Guide - add a BACnet device on another subnet

Goal: a BACnet device on another subnet or VLAN is found and added through a BBMD.

Before you start

• A BBMD (BACnet broadcast management device) is available on the network of the device, and you know its address, for example 192.168.2.1:47808.
• The BBMD must accept Foreign Device registrations, and UDP port 47808 must be reachable between Home Assistant and the BACnet devices (general BACnet/IP networking advice).
• Only one program can use UDP port 47808 on a machine. Stop other BACnet programs on the same host, or choose a different port.

A BBMD forwards BACnet broadcasts between subnets. Without one, a Who-Is broadcast never leaves the local network, so devices on another VLAN are not found.

Steps

1. Go to Settings → Devices & Services → Add Integration and search for BACnet IP.
2. On the network page, leave Local IP address (bind) empty.
3. Tick Enable BBMD / Foreign Device Registration.
4. Fill in BBMD address (IP:port), for example 192.168.2.1:47808.
5. Leave Foreign Device TTL (seconds) at 900, or change it.
6. Optionally, fill in Target device address with the IP address of the device. Leave it empty to discover all devices.
7. Submit. The integration looks for devices and lists them in Select a BACnet device. Pick yours.
8. Choose the objects to import and click Submit.

You should see the device in the dropdown, and then its entities after step 8.

To change the BBMD of a device that is already added, open the ⋮ menu of the integration entry and choose Reconfigure. Entities and options are kept.

If it doesn't work

• "Foreign Device Registration with the BBMD failed": check the BBMD address (IP:port).
• "No BACnet devices were discovered on the network": enter the device address in Target device address.
• "Failed to connect to the BACnet network": check the network settings and the Home Assistant log.
• Still nothing: check that the device is reachable on UDP 47808.

More detail: Getting started and Troubleshooting.