Communication module, communication system and air conditioner

摘要

First and third current paths are connected at mutual one end, and second and fourth current paths are connected at mutual one end. A transmitter sends signals utilizing the change of a current by changing the current flowing between other ends of the first and second current paths. A switching part brings about a non-conductive state between the other end of the third current path and the other end of the fourth current path by being applied with a control signal from a controller. By contrast with this, the switching part brings about a conductive state between the other end of the third current path and the other end of the fourth current path by not being applied the control signal.

主权项

1. A communication module comprising:
first and second signal line connection terminals; a first current path having one end electrically connected to said first signal line connection terminal; a second current path having one end electrically connected to said second signal line connection terminal; a transmitter which sends a signal utilizing a change of a current by changing the current flowing between the other end of said first current path and the other end of said second current path; a third current path having one end connected to said one end of said first current path; a fourth current path having one end connected to said one end of said second current path; a switching part which switches a conductive/non-conductive state between the other end of said third current path and the other end of said fourth current path; a power source part provided without being electrically connected with said first and second signal line connection terminals; and a controller which is connected to said transmitter, said switching part and said power source part, and which operates with supply of power from said power source part, and which controls said transmitter and said switching part, wherein while said switching part brings about the non-conductive state between said other end of said third current path and said other end of said fourth current path by being applied with a control signal from said controller, said switching part brings about the conductive state between said other end of said third current path and said other end of said fourth current path by not being applied said control signal, and said switching part includes:
a transistor having a collector terminal connected to said other end of said third current path, an emitter terminal connected to said other end of said fourth current path, and a base terminal;a resistance electrically connected between said base terminal, and said one end of said third current path or said first signal line connection terminal;a photocoupler having a phototransistor connected between said base terminal and said one end of said fourth current path, and a light emitting diode; anda driving circuit connected to said controller and making said light emitting diode emit light by being applied with said control signal.