Device network system

A system-recognizing device that, in a device network in which communication is established between a plurality of devices, uses a low-frequency signal of a frequency lower than a first frequency used in the communication to perform system recognition processing that identifies a device connected by a wired line, wherein

• a signal of the first frequency is used to transmit predetermined instruction information,
• the low-frequency signal includes
• first information for connection to a network, and
• identification information of a group to which a device to which the low-frequency signal is transmitted belongs, and
• the predetermined instruction information is transmitted to a device that
• has received the low-frequency signal,
• has registered the first information, and
• has connected to the network, and
• for which participation in the network has been approved.