| 摘要 |
PROBLEM TO BE SOLVED: To provide a PLC unit, capable of swiftly and accurately detecting damaged data in a memory and, when memory abnormality of damaged data is detected, of automatically restoring it, while continuing the operation of the system. SOLUTION: The programmable controller unit comprises a user memory 14 for storing a user program which is read at calculation processing, and a backup memory 15 for storing the same content data as that in the user program stored in the user memory. Also, the programmable controller unit compares the user data stored in the user memory 14 and that in the backup memory 15, during a cyclic execution and determines whether there is a memory abnormality. When memory abnormality is detected, data in a part of the detected memory abnormality is restored by data, at the corresponding part in the backup memory; and the cyclic execution is continued, even after this. As a result, damaged data of the memory can be detected swiftly and accurately, and when memory abnormality of damaged data is detected, it can be automatically restored, while continuing the operation of the PLC. COPYRIGHT: (C)2004,JPO&NCIPI
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