This is where it all begins, the study of electricity and magnetism.
If you do not have an infinity (natural desire to learn more about) to the invisible realm of electricity and magnetism, it is unlikely that you will become a competent troubleshooter/technician/programmer in the world of industrial control systems. Industrial manufacturing is 99% electro-mechanical. The mechanical aspect of manufacturing, being visible, is more easily grasped by sheer observation. Being able to create in this realm requires a developed skill of three dimensional visualization or you could say, spatial reasoning.
It is assumed that you have a strong desire to understand and work in this environment, so we begin with a philosophical overview of electricity and magnetism.
Watch this lectures to verify that you have the fundemental grasp of these principles before you move on to PLCs.
This is a light introduction to Magnetism and Electricity. Just enough to give you a fundamental understanding of a circuit and enough to set the stage for understanding relays as well. There is an error in this lecture, Silver is considered a better conductor than Gold as well as copper.
The following lecture is an addditional lecture illustrating the principles of electricity.