TRANSMISSION LINE SWITCHING SYSTEM AT ABNORMAL MULTIPLE ADDRESS COMMUNICATION

PURPOSE:To expand a system without being aware of a specific management node by implementing abnormality detection and switching of a transmission line entirely according to the multiple address communication system. CONSTITUTION:Nodes 1, 2 make an alive report to all nodes respectively through a 1st transmission line 3 for a prescribed period in the transmission line switching system at the time of abnormal multiple address communication, each node receives the existence report from all nodes and when each node does not receive the existence report from any node within a prescribed time interval, each node sends a dead recognition message of the node via a 2nd transmission line to all nodes and the node receiving the dead recognition message of its own station sends the existence report and the switching instruction of a transmission line through which a user message is sent to all the nodes through the transmission line 4 and each node makes the switching of the transmission line. Thus, the fault at the time of the fault of a management node is easily detected.