| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of messages transmitted and received at the time of acquiring survival information of a relay device and a slave device in which a master device is connected with a low-order device in a radio communication network system having a tree structure. SOLUTION: Each of a slave device 40 and a relay device 30 transmits a survival informing message for a master device 20 for each determined time instructed by a timer 14. The master device 20 performs reception check of the survival informing message transmitted for each of them for each predetermined time. If reception of the survival informing message is checked, it determines that a slave device 40 or relay device 30 that is a source origin for transmitting the survival informing message is active, but if reception of the survival informing message is not checked, it determines that the slave device 40 or relay device 30 that is a source for transmitting the survival informing message is not active, then stores survival or non-survival information of the slave device 40 and relay device 30, which is obtained by the determination, in a network construction information storing section 16 as low-level device survival information. COPYRIGHT: (C)2011,JPO&INPIT
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