| 摘要 |
PROBLEM TO BE SOLVED: To prevent crosstalk at transmission to a parent device by preventing the malfunction of a sensor of a child device, between a parent device and a plurality of child devices. SOLUTION: A timing signal is transmitted from a parent device MS, and a plurality of child devices BRk receive it. Each of child devices presets an operation timing with a first delay time elapsed since the reception timing of the timing signal from the parent device so that operation periods do not overlap each other when sensors SNS are operated. Detection signal Sbk of detection result with the sensor is outputted to a CPU2. The transmission timing with a second delay time elapsed since the reception timing of the timing signal from the parent device is preset so that the transmission periods with transmission circuits of the child devices do not overlap each other. When the detection signal Sbk is inputted, it is transmitted as a detection signal Pbk to the parent device. The parent device discriminates from which child device the detection signal comes based on the time difference between the reception timing of the detection signal Pbk and the transmission timing of the timing signal, for outputting an alert signal. |
