ModbusFieldbus

ModbusFieldbus is a generic term that sometimes refers to the Modbus protocol when used in an industrial fieldbus context. Modbus is a serial communication protocol, originally developed by Modicon (now Schneider Electric) in 1979 for use with its programmable logic controllers (PLCs). It is a de facto standard, widely adopted in industrial automation for its simplicity and robustness.

In a fieldbus application, Modbus enables communication between various industrial electronic devices such as sensors, actuators, and control systems. It operates on a master/slave (or client/server) architecture. The master (client) initiates requests and the slave (server) responds. Data is exchanged in discrete blocks, typically using functions for reading and writing coils (digital outputs), discrete inputs (digital inputs), input registers (analog inputs), and holding registers (analog outputs or configurable parameters).

Modbus supports several physical layers, most commonly RS-485 (Modbus RTU) for serial communication and Ethernet (Modbus TCP) for network communication. Modbus RTU is characterized by its compact, binary representation of data, making it efficient for serial lines. Modbus TCP encapsulates Modbus messages within TCP/IP packets, allowing for communication over standard Ethernet networks. The flexibility in its physical layer implementation has contributed significantly to its widespread adoption across diverse industrial environments. While not a true "fieldbus" in the sense of a standardized, real-time deterministic network like PROFIBUS or EtherNet/IP, Modbus is frequently employed in field applications due to its ease of integration and low cost.