eBUS: a self-powered bus on 2 wires
A Saunier Duval or Vaillant boiler talks to its controller over two wires that also carry power: 2400-baud UART, SYN byte after 40 to 45 ms of silence, address arbitration by bitwise AND. Master-slave frame, escaping, CRC polynomial 0x9B. Every byte recalculated in Python from five real frames from public ebusd logs, no eBUS hardware.