WinCC OA MCP Server

A Model Context Protocol (MCP) server that exposes WinCC OA datapoint operations as LLM-callable tools. It runs inside a WinCC OA Node.js Manager and uses the native winccoa-manager add-on to interact with the WinCC OA runtime.

Features

Tool	Description	Hint
`winccoa_dp_get`	Read one or more datapoint element values	read-only
`winccoa_dp_set`	Write values (fire-and-forget or confirmed)	write
`winccoa_dp_create`	Create a new datapoint	write
`winccoa_dp_delete`	Delete a datapoint	destructive
`winccoa_dp_copy`	Copy a datapoint to a new name	write
`winccoa_dp_names`	List DPs matching a pattern	read-only
`winccoa_dp_exists`	Check whether a DP identifier exists	read-only
`winccoa_dp_query`	Run a WinCC OA SQL-like query	read-only
`winccoa_dp_types`	List datapoint types matching a pattern	read-only

Prerequisites

WinCC OA 3.20 (or compatible) with the Node.js Manager enabled
Node.js 18+ (bundled with WinCC OA or system-installed)
The winccoa-manager native add-on (provided by the WinCC OA runtime – not on npm)

Installation

cd winccoa-mcp-server
npm install
npm run build

This compiles TypeScript sources from src/ into dist/.

Configuration

Since the WinCC OA Node.js Manager does not support command-line arguments, all configuration is done through a .env file placed next to the built entry point (or in the working directory).

A default .env file is included in the repository:

# Transport mode: "stdio" or "http"
MCP_TRANSPORT=stdio

# Port for the HTTP transport (only used when MCP_TRANSPORT=http)
MCP_HTTP_PORT=47899

# Maximum response size in characters to prevent overwhelming the LLM context
MCP_CHARACTER_LIMIT=25000

Variable	Description	Default
`MCP_TRANSPORT`	`"stdio"` or `"http"`	`stdio`
`MCP_HTTP_PORT`	Port for HTTP transport	`47899`
`MCP_CHARACTER_LIMIT`	Max response length (chars)	`25000`

Usage

stdio transport (default)

The server communicates over stdin / stdout. Use this when the MCP client (e.g. Claude Desktop, VS Code) starts the process directly or when testing with MCP Inspector.

node dist/index.js

HTTP transport

Set MCP_TRANSPORT=http in your .env file, then start the server. It will listen on the port specified by MCP_HTTP_PORT.

node dist/index.js

Integration with WinCC OA

This server is designed to be run as customer code inside a WinCC OA Node.js Manager. The typical setup:

Place the built dist/ folder (or the whole project) in your WinCC OA project's scripts directory.
Configure a Node.js Manager in the WinCC OA console with this server as the entry script.
The WinCC OA bootstrap will load the native winccoa-manager add-on, then execute dist/index.js.

MCP client configuration

Claude Desktop (`claude_desktop_config.json`)

{
  "mcpServers": {
    "winccoa": {
      "command": "node",
      "args": ["C:/path/to/winccoa-mcp-server/dist/index.js"]
    }
  }
}

VS Code (`.vscode/mcp.json`)

{
  "servers": {
    "winccoa": {
      "type": "stdio",
      "command": "node",
      "args": ["C:/path/to/winccoa-mcp-server/dist/index.js"]
    }
  }
}

For HTTP transport, point the client to http://localhost:47899/mcp (or your configured port).

Development

# Run in development mode (tsx, no build step)
npm run dev

# Test with MCP Inspector
npm run inspect

To switch transports during development, edit the .env file.

Project structure

src/
├── index.ts                 # Entry point – transport setup
├── server.ts                # McpServer creation
├── constants.ts             # Shared constants
├── winccoa-client.ts        # WinccoaManager singleton
├── types/
│   └── winccoa-manager.d.ts # Type declarations for native add-on
├── tools/
│   ├── register-all.ts      # Tool registration orchestrator
│   ├── dp-get.ts            # winccoa_dp_get
│   ├── dp-set.ts            # winccoa_dp_set
│   ├── dp-create.ts         # winccoa_dp_create
│   ├── dp-delete.ts         # winccoa_dp_delete
│   ├── dp-copy.ts           # winccoa_dp_copy
│   ├── dp-names.ts          # winccoa_dp_names
│   ├── dp-exists.ts         # winccoa_dp_exists
│   ├── dp-query.ts          # winccoa_dp_query
│   └── dp-types.ts          # winccoa_dp_types
└── utils/
    ├── error-handler.ts     # WinCC OA error handling
    └── formatters.ts        # Response formatting helpers

Adding new tools

Create src/tools/your-tool.ts following the existing pattern (Zod schema + registerTool()).
Import and call your registration function in src/tools/register-all.ts.
Rebuild with npm run build.

License

MIT