| 摘要 |
PURPOSE:To discriminate the trouble of a main trunk or a subtrunk easily with remote control or the like by storing the long of loop back release with respect to a primary-side loop back mechanism and a secondary-side loop back mechanism and locating the trouble in the main trunk or the subtrunk in accordance with the log of loop back release. CONSTITUTION:When the trouble is located in case that the subtrunk is disconnected, a release log flag 14 is initialized to ''0'', and light is outputted from an E/O transducer 8B to the subtrunk 2. This light does not reach an O/E transducer 9A because of disconnection of the subtrunk 2. Consequently, loop back due to a secondary-side loop back mechanism 5A is not released, and the release log flag 14 is held at ''0'' as it is. The state of the release log flag 14 is checked to detect that the release log flag 14 is ''0'', thereby detecting the trouble of the subtrunk 2. |
