CODESYS 4 Version 1.0.0.0 was released on September 24, 2026. This article explains the features of CODESYS 4, its connectivity, installation methods for Windows and Linux, and basic operations.

Now, let’s enjoy FA!

CODESYS 4

CODESYS 4 Version 1.0.0.0 was released on September 24, 2026. It is a new programming system offered alongside the conventional CODESYS Development System 3.

As before, it complies with IEC 61131-3, allowing programming using Structured Text (ST) and Ladder Diagram (LD), but its internal architecture has undergone significant changes.

The user interface runs in a web browser, and projects are stored on the hard drive as folder structures composed of text files. Furthermore, in addition to GUI operations, a command-line interface is now available.

CODESYS 4 refreshes the development environment itself while maintaining the proven foundation. The compiler is identical to CODESYS 3, and the libraries used are also the same. Additionally, there are no changes to the runtime system running on the controller.

Therefore, code compiled with CODESYS 4 can be executed directly on any controller capable of running code created with CODESYS 3.

CODESYS 4 is not a replacement for CODESYS 3.

Both CODESYS 3 and CODESYS 4 will continue to be developed and maintained in parallel. Users can decide for themselves whether and when to adopt CODESYS 4 for their projects. It is also possible to use both in combination.

For example, you can perform development in CODESYS 4 while conducting actual machine startup and commissioning using CODESYS Development System 3. Note that in the initial version, available features are intentionally limited.

As of September 24, 2026, CODESYS 4 Version 1.0.0.0 supports practical work primarily for the following two use cases:

Library development using Structured Text (ST) and Ladder Logic (LD)
Automated builds, supporting build processes via “CI/CD”
Small-scale device projects using Modbus TCP

What remains unchanged?

First, let’s look at the most important point, which also answers the most frequently asked question: Your existing assets and hardware can be used as they are. The compiler, libraries, and runtime remain identical to previous versions.

CODESYS 4 uses the same CODESYS compiler and the same libraries as CODESYS Development System 3. In addition, the runtime system operating on the controller is identical. Therefore, the hardware investments, libraries, and IEC 61131-3 knowledge and expertise you have accumulated can be utilized directly.

Programming

Programming continues to follow IEC 61131-3 standards.

Structured Text (ST) and Ladder Diagram (LD) are available right from the initial version.

The Ladder Diagram editor has been redesigned for CODESYS 4, based on the familiar graphical editor used in CODESYS 3.

Therefore, there is no need to learn high-level programming languages such as C++ or C# to use CODESYS 4.

Bidirectional compatibility for library projects

Regarding library projects, there is bidirectional compatibility between CODESYS 3 and CODESYS 4. A library project saved in file-based format in CODESYS 3 can be opened in CODESYS 4, and vice versa.

In addition, libraries compiled in CODESYS 4 (Compiled Library) can be incorporated into projects in both CODESYS 3 and CODESYS 4 environments.

また、CODESYS 4でコンパイルしたライブラリ（Compiled Library）は、CODESYS 3、CODESYS 4のどちらの環境のプロジェクトにも組み込むことができます。

Converting device projects

On the other hand, device projects require conversion. Currently, device projects cannot be directly opened between CODESYS 3 and CODESYS 4.

Provision of a conversion tool is planned, but it is not yet included in Version 1.0.0.0.

Parallel use of CODESYS 3 and CODESYS 4

CODESYS 3 and CODESYS 4 are used and operated in parallel. CODESYS 3 will also continue to be developed and maintained moving forward. CODESYS 3 is a development environment used by over 300,000 users with a track record spanning over 20 years.

There are currently no plans to end CODESYS 3, and no specific date has been set for CODESYS 4 to completely replace CODESYS 3.

Is CODESYS 4 suitable for your project?

Let’s see whether you should use CODESYS 4 based on three use cases below.

If you are developing libraries in Structured Text

The initial version of CODESYS 4 is highly suitable for these applications.

Projects are structured as text files, with dependencies also described within the files. Additionally, the library build process can be automated. The generated Compiled Libraries (compiled libraries) can be used in both CODESYS 3 and CODESYS 4.

If you are building small machines or test benches

Target systems are those with a relatively small number of digital/analog I/O points connected via Modbus TCP. The control logic can be created in:

Structured Text (ST)
Ladder Diagram (LD)

Inputs and outputs can be configured on the Modbus configurator.

If you are using Linux or ARM hardware

The CODESYS 4 development environment itself runs directly on Linux x64 and Linux ARM64 without using virtual machines. Therefore, if you are already running Software PLCs or Virtual Controllers on Linux, you can start development directly on the same Linux platform.

What if none of these apply to you?

In that case, CODESYS 3 remains the primary development tool for production work at present.

CODESYS 4 is available for free until the end of 2028, allowing early exposure to the new concepts and mechanisms that will serve as the foundation for future functional enhancements. Also, if you are already developing full-scale PLC applications in CODESYS 3 and using additional tools included in the Professional Developer Edition—such as CODESYS Git or CODESYS MCP Server—CODESYS 4 is provided as an additional professional development tool within that license package.

Library build process

Before getting started, let’s review two terms.

Version control with Git is a repository mechanism that allows tracking all code changes by “when,” “by whom,” and “what changes were made.”
A pipeline is a series of automated tasks triggered on the server by specific events. You can automatically compile and check code without manually launching programs.

Step 01: Development

Libraries are created using the Structured Text editor. The editor provides features such as syntax highlighting, auto-completion, and tooltips when hovering mouse cursor over code. As before, you can also continue development using CODESYS 3.

Step 02: Save and compare

Check in the project directory to Git. Since all files are stored as text files, running a diff allows you to precisely check which lines were modified. Parallel changes made by multiple developers or team code reviews can be managed using standard Git tools already used by your internal IT department.

Step 03: Record dependencies

Libraries.json records the libraries used in the project. For example, you can specify a range of usable versions such as 3.5.*.

Meanwhile, Libraries.lock.json records the exact versions of the selected libraries and their checksums. Both of these files are saved inside the project.

This enables computers in the CI/CD pipeline to build using the exact same library versions as the developer’s workstation.

Step 04: Automatic build after approval

Assign a version number to the release version in the repository. Adding this mark, a Git tag, serves as the trigger to start the pipeline.

The server fetches the tagged version and executes c4 library save-compiled.

Since compilation runs headless without a user interface, no operator needs to sit in front of the computer to monitor the process.

Step 05: Distribute and integrate into projects

The output generated by the build is a Compiled Library with the .compiled-library extension.

Source code is not included in this file. The generated library can be signed, stored with a version number, and integrated into CODESYS 3 and CODESYS 4 projects.

When pipeline processing succeeds or fails, notifications can be sent via email or chat messaging.

Two ways to transition to a pipeline

Scenario A: Starting with small steps

For library development, verification, and testing, continue using CODESYS 3 as before. Use CODESYS 4 solely for automated build processes. This approach requires no changes to your daily development workflow.

In other words, you can start with:

Development & Testing: CODESYS 3
Automated Build: CODESYS 4

setup.

Scenario B: Full migration to CODESYS 4

In this approach, libraries themselves are developed directly in CODESYS 4. However, automated module testing is not yet available in Version 1.0.0.0.

Instead, test applications are used for functional testing. This method involves preparing a separate CODESYS 4 project that incorporates the target library and manually running it to verify operation.

Note that CODESYS Test Manager currently still requires a virtual machine running CODESYS 3.

Small device projects: Development flow

Step 01: Create a project

First, create a workspace and then create a device project inside it. Next, select the target CODESYS Control SL Runtime System.

For example, select a runtime like CODESYS Control Win V3 x64 and specify the programming language to use.

Step 02: Programming

Control logic is created using:

Structured Text (ST)
Ladder Diagram (LD)

and other supported options.

The Ladder Editor is provided with basic offline features in version 0.1, with further functional expansion planned in future updates.

Step 03: Connect I/O

Add an Ethernet node to the project tree, and under it add:

Modbus TCP Client
Modbus TCP Server

or a Modbus TCP Server Device.

Afterward, create communication channels and map each input/output to variables in the program.

In short, the flow is:

Ethernet configuration

→ Modbus TCP configuration

→ Channel creation

→ Assignment to I/O variables

Step 04: Load and monitor

Load the created application into the controller. You can then monitor variable states directly in the editor or from the Watchlist.

Features not yet available in Version 1.0.0.0

In Version 1.0.0.0, online changes to running programs are not supported. Setting breakpoints and forcing variable values (Force) are also not supported yet.

Furthermore, live signal flow display in Ladder Diagram (LD) is currently unavailable. Therefore, for traditional machine startup and commissioning, CODESYS 3 remains the suitable tool.

Security

CODESYS 4 adopts a security-conscious architecture from the ground up. Specifically, authentication, request rate limiting, and process isolation are built into system design.

In server mode, an independent OS process is assigned to each session. Thus, even if a session crashes, it does not affect other sessions. User permissions are managed using the Linux user management system.

In addition, communication channels between the user interface and background processes are protected against CSRF (Cross-Site Request Forgery).

In hosted environments, browser communication is encrypted via TLS.

ホスティング環境では、ブラウザからの通信もTLSによって暗号化されます。

CODESYS 4 Execution / Deployment Patterns

First, to clarify, “web-based” refers to the user interface technology model. CODESYS 4 is neither a cloud service nor subscription-only software.

Where the software runs can be decided entirely by the user. All deployment variants can operate completely within your internal network.

Note that Linux is required for server operation and running directly on devices.

Single-user mode on Windows

Supports Windows x64 and installs from an .exe file. CODESYS 4 launches in a dedicated window, so there is no need to separately launch a browser.

Single-user mode on Linux

Supports Linux x64 and Linux ARM64, installing as a Debian package. Running a single command launches a local session, which you can access via a local web browser.

Shared server for teams

Supports Linux x64 and Linux ARM64. c4-server manages logins and sessions. User management utilizes local Linux users/groups and can integrate with LDAP or other directory services via PAM.

Each user session runs as an independent process. The server can also run directly on the control system itself.

Headless automation without user interface

Supported OS versions:

Windows x64
Linux x64
Linux ARM64

The command-line tool c4 launches to perform specified tasks and exits upon completion. Envisioned usage includes:

Manual execution
Script execution
Scheduled jobs
CI/CD pipelines

and similar workflows.

In the initial version, no separate license is required for computers executing CI/CD pipelines.

Supported Controllers

In Version 1.0.0.0, only CODESYS Control SL series runtime systems are supported.

Platform	Supported CODESYS Runtime System
Raspberry Pi	CODESYS Control for Raspberry Pi MC SL / CODESYS Control for Raspberry Pi SL / CODESYS Control for Raspberry Pi 64 SL
Windows Soft PLC	CODESYS Control Win V3 / CODESYS Control Win V3 x64 / CODESYS Control RTE V3 / CODESYS Control RTE V3 x64
Linux	CODESYS Control for Linux ARM SL / CODESYS Control for Linux ARM64 SL / CODESYS Control for Linux SL
Virtual Controller	CODESYS Virtual Control for Linux ARM SL / CODESYS Virtual Control for Linux ARM64 SL / CODESYS Virtual Control for Linux SL

Minimum supported Runtime System version

Runtime Systems from CODESYS V3.5 SP19 onwards include User Management functions. Older, less secure communication protocols used in earlier versions have not been re-implemented in CODESYS 4.

Connecting to PLCs is handled via CODESYS Gateway. In other words, CODESYS 4 does not force backward compatibility with legacy runtimes, but instead operates on the premise of:

V3.5 SP19以降
User Management
CODESYS Gateway

switching communication to a security-oriented structure.

CODESYS 4 Version 1.0.0.0 is not a beta version

CODESYS 4 is officially approved for production use for library development and small-scale projects. Quality standards are equivalent to CODESYS 3.

In addition,

Compiler
Runtime System
Gateway

have not been changed from previous versions. What is new is the development interface. However, compared to CODESYS Development System 3, available functions are currently quite limited.

Installation

Download the CODESYS 4 installation file from the link below.

https://store.codesys.com/en/codesys-4.html

Windows

To install on Windows, download the installer file (.msi / .exe).

Launch the downloaded setup executable from the CODESYS Store and click Next.

If prerequisite packages such as Microsoft ASP.NET are missing, click “Click here for download” to install the required packages.

Next, accept the license terms and proceed with Next.

Click Next to proceed.

Start the installation.

Finally, launch CODESYS-4.1.xxxx.

Wait a moment…

Done！

Linux

Next, the installation steps for Linux environment are explained.

Installing CODESYS Control SL

First, install CODESYS Runtime on the R1025.

Verify ARM64 architecture

dpkg –print-architecture

Prepare working directory and tools

Downloaded files will be saved in this folder hereafter.

mkdir –p /home/recomputer/Codesys4 cd /home/recomputer/Codesys4 sudo apt-get update sudo apt-get install –y curl ca-certificates unzip

Download the PLC runtime

What is downloaded here is codesyscontrol for running PLC programs, not the web-based development environment codesys-4.

curl -fL —max-time 180 \ ‘https://store-archive.codesys.com/ftp_download/3S/LinuxARM64/2302000039/4.22.0.0/CODESYS%20Control%20for%20Linux%20ARM64%20SL%204.22.0.0.package’ \ -o /home/recomputer/Codesys4/control-arm64-4.22.package

Extract the ARM64 installer

unzip -n /home/recomputer/Codesys4/control-arm64-4.22.package \ ‘Delivery/linuxarm64/*.deb’ \ -d /home/recomputer/Codesys4/control-4.22

Verify content

dpkg-deb -f \ /home/recomputer/Codesys4/control-4.22/Delivery/linuxarm64/codesyscontrol_linuxarm64_4.22.0.0_arm64.deb \ Package Version Architecture Depends

Upon success, the following contents will be listed:

Package: codesyscontrol Version: 4.22.0.0 Architecture: arm64 Depends: codemeter \| codemeter-lite, …

Install ARM64 CodeMeter and PLC runtime

CodeMeter is the software that manages licenses for CODESYS runtime. Install it along with the main runtime system.

curl -fL —max-time 180 \ ‘https://www.wibu.com/support/user/user-software/file/download/17976.html?tx_wibudownloads_downloadlist%5BdirectDownload%5D=directDownload&tx_wibudownloads_downloadlist%5BuseAwsS3%5D=0&cHash=8dba7ab094dec6267346f04fce2a2bcd’ \ -o /home/recomputer/Codesys4/codemeter-arm64.deb

Install both packages together

sudo apt-get install -y \ /home/recomputer/Codesys4/codemeter-arm64.deb \ /home/recomputer/Codesys4/control-4.22/Delivery/linuxarm64/codesyscontrol_linuxarm64_4.22.0.0_arm64.deb

Verify runtime startup

systemctl is-active codesyscontrol codemeter systemctl is-enabled codesyscontrol

Download and extract Gateway

Gateway connects the CODESYS development environment to the PLC runtime on R1025. Install it on the same R1025 unit.

curl -fL –max-time 180 \ ‘https://store-archive.codesys.com/ftp_download/3S/EdgeGatewayLinux/000120/4.22.0.0/CODESYS%20Edge%20Gateway%20for%20Linux%204.22.0.0.package’ \ -o /home/recomputer/Codesys4/edge-gateway-4.22.0.0.package unzip -n /home/recomputer/Codesys4/edge-gateway-4.22.0.0.package \ ‘Delivery/edgearm64/*.deb’ \ -d /home/recomputer/Codesys4/edge-gateway-4.22

Install Gateway

sudo apt-get install -y \ /home/recomputer/Codesys4/edge-gateway-4.22/Delivery/edgearm64/codesysedge_edgearm64_4.22.0.0_arm64.deb

Verify Gateway startup

systemctl is-active codesysedge systemctl is-enabled codesysedge

Installing CODESYS 4

Install .NET execution environment

Add ASP.NET Core Runtime to run CODESYS 4 browser development environment.

curl -fL https://dot.net/v1/dotnet-install.sh \ -o /tmp/codesys-dotnet-install.sh sudo bash /tmp/codesys-dotnet-install.sh \ –runtime aspnetcore \ –version 8.0.29 \ –architecture arm64 \ –install-dir /usr/share/dotnet \ –no-path /usr/share/dotnet/dotnet –list-runtimes

Install CODESYS 4

sudo dpkg -i /home/recomputer/Codesys4/codesys-4_1.0.0.0_arm64.deb dpkg -s codesys-4 sudo dpkg –audit

Register login user

sudo usermod -aG codesys-4 recomputer id recomputer

Create development server service

nano /etc/systemd/system/codesys-4-web.service

Paste the following contents. In nano, press Ctrl+O → Enter to save, then Ctrl+X to exit.

[Unit]
Description=CODESYS 4 Web Server
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
User=recomputer
Group=recomputer
WorkingDirectory=/opt/codesys-4
Environment=DOTNET_ROOT=/usr/share/dotnet
ExecStart=/opt/codesys-4/c4-server multisession –port 8080 –login-groups codesys-4
Restart=on-failure
RestartSec=5
TimeoutStopSec=30

[Install]
WantedBy=multi-user.target

Start and verify service

Reload systemd configurations, start the service, and enable automatic startup.

sudo systemctl daemon-reload sudo systemctl enable –now codesys-4-web systemctl is-active codesys-4-web systemctl is-enabled codesys-4-web curl -I http://127.0.0.1:8080/

In this environment, the development server listens on localhost port 8080. Next, configure nginx to allow HTTPS access over LAN. LAN publishing via `ASPNETCORE_URLS` will not be used as it was ineffective in testing.

Install nginx

sudo apt-get install -y nginx-light sudo install -d -m 700 /etc/nginx/codesys-tls sudo ss -lntp \| grep ‘:443’

Create SSL certificate

sudo ls -l /etc/nginx/codesys-tls/ sudo openssl req -x509 -newkey rsa:2048 -sha256 -nodes \ -days 365 \ -keyout /etc/nginx/codesys-tls/server.key \ -out /etc/nginx/codesys-tls/server.crt \ -subj ‘/CN=192.168.5.33’ \ -addext ‘subjectAltName=IP:192.168.5.33,DNS:reComputer-R100x’ sudo chmod 600 /etc/nginx/codesys-tls/server.key

Save nginx proxy configuration

sudo nano /etc/nginx/conf.d/codesys-4-https.conf

server {
listen 192.168.5.33:443 ssl;
server_name 192.168.5.33;

ssl_certificate /etc/nginx/codesys-tls/server.crt;
ssl_certificate_key /etc/nginx/codesys-tls/server.key;
ssl_protocols TLSv1.2 TLSv1.3;
client_max_body_size 200m;

location / {
proxy_pass http://127.0.0.1:8080;
proxy_http_version 1.1;
proxy_set_header Host $http_host;
proxy_set_header X-Forwarded-Proto https;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection “upgrade”;
proxy_read_timeout 3600s;
proxy_send_timeout 3600s;
proxy_buffering off;
}
}