Siemens SIMATIC AX Brings Git and DevOps to PLC Programming

Siemens is introducing software-engineering practices to industrial automation with SIMATIC AX, a Visual Studio Code-based toolset designed to bring version control, automated testing, and continuous integration workflows to programmable logic controller (PLC) development.

Built around IEC 61131-3 Structured Text, SIMATIC AX treats control logic as source code rather than proprietary project files. Engineers can store programs in Git repositories, manage dependencies as versioned packages, write unit tests, and automate build and deployment steps from the command line. The approach mirrors enterprise software development, where distributed teams collaborate through pull requests and code reviews rather than passing project files.

Why it matters

As machine portfolios grow more complex and engineering teams become geographically distributed, traditional PLC workflows—optimized for single-site commissioning—struggle to scale. Late-cycle validation, limited traceability, and copy-paste reuse create hidden lifecycle costs that compound across machine variants and long-term maintenance. SIMATIC AX addresses these friction points by enabling practices that enterprise software teams have relied on for years: systematic code review, regression testing, and safe parallel development. For manufacturers managing fleets of similar machines or standardizing libraries across plants, the shift from project-centric to source-centric engineering can reduce rework and improve update discipline without sacrificing control-system reliability.

Target audience and use cases

Siemens positions SIMATIC AX primarily for machine builders and system integrators managing software complexity across multiple similar machines. The toolset is particularly relevant for organizations that already use Git for version control, want to build and maintain reusable component libraries, or need multiple engineers to work on the same codebase simultaneously.

Siemens has also extended the AX concept to human-machine interfaces with SIMATIC AX WinCC Unified Elements, which applies the same source-centric, Git-friendly approach to HMI and SCADA development. Both tools support command-line automation and CI/CD pipelines, enabling teams to integrate quality checks into their release processes.

Relationship to TIA Portal

SIMATIC AX is not a replacement for TIA Portal, Siemens' established engineering environment. TIA Portal remains the central tool for hardware configuration, network setup, safety logic, technology objects, drives, and commissioning workflows. SIMATIC AX focuses specifically on the PLC software lifecycle—developing, versioning, and testing control logic and libraries.

In practice, many users are expected to develop and version software components in AX, then import those assets into TIA Portal projects to complete full machine engineering. SIMATIC AX Logic Control Engineering can handle the complete PLC workflow independently, including loading programs to controllers, but the broader ecosystem still relies on TIA Portal for end-to-end project integration.

Industry context

The move reflects a broader shift in industrial automation. Control applications are growing larger and more connected, machine variants are proliferating, and engineering teams are increasingly distributed across sites. Traditional workflows—where engineers build logic inside proprietary containers and validate primarily during commissioning—can limit traceability, reuse, and safe parallel development as software complexity increases.

By introducing Git-based collaboration, package management, and automated testing, Siemens is positioning SIMATIC AX to help automation engineering adopt the repeatable, scalable practices that have become standard in enterprise software development. The challenge will be execution: successful adoption depends on smooth interoperability with TIA Portal and acceptance among teams accustomed to graphical programming languages and commissioning-driven validation.

These details were first reported by ARC Advisory Group in an industry analysis examining Siemens' software-centric automation strategy.