please set up ladder logic. Placement of timers and counters is what i am struggling with.

Create a program that sorts and counts a product into three different chutes so that the boxes will contain 4,6 and 8 of the item being produced. The process takes product from a conveyor and sends it into chutes where it is boxed. The boxes will contain 4,6 or 8 of the product. Diverter gates control the product flow off of the conveyor. There are three light beam switches and two product diverter gates as shown below. The process starts with Gates 1 and 2 off. Once 8 products have been sent into the 8 pack chute diverter gate 2 will activate and let 6 products fall into the 6 pack chute. Diverter gate 1 will operate and 4 products will be sent into the 4 pack chute. Once the 4 pack is completed the process starts over. A watchdog timer monitors each of the packing processes and if any of the 4/6/8 packing processes require more than 20 seconds to complete the conveyor is stopped and a fault light is turned on. The system must be reset to continue operation. The total number of product packaged will be held in a counter until the reset button is pressed