I got two items, item A & item B, they got different physical sizes. Item B is long than item A. In order to distinguish the items from each other, we can record how long the signal from the photocell stays high. I need to make a program this and counts the number of each type. It is problem 10.6 from the book PLC - Dag H.Hansen. Does somebody know how to make a ladder logic program from this problem?