plc-programming: a Claude Code & Antigravity plugin

This plugin lets AI coding assistants (Claude Code, Antigravity / Gemini) design, write, extend, convert, review and debug PLC programs through conversation, backed by standards knowledge that was checked against sources (September 2026) and by a validator that uses only the Python standard library.

The focus is Siemens (TIA Portal / S7) and Schneider Electric (Machine Expert / M2xx, Control Expert / M340–M580). It also covers the vendor-neutral standards and the other major platforms.

Install

Claude Code

claude plugin marketplace add SmailG/plc-programming
claude plugin install plc-programming@plc-programming

For development without installing, run claude --plugin-dir . from a checkout of this repository.

Antigravity / Gemini

Install globally across all workspaces:

git clone https://github.com/SmailG/plc-programming.git ~/.gemini/config/plugins/plc-programming

Or for a single workspace:

git clone https://github.com/SmailG/plc-programming.git .agents/plugins/plc-programming

What is inside

Component	Invocation	Purpose
develop skill	automatic, or /plc-programming:develop	frame → requirements → design → code → validate → test plan; changing existing code safely
debug skill	automatic, or /plc-programming:debug	evidence-first diagnosis, with a catalogue of PLC failure patterns
convert skill	automatic, or /plc-programming:convert	port between languages, dialects and exchange formats without changing behaviour per scan
siemens skill	automatic	TIA Portal, S7-1200/1500, SCL/LAD/FBD/STL/GRAPH, SimaticML, SIMATIC SD, AX, PROFINET/S7/OPC UA, Safety Integrated
schneider skill	automatic	Machine Expert (M241/M251/M262), Control Expert (M340/M580), Automation Expert, Modbus, EtherNet/IP, OPC UA
iec-61131-3 skill	automatic	Ed.2–Ed.4, the five languages, POUs, OOP, data types, the standard library, PLCopen guidelines, Motion and Safety
exchange-formats skill	automatic	PLCopen XML (TC6 v2.0/v2.01), IEC 61131-10, AutomationML (IEC 62714), DEXPI / ISO 15926
other-platforms skill	automatic	Beckhoff TwinCAT, CODESYS, ABB Freelance (PRT/CSV) / AC500 / 800xA, Rockwell L5X/L5K
iec-61499 skill	automatic	event-driven FBs, ECC, 4diac file formats
packml-isa88-opcua skill	automatic	PackML states and PackTags, ISA-88 / IEC 61512, OPC UA (OPC 30000/30001/30050)
/plc-programming:new-pou	user only	scaffold a POU for a chosen platform and format
/plc-programming:review	user only	ranked review by the plc-reviewer agent
/plc-programming:validate	user only	run the validator and explain the findings
plc-reviewer agent	delegated	read-only review against the checklist in skills/develop/references/review-checklist.md
PostToolUse hook	automatic	validates every PLC file written or edited (Claude Code and Antigravity); errors are fed back. Set PLC_VALIDATE_HOOK=0 to disable it

The validator

python3 scripts/plc_validate.py <files-or-dirs> [--format FMT] [--xsd schema.xsd] [--json] [--strict]

It needs Python 3.9 or later and nothing else. It is a structural check, not a compiler: it resolves no types and no symbols across files.

Prefix	Format	Examples of what it catches
ST	IEC ST, Siemens SCL sources, TwinCAT/CODESYS ST, Logix ST	unbalanced blocks (ST002), IF without THEN (ST003), EXIT outside a loop (ST005), = used as assignment (ST010), REAL equality (ST020), timer/edge/counter instances not called exactly once per scan (ST030–ST033), duplicate declarations (ST040)
PX	PLCopen XML v2.0/v2.01, IEC 61131-10	required headers, duplicate localId, dangling refLocalId, SFC initial step, qualifier and duration rules, POUs hidden in vendor addData
SM / SD	SimaticML / SIMATIC SD	namespace version against the TIA version, duplicate ID/UId, dangling wires, invalid interface sections
TC	TwinCAT .TcPOU/.TcDUT/.TcGVL/.TcIO	declaration name against object name and file name, duplicate GUIDs, embedded ST
LX	Rockwell L5X / L5K	rung syntax, operand counts (old and v36 IEC mnemonics), duplicate tags, OTE on the same bit in several rungs
CX	Control Expert XEF/XSY	duplicate variables, shared addresses, embedded ST
FB	IEC 61499 .fbt/.adp	WITH targets, ECC states, algorithms, events, network connections
AM / DX / CS	AutomationML, DEXPI, CSV tag lists	IDs, links, refURI targets, duplicate names

The official XSDs (PLCopen TC6, IEC 61131-10) are not bundled because their licences do not clearly permit redistribution. Download them from https://www.plcopen.org/downloads/ and pass --xsd.

Tests and evals

python3 -m unittest discover -s tests                   # validator, templates, skill integrity
claude plugin eval . --trust-plugin --allow-tools Write Edit "Bash(python3 *)" --no-publish

• Unit tests: every validator rule is exercised by an input it must catch and by a valid control it must pass. Every shipped template and every iecst code block in the skills must lint clean.
• Evals: they compare the plugin against a no-plugin baseline on edition facts, SFC semantics, a classic scan-cycle bug, PLCopen XML generation, SimaticML namespaces, ABB Freelance PRT, and the Logix v36 mnemonics.
• plcopen-generate does not separate plugin from baseline. Both arms score 1.00: the baseline already writes the namespace and headers its regex graders check, and no grader type can run plc_validate.py on the output. Its with-only validated grader shows the plugin makes Claude run the validator; the score shows nothing more.
• On macOS, Bash-granting cases refuse to start while ~/.docker holds symlinks, which Docker Desktop creates. DOCKER_CONFIG does not help. Quit Docker Desktop, then mv ~/.docker ~/.docker.eval-bak, run the eval, and move it back. On Linux, install bubblewrap and socat instead.

Accuracy policy

The reference files state what was verified and cite sources. Anything that could not be verified is marked as such, not stated as fact. Examples:

• the internal layout of an ABB Freelance .prt;
• the SimaticML namespaces for TIA V21;
• the current version of EcoStruxure Automation Expert.

When a user's version is newer than the one documented here, the skills tell Claude to ask, not to assume.

Contributing and licence

See CONTRIBUTING.md and the Code of Conduct. Report security issues privately, as described in SECURITY.md.

MIT. Siemens, Schneider Electric, Rockwell, Beckhoff, CODESYS, ABB and the other product names are trademarks of their owners; this plugin is not affiliated with or endorsed by any of them.