| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a communication system suitable for securing security and reducing the introduction cost and running cost. <P>SOLUTION: A monitoring system O2 includes a security signal transmission device O221 that transmits a security signal, a signal branching device O222 that branches the security signal from the security signal transmission device O221 into a security signal to a data collection device O223 and a security signal to a transmission device N7 at the physical layer level and at the same time, branching a response signal from the transmission device N7 into a response signal to the data collection device O223 and a response signal to the security signal transmission device O221 at the physical layer level, and a data collection device O223 that receives the security signal from the signal branching device O222 and a response signal from the signal branching device O222 corresponding to the security signal. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
