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. Both clients support legacy V1 SessionKey authentication, validated on a real S7-1200 (sync and async clients), an S7-1500 (sync client), and S7-PLCSIM Advanced (sync and async clients).

Install the latest stable release from PyPI:

python -m pip install --upgrade s7commplus

See the s7commplus documentation for the complete user guide and API reference.

from s7commplus import Client

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

Optimized blocks are read and written by tag name, as Python values; a struct, UDT or array name gives a dict or list:

with Client() as client:
    client.connect("192.168.1.10", use_tls=True, tls_ca="plc-ca.pem")  # verify the PLC certificate
    temperature = client.read_value("Data_block_1.temperature")
    client.write_value("Data_block_1.recipe", {"speed": 120, "name": "batch 7"})

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. Client and AsyncClient try the bounded set of bundled keys from that family on fresh sessions and cache the confirmed key for the PLC. Set allow_legacy_key_fallback=False on connect() when key probing must be disabled.

The order number a PLC reports during connect can be turned into a readable module name and family:

from s7commplus import device_family, device_name

device_name("6ES7 512-1DK01-0AB0")   # 'CPU 1512SP-1 PN'
device_family("6ES7 512-1DK01-0AB0")  # 's7-1500-sp'

DEVICE_NAMES holds the full table (S7-1200/1500 controllers, SIPLUS variants, software controllers and PLCSIM; classic S7-300/400 is out of scope). python tools/check_devices_table.py validates its shape.

Installing the package also installs a s7commplus command-line tool:

s7commplus browse --host 192.168.1.10
s7commplus read --host 192.168.1.10 DB1.Motor.Speed

See the command-line interface guide in the documentation.

Cloning the repository is only necessary for developing or testing s7commplus. To use the stable library in an application, install it from PyPI as shown above.

git clone https://github.com/gijzelaerr/s7commplus.git
cd s7commplus
python -m pip install -e '.[test,docs]'
pytest
mypy s7commplus
ruff check s7commplus tests
ruff format --check s7commplus tests

The published documentation is hosted on Read the Docs and validated in CI. To build it locally from a development checkout:

sphinx-build -W --keep-going -b html docs docs/_build/html

The V1 SessionKey implementation derives from HarpoS7; its MIT license is included at s7commplus/v1_session_key/LICENSE-HarpoS7.