The course notes do not contain the relevant information needed to answer this question - they only contain a brief overview of how LADSIM works.
There is no guidance on how to analyse and solve a problem - no examples of any methodological approaches.
The explanation of the code available is too concise and there are relatively few examples of the code.
Although there is a list of textbooks, the notes do not contain directed reading.
One of the online books,
Bolton, W. (2009) Programmable Logic Controllers, explains how to implement a program to keep track of items an a conveyor and use a sensor to detect faulty items and reject them using a piston.
The information is in Chapter 11: Shift Registers.
I developed the basics of this before I found it in the textbook; that boosted my confidence!
If you're attempting to use Bit Shift Registers, you obviously need to know how they work with your simulation software.
Again, there is relatively little useful information in the course notes and there is no software manual!
Luckily, the information was available online thanks to students:
http://www.freestudy.co.uk/plc/bytronics%20work%20sheets.pdf
However, even these notes don't explain that with LADSIM in the BIT SHIFT REGISTER options, you click on the option "Outputs" to successfully implement their example code.
To complete the last part of this exercise, I needed to design:
1. A method of differentiating between assembled and non-assembled items.
2. A method of inputing this data into a Bit Shift Register.
3. A method for shifting this data along the register for each new item.
4. Using this data to reject non-assembled items using a piston.
Now that I know how Bit Shift Registers work in LADSIM, I can write and test the code.
The course notes are too concise and there is no manual for the software - a relatively straightforward exercise was made needlessly harder!