Yes the logic looks correct. You might want to add to some of the comments, specially about the meaning of LOW and HIGh and how each of the IP4 and IP5 sensors work on each rung (copy and paste lines from the old comments).
Sorry, my Email has stopped working today, temporarily I hope.
Notice that the FFL will not accept a bit address as a Source. It must be a full word address (all 16 bits).
B3:1/0: (PART ASSEMBLY: 1 = Not Correct, 0 = Correct) [Actually you are using the entire B3:1 word, all 16 bits from B3 :1/0 up to B3:1/15. The reason to use a word instead of a single bit is that the FFU and FFL instructions move and shift entire words (16-bit groups). Using only a single bit in the FIFO FFL Source address will cause an error. The correct address in this comment should be simply » B3 :1 », or maybe « B3 :1 word ».