Hi,
I've been using python-snap7 for a while to control a Siemens S7-300 PLC (Stop/Hot Start/Cold Start). After the upgrade to 3.0, all three control commands consistently fail with:
S7 protocol error (class=0x81, code=0x04): This service is not implemented on the module or a frame error was reported
The same commands worked perfectly with python-snap7 2.x (C library wrapper) against the same PLC and the same rack/slot configuration. My log clearly shows successful Stop and Hot Start on 2026-05-28 and 2026-05-29 with the old version, and consistent failures from 2026-05-31 onwards after the upgrade to 3.0 (after updating the libary).
Setup:
- PLC: Siemens S7-300
- Rack 0, Slot 2
- python-snap7: 3.0.0
- Python: 3.11, Windows
Workaround for now: pip install "python-snap7<3", which works in the moment
Thanks for the great library!
Hi,
I've been using python-snap7 for a while to control a Siemens S7-300 PLC (Stop/Hot Start/Cold Start). After the upgrade to 3.0, all three control commands consistently fail with:
S7 protocol error (class=0x81, code=0x04): This service is not implemented on the module or a frame error was reported
The same commands worked perfectly with python-snap7 2.x (C library wrapper) against the same PLC and the same rack/slot configuration. My log clearly shows successful Stop and Hot Start on 2026-05-28 and 2026-05-29 with the old version, and consistent failures from 2026-05-31 onwards after the upgrade to 3.0 (after updating the libary).
Setup:
Workaround for now: pip install "python-snap7<3", which works in the moment
Thanks for the great library!