JPS567154A - Double system - Google Patents

Abstract

PURPOSE: To realize the switching between the main system and the stand-by system in a highly accurate and assured way, by giving both the self-diagnosis function and the mutual diagnosis function to two units of the higher-rank computers each plus the function to give the diagnosis for the higher-rank computers to the lower-rank computer and then combining these three diagnoses.

CONSTITUTION: Main system 10-A and stand-by system 10-B of the higher-rank computer receive the same signal through system bus 1 and then perform the same operation. Thus the control command is given from the main-system computer, and the both systmes possess self-diagnosis means SDA and SDB plus mutual diagnosis means MDA and MDB which give the diagnosis to the fault of the other side to each other. Lower-rank computers 20-IW20-N also possess self- diagnosis means SD₁WSD_n plus fault detecting means MD₁WMD_n which check the rationality of the control order given from the higher-rank computer to detect the fault of the higher-rank computer. When the fault is detected through these diagnosis means and fault detecting means, the detection signal is sent to switching decision circuit 30. At circuit 30, the fixed weighting is given to each detection signal and then the addition is carried out. When the addition output reaches the fixed weight, the control order is switched to the stand-by system from the main system through the higher-rank computer.

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