Summary of "What is Profibus and how Profibus works ?"

Key Information

Profibus Overview: Profibus stands for Process Field Bus and is an open standard industrial communication protocol, OSI compliant and widely accepted in process automation and material handling.
Development History: Initiated in 1989 by the German Federal Ministry of Research and Technology in collaboration with automation manufacturers, Profibus is now standardized under the PI Organisation, which also oversees Profinet technology.
Global Popularity: Profibus is nearly universal in Europe and has significant usage in North America, South America, Africa, and Asia.

Features of Profibus

Connector and Network Capacity: Utilizes a 9-pin D type connector; supports up to 32 nodes without repeaters and 127 with repeaters.
Distance and Data Speed: Total network length can reach 24 km with repeaters and optical fiber; data speeds range from 9.6 kbps to 12 Mbps.
Message Size: Supports messages of up to 256 bytes (244 bytes of data plus 12 bytes overhead).
Communication Mechanisms: Uses polling and token passing for messaging.

Device Types

Master Devices: Control the bus and can send messages without a remote request (e.g., PLCs).
Slave Devices: Typically input devices like sensors and actuators that respond to master requests.

Variants of Profibus

Profibus DP: Focuses on decentralized peripherals, allowing I/O blocks to be placed in the field, reducing wiring costs.
Profibus PA: Designed for process automation, it simplifies connections by allowing sensors to connect to a single bus, eliminating the need for I/O blocks in the field.

Electrical Interface

Utilizes Fiber Optic or RS-485 as its electrical interface, with the network topology being a linear bus terminated at both ends. It employs twisted pair cables, usually shielded, and has two cable types depending on transmission speed.

Communication Types

Token Passing: Used for communication among multiple masters, forming a logical ring.
Polling: Used for communication between masters and slaves.