| 摘要 |
PURPOSE:To attain normal changeover by supplying fault information to all control means and using each control means to monitor the presence and absence of the mounting of a link interface means and the presence and absence of a fault even when a master clock is selected to change over the system. CONSTITUTION:Each of four pulse monitoring circuits 287 in each control section 211 introduces package mount information 265 from four PCM link interface sections 213 in common. Thus, a PCM link interface section 213 having no error in the input data is selected as the PCM link interface section 213 mounted to the digital interface device 210 and an extracted clock 299 is selected switchingly by a changeover selection section 295 based on the mounted monitoring information 285 accordingly to offer the master clock. Thus, the master clock is selected normally. |
