What is a BACnet device instance?
By Bassirou Thiam, building automation engineer · Updated
The BACnet device instance is the number that identifies a device across the whole BACnet internetwork, like a numeric name the front end uses to find it. It ranges from 0 to 4,194,302 (4,194,303 is a wildcard) and must be unique on the internetwork, whatever trunk the device sits on.
Instance versus MAC address
The MAC address locates a device on its trunk; the device instance identifies it everywhere. A device moved to another trunk changes its MAC address but can keep its instance.
Numbering scheme: BACnet addressing.
Sources
Related
GuidesBACnet device instance numbering and MS/TP addressingThe rules for BACnet device instances, MS/TP MAC addresses, Max Master and network numbers, with segment limits and a numbering scheme you can reuse.
GlossaryWhat is an MS/TP MAC address?Definition of the BACnet MS/TP MAC address: the device address on its RS-485 trunk, valid ranges for masters and slaves, and Max Master.
GlossaryWhat is BACnet MS/TP?Definition of BACnet MS/TP (master-slave/token-passing) over RS-485: how it works, addressing, and the segment limits that shape a BAS riser.