| 摘要 |
PURPOSE:To prevent a single fault of each I/O unit from exerting influence on the whole device, and also to replace the I/O unit without stopping the device, by separating an I/O bus from a common bus physically and logically. CONSTITUTION:Each I/O 4-1, 4-2, ...is connected to an I/O bus 5, and is not connected directly to a common bus 2 of a processor 1. The common bus 2 and the I/O bus 5 are connected through an adaptor 6. The I/Os 4-1, 4-2, ...constitute an I/O unit group which are designed so that the unit can be inserted and detached in a state that an electric power supply is applied. On the adaptor 6, a bus separating switch is provided. In this way, even if one of the I/Os 4-1, 4-2, ...becomes faulty, its I/O can be separated from the common bus, and also can be replaced. |
