldbus standards remain in use where legacy equipment, high determinism, or process integration requirements persist. The term fieldbus remains a generic descriptor for these families of industrial networks rather than a single protocol.