Profibus

PROFIBUS is a family of fieldbus standards for industrial automation that enables communication between controllers, sensors, actuators, and other devices across factory and process environments. Initiated in the 1980s by a consortium led by Siemens and other equipment vendors, PROFIBUS established a vendor-neutral, open communications technology. The family comprises two main variants: PROFIBUS DP, designed for fast exchange of data with decentralized I/O and controllers, and PROFIBUS PA, intended for process automation with intrinsically safe operation in hazardous environments. A legacy variant, PROFIBUS FMS, was used in some factory applications in the 1990s and early 2000s.

Technically, PROFIBUS networks are typically organized as a daisy-chained bus with linear topology and short stubs to devices. A master/slave communication model governs operation, with devices addressed on the bus and data exchanged in cyclic or acyclic forms. PROFIBUS DP uses a high-speed RS-485 based physical layer, enabling data rates up to 12 Mbit/s, while PROFIBUS PA employs a slower, intrinsically safe physical layer (Manchester encoding) suitable for field instruments in process plants and hazardous areas, often powered from the bus. The networks require end-of-line termination and support on-field diagnostics, device addressing, and fault signaling.

Standards and deployment: The PROFIBUS family is standardized as part of IEC 61158 and related profiles for DP and PA, with governance by the PI (PROFIBUS & PROFINET International) organization. While increasingly complemented or replaced in new installations by Ethernet-based PROFIBNET protocols such as PROFINET, PROFIBUS remains in widespread use in many industries due to long-standing installations and robust fieldbus performance.