| 摘要 |
PURPOSE:To prevent the breakdown in a bus control system when a specific master unit has a fault by releasing a bus and stopping the control after detecting that the bus using time in a multi-master system exceeds the prescribed value for said multi-master system. CONSTITUTION:In case an access is given mistakenly to an address outside the packaging range of a memory 8, a data fixing signal RDY is not delivered from the memory 8 and a BSY signal line 16 is kept at a low level. If the BSY signal is supplied yet when a prescribed period of time set by a monostable multivibrator within a bus monitor part 19 of a PiD control unit 4 elapses, an ALARM signal is outputted and informed to a main control part 21 via a signal line 23. At the same time, an interruption is applied to another master unit via an iRT4 and a bus 17. Thus the own fault is informed to another master unit. Thus the breakdown in system is prevented.
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