What is a Controller?
A controller is a device or software component that operates a process, system or machine based on measurement data, configured parameters and logic.
Controllers are the heart of industrial automation: they make decisions, drive Actuators, and ensure the correct operation of machines and processes.
In practice, controllers can be physical (such as a PLC) or software-based (such as a PID control loop or SCADA script).
🧠 What does a controller do?
- Reads measurement values from sensors (e.g. temperature, pressure, position)
- Compares them against configured targets or setpoints
- Makes decisions based on logic, rules or computational models
- Drives actuators such as valves, motors or alarm systems
- Uses feedback to stabilise or optimise the process
🔧 Types of controllers
| Type | Explanation |
|---|---|
| PID controller | Regulates process variables such as temperature or pressure |
| PLC (Programmable Logic Controller) | Industrial digital controller for discrete logic |
| Motion controller | Driving servomotors or multiple axes |
| Embedded controller | Built into devices, often microcontroller-based |
| PAC (Programmable Automation Controller) | More advanced version of a PLC, with greater compute capability |
🏭 Examples in practice
- A PLC coordinating a packaging line
- A PID controller regulating the temperature in an oven
- A motion controller synchronising 3 axes of a robot arm
- An HVAC controller driving ventilation and heating
- An embedded controller in a washing machine or pump
✅ Benefits of controllers
- Automating processes without human intervention
- Greater precision, speed and repeatability
- Real-time control with feedback
- Easy integration with SCADA, HMI and MES
- Robustness and reliability in industrial environments
📌 In summary
A controller drives processes by continuously making decisions based on measurement data and logic — and is therefore the core of every automated installation.