Bus communication scheme for large number of devices (255+ nodes)?
DMX512 can support that many devices. Its main use is for stage lighting control. It’s very, very primitive, relying heavily on manual setup to define devices and addresses (no self-enumeration or discovery.) Uses RS-485, and has a backhaul path that’s not well regarded. Nevertheless it’s popular owing to its simplicity and stage-friendly cabling.
That said, it’s 2020 already. Maybe consider a wireless IoT protocol like LoRa, ZigBee or Bluetooth instead?