| 摘要 |
<p>PURPOSE:To prevent the test condition from continuing limitlessly even when any station in a loop does not give a loopback test indication by using a indication from a comparison/selection circuit so as to bring a test bit into a non-test state for a prescribed time at a prescribed period, and correcting the test bit into the original test state from the non-test state. CONSTITUTION:When a modified test bit comes from a detection circuit 23 not during the loopback test, a comparison/selection circuit 25 references a signal '0' from a switch state storage circuit 24 and discriminates that the detected test bit is an incorrect test bit generated at the leading of the system, issues a correction indication to a test bit correction circuit 26 and a indication as it is to a test bit modifying circuit 27 respectively. The test bit correction circuit 26, based on the said indication, brings the non-test state of the test bit into the original test state. Thus, a loop synchronous control station 1 is not brought into the test state by the incorrect test bit.</p> |
