I'm trying to write the logic for the following process:
This is a single conveyor system that has 4 camera stations in sequential order used for inspection. Each station gives a result for each part that passes under it. The conveyor runs at a constant speed but the parts are loaded at different intervals or timing so the spacing will always vary.
When the the part reaches the end of the conveyor I have to pick the the part and place it according to the result of each inspection station. I might have 6 parts or 2 parts on the conveyor at a time and at different locations.

I'm familiar with bit shift command but that only works for a controlled index. Can someone provide me a correct solution in ladder logic for this application? I'm using Unilogic PLC.

 

Is there always a decent gap between parts? If so, look into building a FIFO (First In First Out) array.

Unfortunately, I'm not familiar with Unilogics, so I can't help you build it on that platform.