CODESYS Basics | What is CODESYS and Why is it Important?

Master CODESYS fundamentals. Examine components and applications.
Listen to this article

At RealPars, our goal is to inform automation and controls engineers about exciting new technologies in industrial automation and educate them about how to use new and existing technologies to level up their careers. Today, we will introduce you to CODESYS, one of the most exciting technologies in the industrial automation space in the last few years.

Over the next ten minutes, you will learn what CODESYS is, why CODESYS is important, and how you can invest in your career by learning CODESYS starting today.

Let’s get started by talking about what CODESYS is.

What is CODESYS?

When people talk about CODESYS, which is short for COntrols DEvelopment System, they are really talking about two related pieces of software.


The first piece of software is an Integrated Development Environment known as the CODESYS Development System.

Programmers and controls engineers can use the CODESYS Development System to write control applications using the IEC 61131-3 programming languages and to create visualizations for those control applications.

In case you are not familiar with it, the IEC 61131-3 standard is an international standard that defines the programming languages used to program PLCs.

The programming languages defined in this standard include Ladder Diagram, Function Block Diagram, Structured Text, Instruction List, and Sequential Function Chart.


You can learn more about the IEC 61131-3 programming languages in the RealPars post What are the Most Popular PLC Programming Languages?

The second piece of software is a runtime. The runtime executes applications developed in the CODESYS Development System and serves the visualizations for those applications to clients.

The CODESYS runtime is typically installed on a PLC but can be installed on any intelligent device that meets the runtime’s minimum requirements, such as a Raspberry Pi.

CODESYS runtime

When the runtime is installed on a device, we say that the device is CODESYS-compatible since the device can execute CODESYS applications.

This is a really exciting feature of CODESYS because it allows programmers and controls engineers to develop truly hardware-independent applications.

Let’s take a closer look at the advantages of hardware-independent applications.

Why is CODESYS important?

As you may have picked up from the previous section, 3S-Smart Software Solutions, the company behind CODESYS, is a software company. They develop the CODESYS Development System and runtime and generate revenue by licensing the runtime to PLC manufacturers. 3S does not manufacture any hardware. It is also good for you to know that they have rebranded to CODESYS sicen 2020. That means the company is called CODESYS instead of 3S-Smart Software Solutions.

This is very different from traditional automation companies like Siemens and Rockwell Automation which develop a proprietary development system and runtime and manufacture their own hardware.

Advantages for PLC manufacturers

Although this may seem like a small difference, it introduces some advantages for PLC manufacturers and PLC programmers.

By partnering with CODESYS, PLC manufacturers can focus on their core competency of building innovative PLC hardware and leave the software development to CODESYS, who specialize in developing control software.

This reduces cost for the manufacturer to develop PLC product lines. Those reduced costs lead to higher profits for the manufacturer and some of the savings can be passed on to OEMs and end users.

CODESYS Advantages for PLC Manufacturers

Advantages for PLC programmers

By learning CODESYS, PLC programmers can learn how to use the CODESYS Development System and use those skills to develop control applications for any CODESYS-compatible PLC.

This makes a programmer’s PLC programming skills more transferable and reduces the need for retraining when moving from one job to the next.

CODESYS Advantages for PLC Programmers

Benefits of feedback to 3S

Finally, since so many individuals and companies are using CODESYS, a lot of feedback is given to 3S which allows them to rapidly introduce and test new features, and discover and fix bugs in the software.

This is one of the reasons why the CODESYS Development System is so advanced with innovative features like Object Oriented Industrial Programming included.

Potential of CODESYS in the PLC market

As Gary Pratt, the author of the Book of CODESYS, describes it, the PLC runtime market today is very like the smartphone operating system market of the early 2000s. When smartphones were first introduced, every company developed a proprietary operating system for their smartphones.

Eventually, Google introduced the Android operating system which was a hardware-independent operating system. Some smartphone manufacturers standardized on Android and some stuck with their proprietary operating systems.

Over time, companies that adopted Android like Samsung and Huawei thrived, and those that didn’t like Nokia, Motorola, and Blackberry died.

There are many people who believe that CODESYS is the Android of PLC runtimes. For this reason, an investment in learning CODESYS now will pay dividends in the future since the market share of CODESYS will only increase with time.

PLC runtime vs. smartphone operating system

Is CODESYS popular?

Although we have spent a lot of time talking about how important CODESYS is to the future of industrial automation, we want to highlight that CODESYS is a very popular technology being used in industry right now.

From 2010 to 2018, 3S has grown consistently by an average of 15% which highlights the fact that CODESYS adoption is growing. In fact, in 2011 a survey found that the market share of PLCs based on CODESYS in Europe was 35% which was equal to the market share of Siemens PLCs.

Today, there are over 500 manufacturers producing over 1000 CODESYS-compatible devices and that number will only grow from here.

CODESYS market share


In this article, we have introduced you to CODESYS, a fast-growing and exciting technology in industrial automation. We have explained what CODESYS is, why it is important, and how popular CODESYS is with PLC manufacturers and end users.

One of the best things about CODESYS is that you can download and use the CODESYS Development System for free.

You can also run a trial of the CODESYS Runtime on your laptop for a 2-hour period to test the applications that you develop in the CODESYS Development System. This means that you can start learning PLC programming with CODESYS for free, without buying any software licenses or hardware.

If you are interested in learning more about PLC programming with CODESYS, you can check out our course CODESYS 1: Introduction to PLC Programming. This course gives you a detailed introduction to CODESYS and shows you how to write and test your first CODESYS application.

Join the Top 1% of Automation Engineers

Try for Free

Learn from
industry experts

Start your learning journey today!

with a free 7-day trial, then $25/month
Start Free Trial Now