| 摘要 |
PURPOSE:To prevent the whole system from breaking down owing to the occurrence of a fault by providing two ports to an input-output channel and by connecting a device which can make a cross call to an input-output device input side, between both the ports. CONSTITUTION:Channel IOC has two ports IOC-P1 and IOC-P2, and cross-call devices CCH-1 and CCH-2 are connected to both the ports. Cross-call devices CCH are connected so that the cross call to respective input terminals of input-output device IOD-11, IOD-21... can be made. Now, when port IOC-P1 of the IOC is supposed to be in use while IOC-P2 be stand-by, ports IOC-P1 and IOC-P2 are changed over to the stand-by side and in-use side respectively if the hardware relating to IOC-P1 and CCH-1 gets out of order, and at the same time, cross-call devices CCH are also changed over. As a result, each input-output device can maintain a connection to IOC as well as that before the occurrence of the fault. |
