| 摘要 |
PROBLEM TO BE SOLVED: To simplify operation and to surely eliminate erroneous operation. SOLUTION: In an erroneous input preventing device for a preset counter, a pair of a light emitting element 22 and a light receiving element 23 receiving the signal from the element 22 constitutes each photoelectric switch, plural photoelectric switches are arranged on a switch fixing board 4, processing functions are made to correspond to these photoelectric switches respectively and each of the functions of these photoelectric switches which has processing functions except for stopping and resetting requiring urgency are prohibited form operating unless a shift switch is pressed. Thus, an operation switch can be miniaturized and its weight can be reduced. Since an operator executes operation with both of his/her hands except for emergency, erroneous pressing of the operation switch is reduced and it is eliminated to mistake a set value because of wrongly operating a neighboring operation switch and to wrongly input a reset or start switch though the flow of a fluid must be stopped originally.
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