Time-sharing communication system on basis of power grid

The invention discloses a time-sharing communication system on the basis of a power grid and particularly relates to a time-sharing communication method of a system consisting of a plurality of control devices which are connected onto the same power grid line and share one power supply switch and a LED (Light-Emitting Diode) point light source and LED rail guarding lamp display system adopting the method. All the control devices of the system are connected onto the same power grid line and share the same power supply switch. A power supply half-wave rectifying circuit is adopted in each control device and all the control devices share one rectifier diode, wherein a working power supply of the system is provided by a half-wave of a power grid cyclic wave; and other half-wave time blocked up by the rectifier diode is used for communication. The time-sharing communication is implemented by using a zero-crossing signal on the power grid cyclic wave as a synchronizing signal, continuously judging and counting the synchronizing signal, determining communication time by a count value and switching on or switching off an electronic switch.