| 摘要 |
PURPOSE:To enable an effective operation and an automatic operation of a cross call system, by executing a forcible cut-off instruction when the abnormal stop is happened at an upper device regardless of the state of the upper device. CONSTITUTION:Registers 10 and 11 which replace and record the device numbers of lower devices 7 and 8 every time upper devices 1-4 select the devices 7 and 8 are packed into controllers 5 and 6 respectively. Now the upper device 3 has an abnormal stop after selecting and reserving the lower device 7 via the controller 6. Thus the device number of the device 7 is recorded to a register 11 of the device 6. When the upper device 1 tries to select the device 7, the device 6 sends the busy informing that other systems are already reserved back to the device 5 via a cross call interface 9. The device 1 decides that upper devices 3 and 4 are abnormally stopped respectively when a certain time elapses, then delivers a forcible cut-off instruction to the device 5. |
