| 摘要 |
PROBLEM TO BE SOLVED: To provide a programmable logic controller (PLC) for making a unit attachable/detachable through tool-less online and reducing a processing load on a system program side in determining that the unit is detached. SOLUTION: If an abnormal response is detected when a CPU unit (2) accesses a functional unit through either one of connectors (13a-13d), the PLC refers to stored content in an inner register (12) related to the accessed connector, and if it is determined that the stored content shows 'a unit detached state', the PLC executes processing required to detach the unit (2). COPYRIGHT: (C)2008,JPO&INPIT
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