SWITCHING SYSTEM BETWEEN DUPLEXED SYSTEM AND SIMPLEXED SYSTEM

摘要

PURPOSE:To accurately switch a system even if a fault such as clock stack in a duplexed system occurs by outputting a standby identification signal when a frame in out of synchronism detection circuit and a stack supervisory circuit output the detection signals. CONSTITUTION:When the fault occurs in a frame clock, a master clock and/or a frame, all of which are extracted from the first extraction circuit 1 of a duplexed device, system switching identification information, a frame in out of synchronism alarm and/or a signal showing the stack of the master clock are generated from a second extraction circuit 3, the frame in out of synchronism detection circuit 5 and/or the stack supervisory circuit 7. Even if the extraction circuit 3 stacks a switching identification signal as an in-use system identification signal, the in-use system identification signal is outputted from a mask processing circuit 9 as the standby system identification signal. Thus, the system can accurately be switched without being influenced by the fault such as clock stack which occurs in the duplexed system.