The 10 Most Common Mistakes When Learning PLC

Learning PLC is an important step for anyone aiming for a career in industrial automation. Yet many learners slow their own progress by falling into common traps — choosing the wrong method, focusing only on theory, skipping hands-on practice, or trying to write programs without understanding industrial logic. Getting the approach right lets you develop faster, build better projects, and establish a solid technical foundation for the industry.

1. Thinking PLC Is Just About Writing Code

The most common first mistake is assuming that learning PLC means learning a piece of software. PLC is actually the intersection of electrical, electronic, mechanical, automation, and programming knowledge. Writing Ladder code alone is not enough to run a motor — you also need to know how the motor is wired, how the contactor works, and when the sensor sends a signal. Hardware, software, and automation logic must be developed together.

2. Starting Without Basic Electrical Knowledge

PLC systems work with electrically controlled machines. Those who have gaps in relay logic, contactor use, motor control, sensor wiring, and control circuits will hit serious obstacles later on. Electrical control fundamentals should be developed in parallel with PLC learning, not set aside for later.

3. Trying to Memorise Commands

Beginners often focus on how to write a command rather than why that command is used and what system need it addresses. Knowing the Timer instruction is useful, but being able to answer "In which production scenario is this timing needed?" is far more valuable. The goal is to understand logic, not to memorise syntax.

4. Relying Solely on Video Tutorials

Training videos are useful, but not sufficient on their own. PLC is learned by doing, not by watching. After each new topic, completing a small hands-on exercise makes the knowledge stick and ensures it can be recalled when it matters.

5. Having No Access to Real PLC Hardware

Simulation is useful for getting started, but it cannot replace field experience. Wiring a real PLC, loading a program, encountering unexpected errors, and troubleshooting them teaches you how PLC behaves in an industrial environment. Practising with real equipment as much as possible is therefore important.

6. Finishing Training Without Building a Project

Many people study a lot of topics but never build a complete system from scratch — and as a result the knowledge does not stick. At beginner level, start/stop motor control; at intermediate level, a conveyor system or sensor-controlled production line; at advanced level, an HMI-controlled machine. Without project work, it is very hard to develop genuine technical competence.

7. Trying to Learn Too Many PLC Brands at Once

The market includes Siemens, Mitsubishi, Allen Bradley, Omron, and Schneider, among others. A common beginner mistake is trying to learn all of them simultaneously, which makes the learning path unnecessarily complex. Starting with one widely used platform — for example Siemens TIA Portal and S7-1200 — is far more effective.

8. Being Afraid of Errors

Real automation professionals develop by solving faults. When a program does not run, a wiring error occurs, or the system does not respond, understanding why and working through it systematically is an inseparable part of learning. Every error is an opportunity to practise asking "Why didn’t this signal arrive?" and "Where did the program stop?"

9. Neglecting HMI and Communication Topics

Modern PLC systems do not operate in isolation. HMI screens, SCADA systems, and industrial communication protocols are core components of today’s automation environments. Knowing only PLC programming may not be enough for many real-world projects. After mastering PLC fundamentals, moving on to HMI, SCADA, and communication protocols is strongly recommended.

10. Progressing Without Understanding Industry Logic

Focusing only on the programming side is not sufficient for PLC expertise. Understanding how a machine works, designing a production sequence, accounting for safety requirements, and evaluating system efficiency are the core skills of a real automation professional. Trying to understand the machine and the production process should begin alongside programming — ideally even earlier.

The Right Learning Path

A successful route moves from electrical fundamentals through PLC working principles, Ladder programming, sensor and motor applications, HMI, communication systems, and finally real industrial projects. Following this order both shortens the learning time and builds a lasting technical foundation for the industry.