Programmable Logic Controllers, commonly known as PLCs, are specialised industrial computers designed to control manufacturing processes, assembly lines, robotic devices, and virtually any activity that requires high-reliability control and ease of programming.
Unlike general-purpose computers, PLCs are built to withstand harsh industrial environments including extreme temperatures, humidity, electrical noise, and vibration. They run continuously in factories and plants around the world, making them one of the most critical components of modern automation infrastructure.
How Does a PLC Work?
A PLC operates on a simple but powerful cycle: it reads inputs from sensors and switches, executes a user-written program (logic), and then writes outputs to actuators such as motors, valves, and lights. This scan cycle repeats thousands of times per second, ensuring real-time control of industrial processes.
The key components of a PLC system include:
- CPU (Central Processing Unit): Executes the control program and manages communication.
- Input Modules: Receive signals from field devices like proximity sensors, push buttons, and temperature transmitters.
- Output Modules: Send control signals to actuators, motor drives, solenoid valves, and indicator lights.
- Power Supply: Provides regulated power to the PLC and its modules.
- Communication Ports: Enable connectivity with HMIs, SCADA systems, and other PLCs via protocols such as PROFINET, EtherNet/IP, and Modbus.
Where Are PLCs Used?
PLCs are found in virtually every industry:
- Manufacturing: Assembly lines, CNC machine control, packaging systems.
- Oil and Gas: Pipeline monitoring, refinery process control, safety shutdown systems.
- Water Treatment: Pump control, chemical dosing, filtration systems.
- Food and Beverage: Batch processing, quality control, conveyor systems.
- Pharmaceuticals: Clean room automation, tablet press control, serialisation.
- Building Automation: HVAC control, lighting systems, access control.
Why Should You Learn PLC Programming?
The demand for PLC engineers continues to grow as industries adopt more automation. Here are compelling reasons to start learning:
- High Demand: There is a global shortage of skilled automation engineers, particularly in the UK and Europe.
- Competitive Salaries: PLC programmers in the UK earn between GBP 35,000 and GBP 65,000, with senior roles exceeding GBP 80,000.
- Job Security: Automation is expanding, not contracting. Every new factory needs PLC engineers.
- Diverse Career Paths: From commissioning engineer to controls architect, PLC skills open doors to many roles.
- Hands-On Work: PLC engineering combines programming with real-world problem solving, ideal for those who enjoy practical work.
Getting Started
Begin with one of the two dominant PLC platforms: Siemens (TIA Portal) or Allen-Bradley (Studio 5000). Learn ladder logic first since it is the most widely used PLC programming language, and then expand into structured text and function block diagrams.
At EDWartens, our PLC training programmes provide hands-on experience with real industrial hardware and VR-based simulation, ensuring you are job-ready from day one.