What Is Modbus?
One-line history (no more):
In 1979 Modicon created a simple communication protocol for their industrial PLCs, released it openly with no license fee, and within years it became the default language of industrial devices — forty-five years later Modbus is still in every building.
Modbus is like the share auto — fixed route, fixed stops, one driver (the master) asks each passenger (slave device) one by one: "Do you have data for me?" Simple, direct, reliable for straightforward data collection.
Modbus RTU — binary, over RS-485 cable. For field devices — meters, drives, sensors.
Modbus TCP — same protocol over Ethernet. For devices with Ethernet port.
Almost every energy meter, VFD, and chiller speaks Modbus. It is the Tamil of building protocols — old, deeply rooted, trusted everywhere, and refusing to be replaced.
Related Topics
- What is BMS integration? — how a BMS connects with VFDs, energy meters, BACnet/Modbus devices and other building systems
- How to design a BMS system step by step — the complete BMS design methodology covering site survey, IO list, controller selection, sequence of operations
- What is a Building Management System (BMS)? — fundamentals of BMS controls and architecture for HVAC, lighting, energy and access
- What is BMS commissioning? — the disciplined commissioning process that turns a BMS install into a working building brain
- Browse all Commissioning & Integration topics — more from this section of the EnSmart BMS Library