PLC Programming
PLC stands for programmable logic controller. A PLC is used to control, regulate and monitor machines in industry. PLC programming refers to the programming of precisely these controllers, which enable the automation and control of complex industrial processes. In this article, you will gain a comprehensive insight into how PLCs work, their areas of application, the professional field of PLC programming and the various ways in which you can learn PLC programming.
How the programmable logic controller works
A programmable logic controller works according to a clearly structured principle that is divided into three main steps: input signal, programme execution and output signal.
This is illustrated by the example of a car wash:
In the first step, the PLC receives an input signal that is generated by various sensors or operating elements such as buttons and switches. These signals serve as input that the PLC processes.
Next, the PLC executes the pre-programmed control programme. This step contains the logic that determines which actions are to be carried out based on the input signals. Let’s take the example of a washing line: based on the selected washing programme, the PLC activates various steps of the washing process one after the other. This could be soaping, brushing or rinsing the vehicle.
Finally, the PLC issues an output signal. This signal controls various actuators such as water pumps and brush motors to perform the specified tasks. The water pumps spray water and detergent onto the vehicle, while the motors move the brushes into the correct position.
This sequence – from the input signal to programme execution to the output signal – is repeated continuously, allowing the machine to work reliably and efficiently. Thanks to this structured method of operation, a PLC can take over and optimise complex machine control systems in various branches of industry.
Structure of the programmable logic controller
A programmable logic controller has a modular structure and consists of several components that work together to enable the control and automation of machines.
Operating system: The operating system of the PLC is the basis on which the control programme is executed. It manages the PLC’s resources, executes the programmes and ensures communication between the various modules.
Interface: The control programme is uploaded to the PLC via the interface. This interface can take various forms, from serial interfaces to USB and Ethernet connections. Programmers can use it to install the programme and make updates as required.
Input/output units (I/O): The input/output units are the driver for the interaction of the PLC with the environment. Input units receive signals from sensors and control elements, while output units send signals to actuators in order to execute certain previously defined actions. These I/O units ensure that the PLC both receives information from the environment and issues commands to control the machines.
How is the programmable logic controller connected to the machines?
The programmable logic controller is connected to the machines via sensors and actuators to ensure smooth automated operation. Sensors act as input units for the PLC and record various signals from the environment, such as light barriers, buttons or temperature sensors. This information is transmitted to the PLC, which then makes decisions and generates control commands.
On the other side, actuators are connected to the output units of the PLC. They implement the commands calculated by the PLC, for example by switching on electric motors, opening or closing valves or controlling other mechanical and electrical components. This direct connection between the PLC, sensors and actuators enables the control system to react to changes in real time and carry out precise actions. This allows the desired operating sequence of the machines to be maintained.
Areas of application for PLC programming
PLC programming is used in various industrial areas in which complex machines and systems need to be efficiently controlled and monitored. PLC programming is particularly common in mechanical and plant engineering, where PLC programs are developed to automate and optimise production processes. In the automotive industry, PLC programmes are used innovatively to precisely control production lines and ensure the quality of the vehicles produced.
PLC programming is also crucial in the process industry. Here, complex systems in the chemical, pharmaceutical and food industries are operated with the help of PLC controllers in order to monitor and regulate production processes. In the energy sector, PLC programmes are used to control and monitor energy systems, for example in the regulation of waterworks or biogas plants.
Mechanical & plant engineering
Automotive industry
PLC programming has been a driving factor in the control and optimisation of production lines in the automotive industry for years. These systems automate and integrate processes such as assembly, painting, testing and packaging precisely and efficiently. They enable the control of robots, quality assurance of painting, automated testing and optimised material flow to reduce production costs and increase product quality.
Process industry
Energy systems
Manufacturer of programmable logic controllers
The world of programmable logic controllers is characterised by well-known suppliers. The following is a list of the best-known providers:
- Siemens
- Rockwell-Automation
- Schneider Electric
- ABB
- Bosch-Rexroth
- Beckhoff
- Delta-Elektronik
- Yokogawa
- Mitsubishi Electric
- Omron
The professional field of PLC programming
PLC programming is an exciting and varied professional field that attracts specialists from various technical disciplines. This professional field requires specialists who have in-depth knowledge of programming programmable logic controllers. PLC programmers are technical experts and play a key role in the development, implementation and maintenance of PLC programmes.
Which professional groups use PLC programming?
PLC programming is an indispensable component for a large number of professional groups in industry that deal with the automation and control of technical processes. The following professional groups and technical experts use PLC programming:
- Automation technicians
- Mechanical engineers
- Electrical engineers
- Mechatronics technician
- Building technicians
How do I become a PLC programmer?
The path to becoming a PLC programmer often leads via training or degree programmes in related technical fields such as computer science, mechanical engineering or electrical engineering. These disciplines provide a solid foundation for understanding automation technology and programmable logic controllers. During the course of study or training, basic knowledge of programming, control engineering and electronics is taught, which is essential for PLC programming.
For many prospective PLC programmers, practical experience is crucial. Through internships or projects during their studies, they can gain initial insights into the programming and operation of PLC programmes. This practical experience is often the key to establishing themselves in industry and developing their careers.
In addition to formal training programmes, targeted further education and training courses also offer an opportunity for further training in the field of PLC programming. These courses are often practice-orientated and teach specific skills that are directly applicable in industry. They cover advanced topics such as programming complex control sequences or integrating PLC programmes into larger automation solutions.
What does a PLC programmer earn?
The typical starting salary for PLC programmers is usually around 40,000 euros per year, but this also depends on the industry. With increasing experience, additional qualifications and specialised further training, the annual salary can rise to around 70,000 euros. Further training in specific areas of automation technology or obtaining additional certifications contribute significantly to improving career opportunities and increasing salary levels.
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Learn PLC programming
Learning PLC programming is a valuable skill for technically-minded individuals that is and will always be in demand in many industrial sectors. After successful training, you will be able to understand and develop complex control systems that make a significant contribution to the automation of industrial processes.
How long does it take to learn PLC programming?
The time it takes to learn PLC programming varies greatly depending on the learning method and individual learning speed. The basics can be grasped quickly, often within a few weeks, especially if structured learning content is available. However, an in-depth understanding and extensive expertise in PLC programming is developed over a longer period of time through continuous practical application and experience in real projects.
Where can I learn PLC programming?
PLC programming can be learnt during studies or training in the fields of computer science, mechanical engineering or electrical engineering, where basic knowledge is taught. In addition, specialised training courses offer practical training for professionals who want to expand their skills in automation technology. For people with a lot of discipline and perseverance, learning PLC programming is free, as extensive resources are available online and offline, including textbooks, video tutorials on YouTube and simulation software that ideally support independent learning and practical application options.
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