| 摘要 |
PURPOSE:To attain the redundant digital control with high reliability by adding a function which turns off forcibly an output through a contact output device in case a CPU is faulty and using an OR gate to switch the CPU. CONSTITUTION:Both CPU-A and CPU-B systems 5 and 6 are always performing the self-diagnosis processing and then turn on the CPU-A and CPU-B system fault signals if the faults of both systems are detected. These fault signals are supplied to the input terminals of forcible open signals of contact output devices 17 and 18 respectively. Therefore the output signal of the device 17 is forcibly turned off regardless of the digital output value of the system 5 when a fault of the system 5 is detected. In the same way, the output signal of the device 18 is forcibly turned off when a fault of the system 6 is detected. In such a way, a contact output device turns off forcibly an output in case a falt is detected in the system 5 or 6. Then both devices 17 and 18 are switched by an OR gate 20. |
