BACnet for IIoT Engineers: Object Types, COV Subscriptions, and the Building-Industrial Crossover [2026]

Most IIoT engineers live in the world of Modbus registers, EtherNet/IP CIP objects, and MQTT topics. BACnet — the dominant protocol in building automation — rarely appears on their radar. But as manufacturing facilities increasingly integrate HVAC, energy management, and environmental monitoring into their operational technology (OT) stacks, understanding BACnet becomes a practical necessity.
This article explains BACnet from the perspective of someone who already understands industrial protocols. If you can read a Modbus register map, you can understand BACnet's object model. The concepts map more cleanly than you might expect.