conveyor Rejection System

I am beginner using plc s7 300.
I need to design a conveyor Rejection System for bottles if the gap less then 80% reject the bottle before and after .
Speed is 150 bottles per minute, the rejection pulse should be made after five bottles. I will appreciate your hints.
Thanks.

http://accautomation.ca/plc-programming-example-shift-register-conveyor-reject/

https://www.youtube.com/watch?v=K1j6HvNF-5s

Take a look at the above thread. It should help you out.

Regards,

Thank you for your response but,
that not clear to me because this example not using siemens s7-300

The example above is to get the idea of how shift registers work. It does not matter what controller you are using because the concept is the same.
You have inputs to the shift register to detect the product.
You have clock bits to determine the speed of the conveyor.
Bits shift in the register at a clock input speed. Inputs turn the bits on/off in that same register.

Regards,