| 摘要 |
PROBLEM TO BE SOLVED: To obtain communication environment without collisions by transmitting a clock pulse by low outputting impedance and transmitting a data pulse by high outputting impedance. SOLUTION: A common control unit 12 includes an interface 12a for connecting to a communication medium 14, such as an electric cable, and plural surrounding condition detectors 18 and plural control and function units 20 are connected to the medium 14. The member 18 is an infiltration sensor or a fire sensor and the member 20 is control or function realizing unit and a display device driven by a solenoid. In addition, plural alarming instruction output devices 26 are connected to the unit 12 via a medium 24. An interface 12a supplies a clock signal at showing of low output impedance. The interface 12a is switched to a high impedance outputting state to receive data from the members 18 and 20. In addition, data are transmitted to the members 18, 20 during this time interval. |
