sngX1 := UINT_TO_REAL (uintX1);
sngX2 := UINT_TO_REAL (uintX2);
sngY1 := UINT_TO_REAL (uintY1);
sngY2 := UINT_TO_REAL (uintY2);
sngX := UINT_TO_REAL (uintX)*EXPT (10.0, uintDecPtDiff);

IF sngX <= sngX1 THEN
    uintY := REAL_TO_UINT (sngY1);
ELSIF sngX >= sngX2 THEN
    uintY := REAL_TO_UINT (sngY2);
ELSE
    uintY := REAL_TO_UINT (sngY1+(sngY2-sngY1)/(sngX2-sngX1)*(sngX-sngX1));
END_IF;

我沒用過歐姆龍的，不過這個看起來也不難理解吧。
sngX1 := UINT_TO_REAL (uintX1);這個是數據類型轉換，整型轉換成浮點型，
IF sngX <= sngX1 THEN
    uintY := REAL_TO_UINT (sngY1);
ELSIF sngX >= sngX2 THEN
    uintY := REAL_TO_UINT (sngY2);
比較，轉換，賦值。
ELSE
    uintY := REAL_TO_UINT (sngY1+(sngY2-sngY1)/(sngX2-sngX1)*(sngX-sngX1));
END_IF;
計算，賦值。