gx3-cli-mcp

Work out why a coil never turns on, without opening GX Works3.

gx3-cli-mcp reads a GX Works3 (.gx3) project on your own machine and answers questions about it: where a device is written, what has to be true for a coil to turn on, which conditions come from outside the PLC, and which branches can never be true at all. It is read-only and never writes back to the project.

It is a CLI, and it is also a stdio MCP server, so an AI agent can answer from the same indexed facts instead of guessing at a binary file.

That matters for three reasons:

• A GX Works3 licence is not on everyone's desk. Maintenance, production engineering, quality and upstream software all end up asking whoever has one.
• Following a coil upstream is where people lose the thread, usually about three cross-reference hops in. A machine does not lose the thread.
• You should not need to know the device number. Search the comment you actually remember, and every answer comes back with its comment attached.

日本語: 三菱電機の MELSEC シーケンサ（PLC）のプロジェクトファイル .gx3 を、 GX Works3 を開かずに解析する CLI / MCP サーバーです。「このコイルがなぜ ON に ならないか」をラダーから追い、クロスリファレンスを何度も開く代わりに一度で 答えます。読み取り専用で、元のプロジェクトファイルは書き換えません。 ライセンスが手元に無い人でも調べられること、デバイス番号を知らなくても デバイスコメントから引けることを狙っています。

紹介記事: GX Works3 を開かずにラダーを追えるようにした — 何ができるかは、実際の出力つきでこちらにまとめています。

Try It Without a Real Project

You do not need a .gx3 you are allowed to share. Generate a synthetic one:

python -m pip install gx3-cli-mcp
gx3-cli synthetic-project line.gx3 --profile demo-line --overwrite
gx3-cli index-lite build --root line.gx3
gx3-cli xref build --root line.gx3
gx3-cli trace-device M2313 --root line.gx3 --strict-logic --compact

That builds a fictional 14-station transfer line — about 500 rungs across 10 programs — and traces one step back through every station upstream of it.

This is an unofficial, independent tool. It is not endorsed by Mitsubishi Electric.

Questions This Answers

日本語の質問例も併記しています。CLI でも、MCP 経由で AI エージェントに聞く場合でも同じです。

Where is this device written, and where is it read? このデバイスはどこで書かれて、どこで読まれているのか

gx3-cli xref where-used M2313 --root project.gx3

Why does this coil never turn on? なぜこのコイルが ON にならないのか / 起動条件は何か

gx3-cli trace-device M2313 --root project.gx3 --strict-logic --compact

Which conditions come from outside the PLC? どの条件が外部入力・HMI・通信から来ているのか（＝ラダーではなく盤を見るべきか）

trace-device の出力に External/HMI/communication boundaries として出ます。

I only remember what the device is called, not its number. デバイス番号は覚えていないが、コメントの文言なら分かる

gx3-cli query-comment "クランプ確認" --root project.gx3

Is anything in this project dead or contradictory? 二重コイル、リセットの無いラッチ、成立しない条件、矛盾したコメントはないか

gx3-cli lint project.gx3
gx3-cli dead-logic --root project.gx3

Can an AI agent answer these instead of me typing commands? コマンドを覚えずに、Claude や Cursor から日本語で聞けるか

Yes — that is what the MCP server is for. See Use With MCP. gx3-mcp-server を Claude Desktop / Claude Code / Cursor などの MCP クライアント に登録すると、エージェントが上記の解析を呼び出して、根拠つきで答えます。

Scope

• Supported: MELSEC iQ-R / iQ-F series projects saved as .gx3 by GX Works3. 三菱電機の MELSEC シーケンサ、GX Works3 の .gx3 形式。
• Not supported: GX Works2 (.gxw), GX Developer (.gpj), and .gx3 files saved with the compressed/lightweight option, which are password protected and cannot be extracted. 軽量保存された .gx3 は展開できません。
• Not a substitute for GX Works3, for PLC validation, or for your own safety and quality review. Output is advisory.

Verified coverage is listed in docs/VALIDATION_MATRIX.md.

How This Reads .gx3, And What It Does Not Do

This project is unofficial and independent. It is not affiliated with, endorsed by, or supported by Mitsubishi Electric. GX Works3 and MELSEC are their trademarks, used here only to say what this tool reads.

What it does:

• It opens a .gx3 data file that the user already has on their own machine and reads the SQLite databases and text inside it. The format was worked out by looking at project files the author is authorised to work with.
• It uses only the Python standard library — zipfile and sqlite3. The project has no third-party dependencies and bundles, links against, or redistributes no Mitsubishi Electric code, libraries, or assets of any kind.

What it does not do:

• It does not decompile, disassemble, patch, instrument, or otherwise analyse GX Works3 or any other Mitsubishi Electric software. It never runs their software and never touches its binaries.
• It does not remove, defeat, or work around any access control. A .gx3 saved with the compressed/lightweight option is password protected, and this project contains no code to decrypt one and will not gain any — that format is listed as unsupported in Scope and stays that way by choice, not by oversight.
• It does not modify the project. The archive is extracted to a local cache and only that copy is read; the original file is never written back to.
• It does not communicate with a PLC, a network, or any remote service.
• It does not reproduce Mitsubishi Electric's software, documentation, or file format specification. It reads a customer's own data.

Using this tool does not change the agreements you have with Mitsubishi Electric. Complying with the terms of your GX Works3 licence, and with your employer's and customers' rules about project data, remains yours.

If Mitsubishi Electric has a concern about this project, please open an issue or contact the author through GitHub; it will be addressed.

日本語: 本プロジェクトは非公式・独立のもので、三菱電機とは無関係です。読むのは 利用者が自分の手元に持っているデータファイル（.gx3）だけで、形式は作者が 業務上アクセスできるプロジェクトファイルを観察して把握しました。GX Works3 を はじめとする三菱電機のソフトウェアを逆アセンブル・デコンパイル・改変することは 一切していません。三菱電機のコードやライブラリを同梱・参照・再配布もしていません （依存パッケージはゼロで、Python 標準ライブラリのみを使います）。

保護の解除も行いません。 軽量保存された .gx3 はパスワード保護されており、 本プロジェクトには復号のためのコードが存在しません。今後も実装しません。これは 実装漏れではなく方針です。

GX Works3 のライセンス条項や、勤務先・顧客のプロジェクトデータの取り扱い規則を 守る責任は利用者にあります。三菱電機の方でご懸念があれば、Issue または GitHub 経由でご連絡ください。対応します。

What You Can Do

• Find where a device is used and whether it is read, written, or referenced.
• Search device comments such as start, stop, alarm, cycle, step, or manual operation keywords.
• Trace upstream conditions for a coil and print nearby ladder evidence.
• Build xref and SQLite indexes so AI agents can answer from structured facts.
• Review static risks such as duplicate coils, multi-writers, dead logic, and interlock possibilities.
• Inspect external inputs, HMI/communication boundaries, IP maps, link maps, timing candidates, and project-wide summaries.

What It Does Not Do

• It does not include real customer or production PLC projects.
• It does not send project data to an online service by itself.
• It does not provide a GUI in this release.
• It does not require a license token or paid-plan token.
• The MCP server does not expose project-mutating commands.

Install

python -m pip install gx3-cli-mcp
gx3-cli --version
gx3-mcp-server --version

Requires Python 3.10 or later. Installing into a virtual environment is recommended so the two console scripts stay off the system PATH.

If your site blocks PyPI, install the latest source directly:

python -m pip install git+https://github.com/purinzan/gx3-cli-mcp.git

For a local source checkout:

python -m pip install -e .

日本語: 通常は pip install gx3-cli-mcp だけで CLI と MCP サーバーの両方が 入ります。社内プロキシで PyPI に到達できない場合のみ、上の git 直接指定を 使ってください。

First Analysis

Run these three commands first for a real project:

gx3-cli doctor --root C:\path\to\project.gx3
gx3-cli index-lite build --root C:\path\to\project.gx3
gx3-cli xref build --root C:\path\to\project.gx3

Then inspect a device:

gx3-cli query-device M100 --root C:\path\to\project.gx3
gx3-cli xref where-used M100 --root C:\path\to\project.gx3
gx3-cli trace-device M100 --root C:\path\to\project.gx3 --strict-logic --compact

When you pass a .gx3 file, the tool extracts it into .gx3_cache\<sha256>\ and analyzes that local cache.

Common Tasks

Use the indexed commands above for normal lookup and discovery. Avoid starting AI workflows with raw text search over extracted GX3 files; GX Works3 projects contain binary/database files, and the CLI preserves device, comment, POU, role, and step context.

Use With MCP

The MCP server is intended for AI clients that support stdio MCP servers.

{
  "mcpServers": {
    "gx3": {
      "command": "python",
      "args": ["-m", "gx3cli.gx3_mcp_server"]
    }
  }
}

If your client can resolve console scripts from PATH:

{
  "mcpServers": {
    "gx3": {
      "command": "gx3-mcp-server"
    }
  }
}

The MCP server exposes read-only analysis tools and a restricted command runner. Synthetic demo generation is local CLI-only.

Demo Project

Two synthetic profiles, neither of which contains anything real. See Try It Without a Real Project for the quick start.

basic (the default) is three rungs — enough to check that a command runs:

gx3-cli synthetic-project demo.gx3 --overwrite
gx3-cli doctor --root demo.gx3
gx3-cli trace-device M100 --root demo.gx3 --strict-logic --compact

demo-line is a 14-station pick-and-place line: about 500 rungs across 10 programs with roughly 500 commented devices, chained so that tracing an output on the last station walks back through every station upstream. Use this one for demos, for screenshots, and for reproducing a bug without sending anyone a real project.

gx3-cli synthetic-project line.gx3 --profile demo-line --overwrite
gx3-cli lint line.gx3
gx3-cli dead-logic --root line.gx3

It also contains a small number of deliberate faults - a duplicate coil, a latch with no reset, a coil nobody reads, a contact that can never close, and two devices whose comments contradict each other - so the review commands report findings instead of an empty table. This is also the fastest way to reproduce a bug for an issue without sending anyone a real project.

Data And Safety

• Project files stay on your machine unless you pass outputs to another tool.
• Some commands create local files such as SQLite indexes, CSV reports, ZIP support bundles, or Markdown summaries.
• Analysis output is advisory. Verify findings in GX Works3 and through your own safety/quality process before changing real equipment.
• The tool is not a substitute for PLC validation, machine safety review, or official engineering software.

Documentation

Recommended reading:

1. User manual (JA): Japanese install and usage guide.
2. Agent usage guide (JA): how AI agents should use the indexed tools.
3. Security note (JA): local data handling and read-only MCP policy.
4. Validation matrix (JA): verified scope and limitations.
5. File usage guide (JA): repository file map for agents and contributors.

llms.txt is a short machine-readable summary of what this project is and is not, for tools that index repositories for AI assistants.

MCP configuration examples:

• MCP client config: robust python -m gx3cli.gx3_mcp_server launch.
• MCP client config, console script: direct gx3-mcp-server launch when PATH is reliable.

License In Plain Words

Full terms are in LICENSE.txt; this section is only a summary and the license text governs.

This is source-available proprietary software, not open source. In practice:

• You may clone it, read the source, and run it for evaluation and for internal analysis work, including inside a company.
• You may not redistribute it, host it as a service, resell it, or ship it as part of a paid product or commercial service without written permission.
• There is no license token, activation, or paid plan to run it.
• It is provided as is, with no warranty, and its output is advisory only.

日本語: 社内での評価・業務利用は許諾されています。禁止しているのは再配布、 SaaS としての提供、有償製品やサービスへの組み込みです。実行にライセンス キーや課金は不要です。商用利用の相談は Issue からご連絡ください。

For Contributors

Bug reports, questions, and small pull requests are welcome, in Japanese or English. Start with CONTRIBUTING.md, which covers the no-project-data rule, the development setup, and what a useful bug report contains. Issues labeled good first issue are scoped to be approachable without deep knowledge of the GX Works3 file format.

Before changing or publishing this project, run the same checks used by CI:

python run_tests.py
python scripts\release_gate.py .
python -m build --wheel
python scripts\release_gate.py dist\gx3_cli_mcp-*.whl