| 摘要 |
PURPOSE:To make easy the discovery of failed part, by connecting a plurality of input and output control mechanisms connected to a common bus to a cut-off signal line sequentially and performing the control for operating state, detaching state and returning state for the cut-off signal sequentially. CONSTITUTION:A plurality of input and output control mechanisms IOCE20-20n are connected in parallel with a common bus 3 connected to a controller 1 and in series between a cut-off signal line 5 and a return 6. When a controller 1 detects a failure on the common bus 3, a pulse is transmitted to a cut-off signal line 4 and inputted to the IOCE20. The cut-off signal is detached from the common bus 3 through the operation of filp-flops 11, 12 and a delay circuit 9, and the cut-off signal is not transmitted to the succeeding circuits from an AND gate 8. If the failure on the common bus 3 remains, the IOCE20 is connected to the common bus 3 with the next cut-off signal and it is transmitted to the next IOCE21. This is repeated and an IOCE vanishing the failure is obtained. Thus, the location of failure is simply discovered without physical detaching of the IOCEs from the common bus. |
