Glossary · Automation fundamentals, platforms and components
BACnet
Also known as: Building Automation and Control Networks
German: BACnet
In building automation, BACnet (Building Automation and Control Networks) is a data communication protocol standardized as ANSI/ASHRAE 135 and ISO 16484-5. It models devices as collections of standard objects and properties that other devices can read, write and subscribe to.
- Automation components
- Standards
In one sentence
BACnet is a standardized protocol (ASHRAE 135, ISO 16484-5) for building automation devices such as HVAC, lighting and access control.
Example
The heating controller exposes its supply temperature as a BACnet analog input object, which the building management system reads over BACnet/IP.
How it applies
- Engineering: BACnet runs over several network types, most commonly BACnet/IP and BACnet MS/TP over RS-485. Integrators map plant data points to BACnet objects such as analog inputs, binary outputs and schedules.
- Commissioning: Device instance numbers, network numbers and object names must be unique and consistent with the point list.
- Security: Classic BACnet has little built-in security; BACnet Secure Connect (BACnet/SC) adds TLS-based communication. Networks should still be segmented.
- Documentation: Supply a point list and the device's protocol implementation conformance statement (PICS), and describe which objects are writable.
BACnet vs. LonWorks
Both are open building automation technologies. LonWorks is based on the LonTalk protocol (ISO/IEC 14908), while BACnet defines an object model and services over several transports. Buildings often contain both, linked by gateways. Note that BACnet is a Protocol (communication) with a built-in object model; the data model of a specific building is still project work.