CODESYS 4 Version 1.0.0.0 Released:
Web-based development environment for IEC 61131-3
CODESYS 4 will be available in version 1.0.0.0 starting September 24, 2026. It is a second programming system alongside the CODESYS Development System (V3). Programming continues to be done in accordance with IEC 61131-3, using Structured Text and Ladder Diagram. What’s new is the underlying technology: The user interface runs in a browser window; the project is stored on the hard drive as a folder containing text files; and in addition to the graphical user interface, the command-line tool c4-cli is available as an equivalent means of operation. The development environment itself runs on Windows x64, Linux x64, and Linux ARM64.
Nothing changes at the execution level. CODESYS 4 uses the same CODESYS compiler as the CODESYS Development System (V3) and the same libraries; the same runtime system runs on the controller. Code compiled by CODESYS 4 therefore runs on any controller that already executes CODESYS 3 code today. There is no major change to the runtime system, as was the case with the transition from CODESYS V2 to CODESYS V3. A CODESYS-specific runtime system starting with Service Pack 18 and the CODESYS Gateway starting with version 3.5 are required.
Screenshot of the CODESYS 4 interface: on the left is the project tree with the project's files; on the right is the Structured Text editor with color-coded syntax highlighting.
The feature set of version 1.0.0.0 is limited and approved for two use cases: library development in Structured Text with automated compilation via the command line, and small device projects with a few digital and analog inputs and outputs via Modbus TCP. This version is not a beta: It is approved for productive use in these two cases, and the quality standards correspond to those of CODESYS 3. Outside of these two scenarios, CODESYS 3 remains the tool for productive work; even within these scenarios, some features from CODESYS 3 are still missing, particularly the online functions for the running controller, such as Online Change, breakpoints, and writing to and forcing variables.
CODESYS 4 does not replace CODESYS 3. Both tools will continue to be developed and maintained in parallel; there are no plans to discontinue the CODESYS Development System (V3). Combining both environments is also a planned approach; for example, developing in CODESYS 4 and commissioning in the CODESYS Development System (V3). Library projects from CODESYS 3 in file-based storage open in CODESYS 4 and vice versa; device projects require conversion, and file-based storage is expected to provide this functionality in the future.
Release Extension
Availability
CODESYS 4, Version 1.0.0.0, will be available starting September 23, 2026, as an installer (.exe) for Windows x64 and as a Debian package (.deb) for Linux x64 and Linux ARM64. Use is free through the end of 2028; a paid licensing model is planned for 2029 at the earliest. The CODESYS Development System (V3) remains free of charge. Available through the CODESYS Store.
What Version 1.0.0.0 Offers
- A Structured Text editor with syntax highlighting, auto-completion, and tooltips when hovering over text, plus the Contact Plan Editor in version 0.1 with basic offline functionality.
- Projects are stored as directories in JSON, XML, and plain text, without a proprietary binary format. This allows projects to be stored in Git, compared during code reviews, and merged using standard tools.
- Library management using
Libraries.jsonandLibraries.lock.json. The lock file records the resolved dependency tree with exact versions and checksums, ensuring that a machine in the pipeline resolves the same dependencies as the workstation. A pipeline is a process running on a server that automatically starts upon a specified event and compiles and tests your code. - Command-line tool
c4-clifor Windows x64, Linux x64, and Linux ARM64: generate compiled libraries and boot applications, manage dependencies, create workspaces, log in and out of the control system, and reset the control system. - Modbus Configurator as an extension for projects with a small number of inputs and outputs via Modbus TCP.
- Can be operated as a standalone application on Windows, as a standalone application on Linux, as a shared server for a team, or directly on a controller. An internet connection is not required for operation.
- User interface in German and English, each with light and dark color schemes; operated via keyboard through the Command Center.
In version 1.0.0.0, only CODESYS’s own runtime systems are approved for project configuration. The complete list, supported operating modes, and system requirements can be found on the CODESYS 4 product page.
New versions are released on an ongoing basis as full releases (1.0.0.0, 1.1.0.0, etc.); service packs and patches are not planned.
If you’d like to stay informed about new versions, you can sign up for the Early Adopter Program.