openplc-engineering-mcp

A small Python MCP server that exposes domain-oriented, read-only engineering operations for OpenPLC.

The project is an early experimental implementation. Its current purpose is to establish a minimal, testable integration boundary between MCP-compatible agents and OpenPLC Editor projects.

Architecture

MCP Host / LLM Agent
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        | MCP
        v
OpenPLC Engineering MCP
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        v
OpenPLC

The server uses the official Model Context Protocol Python SDK and stdio transport. It does not modify OpenPLC or expose generic filesystem or shell tools.

Related MCP server: gx3-mcp-server

Requirements

• Python 3.12+

• uv

• Node.js/npm only when using MCP Inspector (mcp dev uses npx)

Installation

git clone https://github.com/industrix-com-br/openplc-engineering-mcp.git
cd openplc-engineering-mcp
uv sync

Running

Start the stdio MCP server:

uv run openplc-engineering-mcp

Open it with MCP Inspector:

uv run mcp dev src/openplc_engineering_mcp/server.py --with-editable .

Testing

uv run pytest

The tests use the official SDK's in-memory Client(mcp) interface rather than calling tool functions directly.

Current tools

• get_server_info — reports the server's current capabilities.

• get_project_structure — returns the relevant structure of an OpenPLC Editor project.

• list_pous — lists programs, function blocks, and functions using the current OpenPLC Editor project layout.

OpenPLC project inspection follows the current Editor layout: project.json at the project root, POUs below pous/programs, pous/function-blocks, and pous/functions, plus the related device and datatype locations used by the Editor.

Scope

This version is intentionally read-only and experimental. It does not include project modification, compilation, deployment, runtime control, variable forcing, authentication, HTTP transport, or unrestricted shell/filesystem access. Those capabilities should be added only when concrete requirements justify them.