s7commplus

Pure-Python S7CommPlus communication for Siemens S7-1200 and S7-1500 PLCs. It supports S7CommPlus V1, V2 (TLS), and V3; synchronous and asyncio clients; and a server emulator for testing. The synchronous client additionally supports legacy V1 SessionKey authentication; the asyncio client rejects that path during connection with an actionable error.

pip install s7commplus

from s7commplus import Client

with Client() as client:
    client.connect("192.168.1.10", 0, 1)
    data = client.db_read(1, 0, 4)

S7CommPlus is used by newer S7-1200/1500 PLCs when classic PUT/GET access is disabled. This is an unofficial implementation and is not affiliated with, endorsed by, or supported by Siemens AG. Test against an isolated controller before using it in production or safety-relevant environments.

Some older PLCs advertise only their SessionKey family instead of a complete public-key fingerprint. The synchronous Client tries the bounded set of bundled keys from that family on fresh sessions and caches the confirmed key for the PLC. Set allow_legacy_key_fallback=False on connect() when key probing must be disabled.

Development

python -m pip install -e '.[test]'
pytest
mypy s7commplus
ruff check s7commplus tests
ruff format --check s7commplus tests

Documentation is built by Read the Docs and validated in CI:

python -m pip install -e '.[docs]'
sphinx-build -W --keep-going -b html docs docs/_build/html

The session-authentication implementation derives from HarpoS7; its MIT license is included at s7commplus/session_auth/LICENSE-HarpoS7.