摘要 |
The present invention provides, in a system having a plurality of transmission control units which are connected to at least one circular type transmission line, a method of automatically checking the overlap of the addresses of the transmission control units in the circular type transmission system or automatically detecting the structure of the system. In addition, in a double loop transmission system which accompanies bypassing, a bypass route is constructed in correspondence with the occurrence of a fault in the system, and hence, the structure of the system changes. A conventional double loop transmission system does not include means to recognize the structure under which the system is presently operating, and this has been problematic in the maintenance of the system. The present invention is characterized in that the transmission control unit sends an address train message when, for example, it is to be started or it releases the bypass route, that the transmission control units having received the address train message enter their own addresses in succession so as to deliver the resulting messages to a transmission line, and that the source transmission control unit analyzes an address string in the message so as to check the presence or absence of the transmission control unit having the same address as the address of its own. Moreover, the analysis makes it possible to recognize the system structure at that time. |