In multidrop applications it is necessary that information coming from one serial port be received by multiple remote devices. This is commonly implemented using RS485 multidrop bus wiring. Multi-drop applications normally use modbus or another higher level protocol to address individual remote units. These protocols append addresses to the data packets sent packets to all the nodes through one serial port (RS485) that has multiple devices connected.
Digi radios work very well in wireless multidrop bus systems because by default, when one radio transmits, all others within range receive.