Issue
In EBO BACnet device discovery, how is the BACnet MAC address defined?
Product Line
EcoStruxure Building Operation
Environment
- Building Operation Automation Server
- Building Operation Automation Server Premium
- Building Operation Automation Server Bundled
- Building Operation Enterprise Server
Cause
A BACnet device is uniquely identified by a network number and a MAC address.
Resolution
BACnet MS/TP
A BACnet MS/TP device supports device MAC addresses in the range 0-127 for masters and 0-254 for slaves. Device MAC addresses are often configured using DIP switches or a configuration tool.
BACnet/IP
MAC addresses for BACnet/IP devices are a combination of the IP address and BACnet/IP UDP Port expressed in hexadecimal notation.
For example, if a BACnet/IP device is configured with an IP address of 192.168.1.5 and a UDP port of 47808 then:
IP address expressed in hexadecimal is 192 = C0, 168 = A8, 1 = 01, 5 = 05
UDP port expressed in hexadecimal is 47808 = BAC0
Therefore the MAC address will be, C0:A8:01:05:BA:C0
BACnet/SC
BACnet/SC nodes are identified by their 6-octet virtual MAC (VMAC) address in form of a IEEE EUI-48 identifier which is randomly generated. A BACnet/SC device attempts to resolve its own VMAC in the network. If it detects another device is already using this VMAC, it will generate a new Random-48 VMAC address and try again.
