wago-plc-mcp-server

MCP server that connects WAGO PLCs to LLM agents via the WDx/WDA REST API.

Ask an AI assistant to read sensor values, change configuration, trigger firmware updates, or monitor entire PLC fleets — with no custom code.

Claude Desktop / OpenClaw / any MCP client
        │  stdio or Streamable HTTP
        ▼
wago-plc-mcp-server  (Docker, port 6042)
        │  HTTPS / WDA REST API
        ▼
WAGO PLC fleet  (PFC200, PFC300, CC100, Edge Controller)

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Supported Hardware

Device	Notes
PFC200 Gen 2	Full support
PFC300	Full support
CC100	Full support — set WAGO_TIMEOUT_SECONDS=45 (slow ARM CPU)
Edge Controller	Full support — Docker and CODESYS runtime visible via WDA

Requires firmware ≥ 03.x with WDx/WDA REST API enabled. Tested up to firmware 04.09.01.

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Features

• 13 MCP tools — discover, read, write, invoke methods, monitor
• Fleet-wide parallel reads — query one parameter across all PLCs in a single tool call
• Server-side watchlists — efficient repeated polling without repeated handshakes
• Enum resolution — raw integer enum values translated to human-readable labels
• Writeability pre-validation — read-only parameters rejected before hitting the PLC
• Fuzzy parameter search — find parameters by keyword without knowing exact IDs
• Dual transport — Streamable HTTP (default) or SSE, switched via env var
• Docker-first — single container, host networking for routed PLC subnets

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Quick Start

1. Clone and configure

git clone https://github.com/your-username/wago-plc-mcp-server.git
cd wago-plc-mcp-server
cp _env .env

Edit .env:

WAGO_PLC_HOSTS=192.168.1.10,192.168.1.11,192.168.1.12
DEFAULT_PLC_USERNAME=admin
DEFAULT_PLC_PASSWORD=wago
TRANSPORT=streamable-http
PORT=6042
WAGO_TIMEOUT_SECONDS=15     # use 45 for CC100

2. Start

docker compose up -d
docker logs wmcp -f

Expected output:

Registration: 3/3 ready
MCP server listening on http://0.0.0.0:6042/mcp (Streamable HTTP)
StreamableHTTP session manager started

3. Verify

curl -X POST http://localhost:6042/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","method":"initialize","params":{"protocolVersion":"2025-11-25","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}},"id":1}'

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Connecting to Claude Desktop (Windows)

Claude Desktop requires a local stdio proxy. Install prerequisites on Windows:

python -m pip install fastmcp

Create wago_proxy.py:

from fastmcp import FastMCP, Client
from fastmcp.server import create_proxy

client = Client("http://<MCP_SERVER_IP>:6042/mcp")
mcp = create_proxy(client, name="wago-plc")
mcp.run(transport="stdio")

Add to %APPDATA%\Claude\claude_desktop_config.json:

{
  "mcpServers": {
    "wago-plc": {
      "command": "python",
      "args": ["C:\\path\\to\\wago_proxy.py"]
    }
  }
}

Fully quit and relaunch Claude Desktop. A hammer icon appears with the tool count.

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Connecting to OpenClaw / other agents

Point directly at the SSE or Streamable HTTP endpoint:

TRANSPORT=sse   # for OpenClaw

OpenClaw config:

{
  "mcpServers": {
    "wago-plc": {
      "type": "url",
      "url": "http://<MCP_SERVER_IP>:6042/sse"
    }
  }
}

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Tool Reference

Discovery

Tool	Description
list_plcs	List all registered PLC IPs
describe_plc(plc_ip)	Capability counts + feature names (cached, no network call)

Parameters

Tool	Description
find_parameters(plc_ip, query, writeable_only, user_settings_only, limit)	Search by keyword
get_parameter(plc_ip, parameter_id)	Read one value, enum labels resolved
get_parameters_bulk(requests)	Read one param from N PLCs in parallel
set_parameters(plc_ip, parameters)	Write one or more parameters (bulk PATCH)

Methods

Tool	Description
find_methods(plc_ip, query, limit)	Search by keyword
get_method(plc_ip, method_id)	Fetch inArgs/outArgs schema
invoke_method(plc_ip, method_id, arguments, wait)	Execute (sync or async)
get_method_run(plc_ip, method_id, run_id)	Poll async run status

Watchlists

Tool	Description
create_watchlist(plc_ip, parameter_ids, timeout_seconds)	Create server-side monitoring list
read_watchlist(plc_ip, watchlist_id)	Read current values (resets timeout)
delete_watchlist(plc_ip, watchlist_id)	Free watchlist before timeout

Example workflows

Read firmware version from all PLCs in one call:

get_parameters_bulk([
  {"plc_ip": "192.168.1.10", "parameter_id": "0-0-version-firmwareversion"},
  {"plc_ip": "192.168.1.11", "parameter_id": "0-0-version-firmwareversion"}
])

Sync NTP time on a PLC:

find_methods("192.168.1.10", "ntp")
→ ["0-0-ntpclient-updatetime"]

invoke_method("192.168.1.10", "0-0-ntpclient-updatetime", wait=True)
→ {"status": "done", "run_id": "1", "out_args": {}}

Monitor IO values repeatedly:

create_watchlist("192.168.1.10", ["param-a", "param-b"], timeout_seconds=300)
→ {"watchlist_id": "1", "parameters": [...]}

read_watchlist("192.168.1.10", "1")   # call repeatedly
delete_watchlist("192.168.1.10", "1") # cleanup

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Configuration Reference

Variable	Default	Description
WAGO_PLC_HOSTS	—	Comma-separated PLC IPs
DEFAULT_PLC_USERNAME	admin	Shared username
DEFAULT_PLC_PASSWORD	wago	Shared password
PLC_PASSWORDS_<ip_with_underscores>	—	Per-PLC password override
TRANSPORT	streamable-http	streamable-http or sse
HOST	0.0.0.0	Bind address
PORT	6042	Listen port
WAGO_TIMEOUT_SECONDS	10	Per-PLC HTTP timeout (use 45 for CC100)
WAGO_PAGE_LIMIT	500	Pagination page size
WAGO_MAX_CONCURRENT_REGISTRATIONS	5	Parallel PLC init limit
LOG_LEVEL	INFO	DEBUG / INFO / WARNING / ERROR
LOG_FILE	/app/mcp_server.log	Log file path inside container

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Building

# Dev build (patch version bump)
./build.sh --patch

# Build and start immediately
./build.sh --patch --start

# Release and push to Docker Hub
./build.sh --release

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Networking

The container uses network_mode: host by default. This is required when PLCs are on routed subnets not directly reachable from a bridged Docker network.

If your PLCs are on the same subnet as the Docker host and you prefer bridge networking, edit docker-compose.yml:

# Comment out:
# network_mode: host

# Uncomment:
ports:
  - "6042:6042"
networks:
  - wago-net

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Requirements

• Docker 24+ with Compose v2
• WAGO PLC with WDx/WDA REST API enabled (firmware ≥ 03.x)
• Network route from Docker host to PLC subnets

For Claude Desktop proxy: Python 3.11+ and fastmcp on the client machine.

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License

MIT