ST中下降沿 的FB塊 是F_TRIG   需要實例化才能使用
復刻梯形圖:
                      聲明區:  F_按鈕下降沿:ARRAY[1..3] OF F_TRIG; 3個實例化對象
                      程序區:  F_按鈕下降沿[1](CLK:= M0, Q=> );      // () 內為FB塊的管腳
                                      F_按鈕下降沿[2](CLK:= M1, Q=> );
                                      F_按鈕下降沿[3](CLK:= M2, Q=> );
                                     IF   F_按鈕下降沿[1].Q  OR  F_按鈕下降沿[2].Q  OR  F_按鈕下降沿[3].Q   THEN 
                                           M10:=FALSE;
                                     END_IF