| 摘要 |
PROBLEM TO BE SOLVED: To sharply increase validity and reliability in case of achieving a more desired bidirectional communicating function by a local watching system by transmitting emergency information or the like quickly and timely from a server computer (relay unit) side to a slave unit. SOLUTION: Relay units 3 and so on obtain common data Dw for synchronization by synchronization generation parts 7 and so on, and slave units 2 and so on obtain the data Dw for synchronization, and set a period Th exclusive for reception of each prescribed time Tw interval synchronously with the data Dw for synchronization. In case of transmitting slave unit control data Dc from a server computer 6 to the specific slave unit 2, when the interval of periodic notification Ds and so on of the slave unit 2 is a normal time (Ts), a first communication mode Mf in which the slave unit control data Dc are added to an ACK signal Dx from the relay unit 3 and are transmitted, is executed, and when the interval of the periodic notification Ds and so on is longer (Tm) than the normal (Ts), a second communication mode Ms in which the slave unit control data Dc are transmitted from the relay unit 3 in the period Th exclusive for reception is executed. COPYRIGHT: (C)2011,JPO&INPIT |
