| 摘要 |
PURPOSE:To protect a circuit by storing the operation stage of a controlled system set before a holding state into a memory in addition to a specific code setting the controlled system in an operating state set before the holding state or in an initial state with collation of the codes when the controlled system is restored from the holding state. CONSTITUTION:When the drop of voltage is detected by a voltage detecting circuit 17, a CPU 14 is stopped and set in a holding state and also writes a specific collation code in a prescribed address of a RAM 19 to store the operating state of a slave device 10. If the address 1-8 are assigned in the RAM 19 for the collation codes, '1' is written into all address at the collation codes. When power is recovered and detected by the circuit 17, the CPU 14 restarts its operation and reads the collation codes out of the RAM 19 to decide whether all collation codes are kept at '1' or not. If the contents of the collation codes are coincident with each other, it is decided that the contents of the RAM 19 are normal. Thus the device 10 is restored to the state set right before the holding state. Meanwhile the CPU 14 is initialized if the contents of the collation codes are not coincident with each other. |
