| 摘要 |
PURPOSE:To secure the mutual comminication among communication lines despite the disconnection of a communication line occurs by laying a main trunk line in a closed loop form and connecting the main trunk line with each communication terminal part with branch lines consisting of plural branched lines. CONSTITUTION:A main trunk line 2 is provided in a closed loop form and also connected with communication terminal parts 1A-1E with branch lines 3a-3e consisting of >=2 lines respectively. At the same time, a branch line 4' of a communication terminal part 4 is connected to another branched line 3a'; while a branch line 5' of a communication terminal part 5 is connected to a branched line 3a'' in the number of >=2 lines respectively for the line 3e of the terminal part 1A for example. In such a mutual communication system, the terminal part 1B is never isolated even if a disconnection occurs at an area Y. Furthermore the communication of data is secured for the parts 1A-1E despite a disconnection occurring to the line 2 at the point Z. Thus no communication terminal part is isolated at all. |
