This method will fill the box 100% about 95% of the time, and within 95% the remainder. I leave it to the student to set up a bit that anticipates the next broken bottle BEFORE IT ARRIVES AT THE SCRAP GATE. Then if the level = 150, a small bottle will not fit either. The logic for the above is if the next broken bottle is Large, then its volume = 15 and will not fit into a box with level of 145 already, since full = 155. Then for the Scrap Conveyor Motor, I set up parallel comparison instructions: IF COMBINED BOX FILL >= 145 AND NEXT BROKEN BOTTLE IS LARGE, OR IF COMBINED BOX FILL >=150 THEN START SCRAP CONVEYOR.

The extra factor of 10 is to eliminate fractional numbers in an Integer-only PLC. Then I used some math functions to calculate the Combined Box Fill = (15 x Large Count) + (10 x Small Count).

In my program, I used two counters, Small and Large Broken Bottle Counters. Does this give you an idea of what you need to do next? The Scrap Box will hold the equivalent of 15.5 Small Bottles. The bottles are two different sizes, with the Large Bottle being equal to 1.5 times the mass volume of the Small Bottles. You cannot control the Scrap Box Fill very accurately using only one Counter. Last night I borrowed a copy of the LogixPro disk and ran through the Bottle Line Simulation.

Bottle line simulator logixpro