A device, method and system for testing in situ the wiring between a data terminal equipment and a ring or similar type local area network having a loop conduction path with a plurality of data terminal equipment (DTE) coupled to said loop conduction path. The DTE is provided with a mechanism for generating...http://www.google.de/patents/US4551671?utm_source=gb-gplus-sharePatent US4551671 - Terminal disconnect and media wire fault detect mechanism
