Fieldbus

Fieldbus refers to digital, two-way communication systems used to connect industrial sensors and actuators with controllers such as PLCs and DCS. It replaces point-to-point wiring with a shared network, enabling real-time data exchange, straightforward diagnostics, and scalable architecture for plant-wide automation.

Several standards exist, defined by IEC 61158 and related publications. Common fieldbuses include Foundation Fieldbus, Profibus, DeviceNet, CANopen, and AS-Interface. Each uses a different physical layer and protocol, with interoperability governed by profiles such as IEC 61784. Foundation Fieldbus divides into H1 for field devices and HSE for high-speed Ethernet backbones.

Operation and topology: fieldbus networks are typically bus-based with master-slave or distributed control models. Devices are addressed on the network, allowing control loops, process data exchange, and diagnostics to occur over a single communication link. Foundation Fieldbus and Profibus offer real-time behavior and support for safety-enhanced variants, while integration with PLCs and SCADA systems enables centralized monitoring and asset management.

Impact and use: fieldbus reduces wiring effort and simplifies commissioning, contributing to scalable and flexible automation systems. It introduces design complexity and cost, but its use is widespread in process industries (with FF and Profibus-PA) and factory automation (DeviceNet, CANopen). The trend is toward integrated digital networks that combine fieldbus technology with Ethernet-based industrial networks for broader interoperability and higher performance.

---