The PLC troubleshooting demo video by http://www.bin95.com helps with student PLC projects by explaining the, limit switch, PLC wiring and how PLC works. With this demo of DVD 9a of the Industrial Electrical Training Video course, you see PLC troubleshooting of an optical isolator and related I/O technology. Note, this is just a short, low resolution demo of the 10 DVD electrical course. http://www.youtube.com/watch?v=2AzAvBG5-yA
For instructor based PLC Training, see https://www.youtube.com/watch?v=Bw-m9gT7Nh4