Trunk cable fault detection and reconfiguration arrangement in a ring commnications network

Claim 1

An arrangement for maintaining the integrity of a connection ring between a plurality of line concentrators (10) in a ring communications network, each of said line concentrators including a ring-in port (16), a ring-out port (18), a plurality of station ports (20), a main connection path (44, 104) extending from said ring-in port through said station ports to said ring-out port, and an auxiliary connection path (48, 106) extending directly from said ring-out port to said ring-in port, the connection ring including a trunk cable (12, 14) extending from a ring-out port of a first line concentrator to the ring-in port of a second line concentrator, the trunk cable having a main portion (12) connecting the main connection path of said first line concentrator to the main connection path of said second line concentrator and an auxiliary portion (14) connecting the auxiliary connection path of said first line concentrator to the auxiliary connection path of said second line concentrator, with data communicated between said line concentrators being AC coupled through said ring-out ports and said ring-in ports, the arrangement comprising: voltage providing means (30) in said ring-out port of said first line concentrator for providing a fixed voltage on said trunk cable; first detecting means (32) in said ring-out port of said first line concentrator for detecting whether current due to said fixed voltage is present in said ring-out port; second detecting means (42) in said ring-in port of said second line concentrator for detecting whether current due to said fixed voltage is present in said ring-in port; first reconnecting means (50, 52) in said ring-out port (18) of said first line concentrator responsive to said first detecting means for connecting within said ring-out port the main connection path (44) of said first line concentrator to the auxiliary connection path (48) of said first line concentrator in the absence of current due to said fixed voltage; and second reconnecting means (100, 102) in said ring-in port of said second line concentrator responsive to said second detecting means for connecting within said ring-in port the main connection path (104) of said second line concentrator to the auxiliary connection path (106) of said second line concentrator in the absence of current due to said fixed voltage.