| 摘要 |
PROBLEM TO BE SOLVED: To prevent erroneous output even when a plurality of communication option modules are individually hot-line detached and added. SOLUTION: A program logic controller 1 is provided with a communication option module 11 connected so as to be hot-swappable and a processor module 12(13) capable of communicating with the communication module 11. When the processor module 11 does not continuously receive a response from the communication option module 12(13) after outputting status information to the communication option module 12(13), it is recognized that the communication option module 12(13) has been detached. The communication option module 12(13) is added, and when the processor module 11 continuously receives the response from the communication option module 12(13) after outputting the status information to the communication option module 12(13), the processor module 11 sets output data validity to the status information to be output. COPYRIGHT: (C)2009,JPO&INPIT
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