Slave suitable for energy management systems and energy management system

An energy management system comprising:

• a slave configured to obtain, from an energy meter for measuring an amount of electric energy supplied from a power source to a predetermined place through a distribution line, meter-reading data containing the amount of electric energy;
• an upper device configured to obtain the meter-reading data from the slave;
• a communication terminal configured to obtain the meter-reading data from the slave,
• the slave including:
• a first interface unit configured to communicate with the upper device;
• a second interface unit configured to communicate with an electric appliance installed in the predetermined place;
• a third interface unit configured to perform first wireless communication using an electric wave with the communication terminal;
• and
• a controller having:
• a function of obtaining the meter-reading data from the energy meter;
• a function of controlling the first interface unit to send the meter-reading data to the upper device;
• and a function of controlling the third interface unit to send the meter-reading data to the communication terminal,
• one of the first interface unit and the second interface unit being a wired communication unit configured to perform power line communication using the distribution line, and
• the other of the first interface unit and the second interface unit being a wireless communication unit configured to perform second wireless communication using an electric wave,
• wherein the controller includes:
• a channel selector configured to select a communication channel to be used for wireless communication from a plurality of channels,
• an interference evaluator configured to judge whether interference of electric waves occurs in the communication channel, and
• a change instructor configured to provide a change instruction to the channel selector when the interference evaluator determines that the interference occurs;
• the channel selector is configured to change the communication channel in response to reception of the change instruction from the change instructor;
• the channel selector is configured to designate a second communication channel to be used for the second wireless communication;
• the third interface unit is configured to judge whether use of the communication terminal is started;
• the change instructor is configured to, when the third interface unit determines that use of the communication terminal is started, provide to the channel selector the change instruction that indicates, as the second communication channel, a channel that does not cause interference with a channel used by the communication terminal;
• and
• the channel selector is configured to, when receiving the change instruction from the change instructor, change the second communication channel to the channel indicated by the change instructor.