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Before PLCs took over industrial control panels, machines were controlled using physical relays, contactors, timers and miles of wiring.
It worked. Usually.
Understanding those older relay circuits remains surprisingly useful because modern ladder logic was built around the same ideas. Contacts become instructions, relay coils become outputs, and the tangled control panel eventually moves onto a PLC screen.
The Udemy course Relay Logic – The Foundations of Ladder Logic and PLCs explains that connection from the beginning. I believe it is a very good introductory course for apprentices, students and future automation engineers who want to understand where ladder logic actually came from.
[Relay Logic – The Foundations of Ladder Logic and PLCs]
What Does the Course Cover?
Created by Stephen Raymond, the course currently contains seven sections, 39 lectures and almost six hours of video. Udemy lists it as a Highest Rated course with a 4.7 rating, more than 60 reviews and over 1,200 enrolled students. It was last updated in March 2026.
The curriculum covers:
- Relay-logic fundamentals
- Reading electrical drawings
- Normally open and normally closed contacts
- Relays and contactors
- Limit switches
- On-delay and off-delay timers
- Motors and indicator lamps
- Latching circuits
- Electrical interlocks
- Forward and reverse motor control
- Traffic-light sequences
- Gate-control systems
These are the building blocks found inside countless industrial control circuits. Learning them makes PLC ladder diagrams feel less like mysterious symbols and more like electrical circuits moved onto a computer.
Real Components, Not Only Slides
One of the course’s better features is its use of physical demonstrations.
The instructor shows components such as contactors, relays, switches, timers and motors, explaining how they operate and how they appear on electrical drawings. The devices are also demonstrated on a test rig rather than existing only as tidy symbols in a presentation.
That matters. A learner may understand a relay coil on paper yet still feel completely lost when standing in front of a real control cabinet.
Seeing both sides helps connect the dots.
Building Circuits With EKTS
Students use EKTS electrical control simulation software to create and test relay circuits on a Windows computer.
The software exercises include basic circuits, latching, interlocking, timers, reversing motors, traffic lights and an automatic gate system.
Simulation is especially useful here because relay logic rarely sinks in through passive watching. You need to place the contacts, wire the coil, press the button and discover why absolutely nothing happened.
Then you fix it. That is the useful part.
Five Practical Projects
The course includes five main projects, followed by a bonus-project section.
Each project provides a specification and test criteria. Students are expected to build their own solution before watching the instructor’s demonstration. The course makes an important point: when the circuit meets the required criteria, there may be several valid ways to design it.
That approach encourages actual problem-solving rather than copying finished diagrams line by line.
Who Is This Course For?
The course is suitable for:
- Engineering apprentices
- Electrical students
- Beginner automation technicians
- Aspiring controls engineers
- Electricians moving toward PLC work
- Anyone struggling with ladder-logic fundamentals
No previous experience is required, although students need a Windows computer capable of running EKTS.
Are There Any Downsides?
This is a foundation course, not complete PLC-programming training.
It does not provide detailed instruction in Siemens TIA Portal, Rockwell Studio 5000 or another industrial PLC environment. Topics such as analogue signals, communication networks, HMI programming and structured PLC projects are outside its main scope.
That is not necessarily a weakness. The course concentrates on the fundamentals and does not pretend that six hours will turn a complete beginner into a senior controls engineer.
Final Verdict
Relay Logic – The Foundations of Ladder Logic and PLCs is a very good starting point for understanding industrial control circuits.
Its combination of physical components, electrical diagrams, simulation exercises and practical projects provides a useful bridge between traditional relay panels and modern PLC ladder logic.
Learn the relay circuit first, and the PLC version suddenly makes far more sense.
Check the current course price and availability here: