| 摘要 |
PURPOSE:To utilize an external input terminal effectively by allowing a ladder diagram input type programmable controller to operate corresponding to an instantaneous power failure only with an auxiliary relay input instruction. CONSTITUTION:A basic programmable controller unit 1 obtains DC power from commercial electric power supplied from a power terminal 4 by the intervention of a transformer 5, rectifying circuit 6, etc., and also supplies the output of the rectifying circuit 6 to a momentary power failure circuit 8 to detect a momentary power failure, thereby initiating an interruption for the power failure to a microprocessor 9. In this case, one of external input terminals of an AC unit 2 for extension is not used exclusively for the power failure, and an area for storing the output signal of an auxiliary relay for power failure detection is provided in an auxiliary relay output area in RAM11. Consequently, if a momentary power failure occurs during program execution, the auxiliary relay contact is made to interrupt the execution and a keep relay is prevented from being reset. |
