| 摘要 |
PURPOSE:To attain smooth exchange by changing all attendant boards into the day/night switching system if a fault takes place in a master attendant board in the master attendant board day/night switching system to prevent faulty switching of the system day/night mode. CONSTITUTION:If a fault takes place in a control circuit ATC of a master attendant board M-ATT and a central processor CC detects that the control is disabled, the controller CC changes over the system to the day/night switching system provided in a main storage device MM, and a failed board M-ATT is handled as the night mode. When the system is in the night mode, an incoming call is connected distributingly to night attendant boards S-ATT1-3. when the night switching is operated at night next, all the boards S-ATT1-3 are switched to the night mode and an incoming call is connected to a night attendant board N-ATT. |
