python-snap7

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python-snap7

python-snap7 is a pure-Python library for communicating with Siemens S7 PLCs using the classic S7 protocol. It supports S7-300 and S7-400 controllers, as well as S7-1200 and S7-1500 controllers with PUT/GET access enabled. It supports Python 3.10+ on Windows, Linux, and macOS without native dependencies.

S7-1200 and S7-1500

On S7-1200 and S7-1500 controllers, python-snap7 only works when PUT/GET access is enabled in TIA Portal, and it cannot access optimized data blocks. PUT/GET is unauthenticated and disabled by default, so leaving it disabled is the more secure configuration.

If PUT/GET is disabled, or you need optimized data blocks or symbolic access, use s7commplus <https://github.com/gijzelaerr/s7commplus>_ instead::

pip install s7commplus

s7commplus is a separate, younger project that implements S7CommPlus, the protocol these controllers speak natively. Check the firmware versions validated so far <https://s7commplus.readthedocs.io/en/latest/connections.html>_ before relying on it, and see the PLC support matrix <https://python-snap7.readthedocs.io/en/latest/plc-support.html>_ for what python-snap7 supports on each controller family.

Installation

Install from PyPI::

pip install python-snap7

Quick start

::

from s7 import Client

client = Client() client.connect(“192.168.1.10”, 0, 1) data = client.db_read(1, 0, 4) client.disconnect()

The s7 package is the recommended import. The snap7 package name is also available for backwards compatibility.

Documentation

Read the full documentation at python-snap7.readthedocs.io <https://python-snap7.readthedocs.io/en/latest/>_.

The safe volunteer hardware-test procedure is in Real-PLC acceptance testing <doc/real-plc-testing.rst>. The CPUs and firmware versions it has passed on are listed under Tested and Verified Hardware <doc/plc-support.rst>.