BACnet Port Connection Lost
The BACnet port (MS/TP or IP) has lost connectivity. Devices on that port become unreachable. Often logged by routers, gateways, or supervisory controllers.
Common Causes
- RS-485 trunk wiring fault: open, short, or disconnected
- MS/TP token ring failure or trunk not responding
- Router/gateway power loss or firmware hang
- IP network issue (DHCP, firewall, or cable) for BACnet/IP ports
Fix Steps
- For MS/TP: verify RS-485 wiring, termination, and voltage at the router port.
- Check router/gateway power and status LEDs; power-cycle if needed.
- For IP: confirm Ethernet link, IP address, and BACnet port 47808.
- Rescan the MS/TP trunk to rebuild token ring; check for offline nodes.
- Review recent changes (cabling, config, firmware) that could have caused the drop.