| 摘要 |
PURPOSE:To attain surely switching to a spare at a high speed at a fault of a digital runk by providing an address converting circuit and a highway changeover circuit to a digital trunk module common section. CONSTITUTION:Digital trunks 70-73, a spare system digital trunk 74, common control section 6 and changeover switches 80-83 are mounted into a digital trunk module 4 while being divided into separate packages respectively. The common control section 6 is provided with an address converting circuit possible for control by the identical address at the changeover between a faulty digital trunk and a spare digital trunk and a highway changeover circuit. When a fault takes place in the digital trunk 73, it is detected by a controller 3, a command to switch to the common control section 6 is fed, which switches the trunk to the spare digital trunk. |
