ThinkPLC-MCP

ThinkPLC-MCP is a server designed to interface with SIEMENS PLC S7-1500/1200 using their JSON-RPC 2.0 API. It exposes API functionalities as MCP tools, enabling AI assistants and other MCP-compatible clients to interact with the PLC programmatically.

🔧 Features

• Connects to a SIEMENS PLC API (Webserver) endpoint
• Provides MCP tools for:
  • ✅ User authentication (`login`, `logout`, `ChangePassword-user`)
  • ✅ Check PLC connectivity (`ping`)
  • ✅ Retrieve user permissions via `Api-GetPermissions` after login
  • ✅ Get API version with `Api-Version`
  • ✅ List available API methods using `Api-Browse`
  • ✅ Retrieve structure information with `Api-GetQuantityStructures`
  • ✅ Get password security policies with `Api-GetPasswordPolicy`
  • ✅ Browse tags and metadata using `PlcProgram-Browse`
  • ✅ Read single variables via `PlcProgram-Read`
  • ✅ Write Boolean, Number, or String tags with `PlcProgram-Write-*`
  • ✅ Read the current CPU operating mode with `Plc-ReadOperatingMode`
  • ✅ Request a change of operating mode using `Plc-RequestChangeOperatingMode`
  • ✅ Read the CPU system time (`Plc-ReadSystemTime`)
  • ✅ Set the CPU system time (`Plc-SetSystemTime`)
  • ✅ Read available project languages (`Project-ReadLanguages`)
  • ✅ Browse active alarms (`Alarms-Browse`)
  • ✅ Acknowledge alarms (`Alarms-Acknowledge`)
  • ✅ Browse diagnostic buffer entries (`DiagnosticBuffer-Browse`)
• 🔄 Optional: automatic service account login with token refresh

⚙️ Prerequisites

• Node.js (v18.x or later recommended)
• npm (comes bundled with Node.js)
• Access to a running SIEMENS PLC API (Webserver)

⚙️ Configuration

This server uses a `config.js` file written in ES Module syntax.

Example `config.js`:

export const config = {
  URL: "https:///api/jsonrpc", // required
  userName: "your-username", // optional
  pwr: "your-password", // optional
};

🚀 Getting Started

1. Navigate to the project folder:

cd your-project-directory

2. Install dependencies:

npm install

3. Edit config.js as shown above.

4. Start the server

node start

🖥️ Connecting with Claude Desktop

To use this MCP server with Claude AI (desktop version):

1. Find or create the claude_desktop_config.json file

(typically in the Claude app config folder).

2. Add or update the following:

{
  "mcpServers": {
    "ThinkPLC-MCP": {
      "command": "npx",
      "args": ["mcp-remote", "http://localhost:5000/mcp"]
    }
  }
}

4. Ensure @modelcontextprotocol/tools is installed:

npm install -g @modelcontextprotocol/tools