GX Works3 PLC analysis MCP server

This is a small helper that reads a Mitsubishi MELSEC GX Works3 project file on your own computer and answers questions about it. It is made for people who work with PLC ladder programs and want a second pair of eyes on a project. It is unofficial and read-only, so it never changes your project.

What this MCP server does

You point the helper at a .gx3 project file on your computer. When you ask your AI something like why a coil stays off, the AI sends that question to this helper. The helper reads the ladder logic in the project, follows the devices and conditions, and sends back what it found. Your AI then explains it to you in the chat, in normal words.

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What you can do with it

• Trace why a specific coil is not turning on
• Find where a device like M100 is written and what reads it
• Search device comments when you remember the name but not the number
• List the whole program as one line per rung
• Spot conditions that come from outside the PLC
• Flag dead logic that can never be true
• Compare two versions of a project to see what changed

Try asking your AI

• “Why is coil M100 not turning on in project.gx3?”
• “Where is device M100 written and what reads it?”
• “Search the comments for clamp pressure and show me the rungs”
• “Show me the whole program as one line per rung”

What it gives back to you

You get answers in the chat: short explanations, lists of devices and rungs, and plain summaries of what the logic does. Some commands can also give you a picture of a rung or a file you can save. Everything comes back as text or a file you can look at, and nothing is written back into your project.

Before you start

Who it's for

PLC programmers, maintenance engineers and automation people who work with Mitsubishi MELSEC GX Works3 projects and want quick answers about ladder logic.