| 摘要 |
PURPOSE:To attain data transmission in nearly real time regardless of polling period by providing a discrimination function of a sending request of an emergency data to a terminal device and sending the data with high emergency from a terminal side to a central unit unidirectionally. CONSTITUTION:A data MODEM 24 applying demodulation to an outgoing frequency f1 and applying modulation to an incoming frequency f2 in a terminal device is connected to a CATV line. A communication control CPU 25 performs own call discrimination based on an address data, transmission control of a reply data in response to command data included in a call signal and further CSMA communication control when a sensor detection signal with high emergency being an object to a carrier sense multiple access (CSMA) transmission is obtained. Thus, plural sensors 27a-27c are connected to the CPU 25 via an I/O port 26, further controllers 28a-28c are connected and when a control command is included in command data included in the call signal, the corresponding controller is operated based on the command.
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