aslmp
An async Python client for the SLMP protocol that Mitsubishi MELSEC PLCs speak over Ethernet, built from the observed behavior of a real CPU rather than its manual.
aslmp is an async Python client for SLMP, the successor to MC protocol that Mitsubishi MELSEC CPUs speak over Ethernet. It offers both an async interface and a synchronous facade with the same method names running on one background event loop, plus a command-line tool with twelve subcommands. It has zero runtime dependencies and is mypy --strict clean.
The README documents several failure modes the author measured directly against real hardware rather than trusting the manual: two TCP requests in flight can return one response for the wrong request, a UDP burst deeper than 32 silently loses the excess, and X/Y device numbers are octal on iQ-F CPUs, so a value typed as decimal lands on the wrong output. It states plainly that it is not a certified safety system, that SLMP has no authentication or encryption, and that it can halt a running CPU when remote control is allowed.
It is released under the Apache-2.0 license.