📢 Upcoming Breaking Changes 🛠️ in SIMATIC AX: What to Expect

Dear SIMATIC AX - Community around the world 🌍

I'm writing this early to give you a heads-up: the upcoming SIMATIC AX 2610 major release will introduce a number of breaking changes that affect existing projects planning to update to the newest set of dependencies. While many of these will be straightforward to handle, they clear the path for significantly improved workflows and unlock new capabilities across the entire SIMATIC AX landscape. We believe that early communication and an open exchange will save a lot of friction once the new release goes live.

The changes range from renamed components and updated namespaces to removed deprecated CLI arguments, build workflow updates, and a few technical changes that will require a closer look at existing projects.

To provide you with a high-level overview without delving into every specific detail, please refer to the chapters below. No worries ... comprehensive details will be shared soon.

_{> Note: The 2610 release is not yet live and is currently planned for the end of october 2026. Everything described here reflects the current plan and may be subject to change before the final release.}

Too long; didn't read

Expect:

- Dependency adjustments in `apax.yml` caused by component renamings across the board

- Introduction of a `make.yml` file to your repository which changes the entire build process

- Apax scripts and CI/CD pipelines need a review due to CLI parameter changes

- Breaking changes in the ST compiler force a rebuild

- OPC UA export and client-side integration changes

A new naming convention across components

One of the biggest visible changes is the renaming of SIMATIC AX Logic Control Engineering components to align better with the broader Siemens ecosystem.

This affects a wide range of components, including cli-tools, extensions, libraries, the SDK (Software Development Kit) and the catalog.

For example:

- `@ax/hwc` becomes `@ax-as/hwc`

- `@ax/sdb` becomes `@ax-as/s7-sdb`

Some components only receive a new namespace (`@ax-as`), while others also get a more descriptive name to reflect their target more clearly. In a few cases, components are renamed entirely.

A full list will be included in the migration guide, which will be published later.

Build and dependency updates to plan for

This release will require a review of your `apax.yml` configuration file and the apax workflows you have set up.

In particular:

- SIMATIC AX component names listed in `dependencies`, `devDependencies`, and `catalog` will need to be updated according to the name changes

- Scripts calling these renamed tools will need to be adjusted

- The CLI command `apax build` will be removed and replaced by `apax make`

- Build arguments and build targets (such as S7 or LLVM) will have to be moved from the `apax.yml` into a newly introduced `make.yml` file

That being said, CI pipelines and every project's apax manifestation and build setup will need adjustments to avoid surprises after the upgrade.

Minor tool behaviour changes and CLI argument deprecations

A broad set of previously warned deprecated CLI options will be removed across several tools, including `stc`, `dcp-utility`, `sld`, `hwld`, `test`, `mod`, `mon`, and `sdb`.

Most of these changes require simple script argument updates, for example:

- Replacing older CLI argument names with the newer equivalents, e.g. `--targetIP` becomes `--target`

- Removing no-longer-supported arguments entirely from your custom scripts

Other updates change how the tools actually behave, for example:

- `sld` will require `--input` (changed from optional to mandatory) due to the upcoming `apax make` changes

- The `plc-control` tool will become the central connection manager for shared connections/ online tools like `sld`, for example, will no longer share PLC connections by default

- For `hwc`, the submodule configuration will be stricter and may require explicit `slot` definitions

- The `--reset-plc` argument of the `hwc load` command will change to a separate subcommand `hwc reset-plc`

- and more ...

Overall, small changes on paper, but exactly the kind that tend to break scripts at the least convenient moment. Definitely worth reviewing carefully, especially in already established application environments with custom workflows.

A full list will be available to sort through once the final release notes are out.

Structured Text technical changes that may need deeper review

Some of the more impactful changes are technical and may require updates beyond configuration files and scripts. I'm talking about the ones affecting your actual automation source code logic.

Notably:

- The `TIME` and `TIME_OF_DAY` will change from 64-bit to 32-bit resolution.

ST code that depends on serialization, precision assumptions, or fixed-width behavior may need to be adapted.

- Several very niche system library functions will become internal and can no longer be used directly.

Projects that rely on those functions will need to move to supported alternatives.

- The internally made breaking changes of the ST compiler force libraries and applications to be recompiled as a result this time around.

All you SIMATIC AX library developers out there, prepare to re-release your (public) contributions.

OPC UA users should take note

For OPC UA-related workflows, there will also be two relevant changes:

- Generated NodeSets will use standard type aliases

- NodeSet XML will no longer be automatically written to the previous object directory during compilation

This means both build configuration and client-side integration may need to be updated.

Final thoughts

Most changes are clear and manageable once identified, and the upcoming migration guide is designed to minimize effort. Still, your existing projects will need adaptation, so an early review of the changes in detail will pay off.

Read an early draft of the list of upcoming breaking changes [here].

We'll update our posts with more details as we get closer to the actual 2610 release and since the release is not yet live, some details may still change.

On the other hand there is a lot of awesome news coming your way as we approach the broad release of SIMATIC AX - LCE and beyond 🚀.

As always, stay AXcited.

Your friendly SIMATIC AX neighborhood