| 摘要 |
PURPOSE:To prevent hindrance to communication by changing systems after the modification of a line gate memory in a data switch when a changeover from an active system to a stand-by system. CONSTITUTION:Once fault detection circuit FDT3 detects a fault occurring to active ACT system, FDT3 sends system-switching request signal 6 to system supervisory circuit SCENT5. On receiving this signal, SCNT5 exercises a supervision over the state of data switch DS1 of the stand-by SBY system and after it is made sure that a line gate memory in this DS is not in process of modification, system switching unit EMA4 changes the ACT system of the data switch over to the SBY system. When the line gate memory in the data switch is in process, SCNT5 sends system-switching indication signal 7 out after the completion of the modification. |
