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3.0.0 — Pure Python Rewrite

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@gijzelaerr gijzelaerr released this 18 Mar 08:54
· 78 commits to master since this release
3.0.0
f880d8c

python-snap7 3.0.0 — Pure Python Rewrite

This is a major release that completely rewrites python-snap7 as a pure Python S7 communication library. The C snap7 shared library is no longer used — the entire protocol stack (TPKT, COTP, and S7) is now implemented in pure Python.

The name "python-snap7" is historical — the library originally started as a Python wrapper around the Snap7 C library. As of this release, the C library is no longer needed, but the name is kept for backwards compatibility.

What's new

  • Pure Python implementation — no native dependencies, no shared libraries
  • Works everywhere — any platform that runs Python 3.10+, including ARM, Alpine Linux, and other environments where the C library was difficult or impossible to install
  • Easier to extend — new features and protocol support can be added directly in Python
  • Complete TPKT (RFC 1006) and COTP (ISO 8073) transport layer implementation
  • Native S7 protocol PDU encoding/decoding
  • Pure Python server implementation for testing and simulation
  • Full type annotations with mypy strict mode
  • CLI interface for running an S7 server emulator (pip install "python-snap7[cli]")

Breaking changes

This release completely breaks with the previous approach of wrapping the C snap7 shared library. While the public API is largely the same, this is a fundamental change under the hood. If you experience issues:

  1. Please report them on the issue tracker with a clear description and the version you are using (python -c "import snap7; print(snap7.__version__)")
  2. As a workaround, pin to the last pre-3.0 release: pip install "python-snap7<3"

Thanks

Special thanks to the following people for testing, reporting issues, and providing feedback during the 3.0 development:

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