| 摘要 |
PURPOSE:To eliminate the possibility that malfunction of a processor causes an accident, by completely disconnecting an external objective to be controlled from the control of the processor when the processor malfunctions. CONSTITUTION:If a program causes a runaway when an interruption request signal arrives at a microprocessor MP1, command data are not read out of a memory 4 normally. At this time, a command data generating circuit 2 generates and holds data which correspond to said interruption request signal, so a comparing circuit 3 does not detect data coincidence and a timer circuit 6 outputs a fail signal. This output places a switching circuit 8 in offline mode, outputting a reset signal and an offline signal. This reset signal stops the MP1 and an IF circuit 9 outputs no control signal, disconnecting an objective to be controlled from the MP1. Further, the objective operates with irreducible necessary functions by the input of the offline signal. |
