PLCGateway MCP

MCP server for PLCs, CNC machines and SCADA. Ask an AI assistant about live machine data, alarms, history and OEE, and let it add devices, tags, screens and reports, on your own network.

PLCGateway is PLC gateway and SCADA software: it connects PLCs, CNC machines and controllers (Siemens S7, Modbus, Mitsubishi, Omron, Allen-Bradley, FANUC, OPC UA and more) and shares their data over OPC UA, MQTT, Modbus TCP and REST. Every PLCGateway product has an MCP server built in. This package is a small stdio bridge: MCP clients that start servers as a command (Claude Desktop, Claude Code, Cursor, Cline, Windsurf, …) run it, and it forwards everything to your PLCGateway on your network.

AI client ──stdio──▶ @plcgateway/mcp ──HTTP (your network)──▶ PLCGateway on your premises ──▶ PLCs & machines

PLCGateway runs on your premises. The bridge talks only to the address you give it; it collects nothing and sends nothing elsewhere.
The assistant works with the rights of the token you give it, the same roles as people.

What you can ask

"How many alarms did line 3 have in the last 2 hours?"
"What was the filler's OEE today, and where did we lose the most time?"
"Summarise the last 24 hours of the tank level trend."
"Build a report dashboard with production and energy per shift for line 1." (draft for you to review)
"Add the Modbus TCP meter at 192.168.1.40 as 'Compressor 2 energy meter'." (needs the MCP configuration token)

Tools

The tools come from the PLCGateway you connect to, so the list follows your edition and the rights of your token.

Group	Tools
Context	`get_site_context`, `system_status`, `help`, `list_protocols`
Data	`list_devices`, `list_tags`, `read_tags`, `query_history`, `write_tag`
Alarms	`active_alarms`, `alarm_history`, `alarm_stats`, `acknowledge_alarm`, `list_alarm_definitions`
Production	`calculate_oee`, `get_production_kpis`, `list_production_assets`, `list_batches`, `list_production_batches`, `set_batch_result`
Screens and reports	`list_screens`, `get_screen`, `list_symbols`, `create_screen_draft`, `create_dashboard_draft`, `generate_report`
Configuration (admin)	`set_site_profile`, `test_device`, `create_device`, `update_device`, `create_tags`, `update_tags`, `define_production_asset`, `define_products`, OPC UA certificate actions

Full description: https://plcgateway.com/ai-mcp

Supported devices and protocols

All drivers are included in every licence, with no device or tag limit:

Siemens S7 · Modbus TCP/RTU · Mitsubishi MC · Omron FINS · Allen-Bradley EtherNet/IP · Beckhoff ADS · FANUC FOCAS · OPC UA and DA · IEC 60870-5-104 · IEC 61850 · DNP3 · BACnet

Data goes out over an OPC UA server, MQTT, a Modbus TCP server and a REST API. Details: https://plcgateway.com/protocols

Safety

On your premises. PLCGateway sends nothing to a cloud by itself; tool results go only to the assistant you connect. With a self-hosted model the data stays in your network.
Same roles as people. Viewer, operator and administrator rights apply to the assistant. Writing a value needs operator rights; configuration needs an administrator session, a local connection or the configuration token.
Drafts, not live changes. Screens and dashboards an assistant creates are drafts that a person reviews.
Audit trail. Every write is logged with the user's name.

Requirements

PLCGateway SCADA or Connect, reachable from the computer running the AI client, with MCP enabled
An API token: PLCGateway → Settings → API token (operator rights: read, write, alarm acknowledgement)
Node.js 18.17 or newer

For setup work (adding devices and tags) create the MCP configuration token in Settings and switch it off when done.

Setup

Claude Desktop, Cursor, Cline and other stdio clients

{
  "mcpServers": {
    "plcgateway": {
      "command": "npx",
      "args": ["-y", "@plcgateway/mcp"],
      "env": {
        "PLCGATEWAY_URL": "http://192.168.1.50:8080",
        "PLCGATEWAY_TOKEN": "<your API token>"
      }
    }
  }
}

Claude Code

claude mcp add --transport stdio \
  --env PLCGATEWAY_URL=http://192.168.1.50:8080 \
  --env PLCGATEWAY_TOKEN=<your API token> \
  plcgateway -- npx -y @plcgateway/mcp

Clients that support HTTP MCP directly

You don't need this package; connect straight to PLCGateway:

{ "mcpServers": { "plcgateway": { "type": "http", "url": "http://192.168.1.50:8080/mcp",
                                   "headers": { "Authorization": "Bearer <your API token>" } } } }

On the PLCGateway computer itself

plcgateway-scada --mcp-stdio (or plcgateway-connect --mcp-stdio) can be added as the command directly.

Configuration

Variable	Flag	Description
`PLCGATEWAY_URL`	`--url`	PLCGateway address, e.g. `http://192.168.1.50:8080` (`/mcp` is added if missing)
`PLCGATEWAY_TOKEN`	`--token`	API token or MCP configuration token. Prefer the environment variable.
`PLCGATEWAY_TIMEOUT`	`--timeout`	Request timeout in seconds (default 120)

For HTTPS with your own certificate authority, set NODE_EXTRA_CA_CERTS=/path/to/ca.pem.

Troubleshooting

The bridge logs to stderr (visible in your client's MCP logs).

If PLCGateway cannot be reached when the client connects, the bridge stays up in offline mode with a single tool, connection_status. Ask the assistant "why is PLCGateway not connected?" and it reports the reason. The bridge retries by itself, and the plant tools appear once PLCGateway answers.

Message	What to check
`PLCGateway not reachable`	Address and port, firewall, PLCGateway running
`HTTP 401/403`	The token (Settings → API token); a regenerated token replaces the old one
`HTTP 404`	MCP is disabled in PLCGateway settings, or the URL points elsewhere

Getting PLCGateway

30-day trial of every product and module, no licence needed: https://plcgateway.com/contact
Pricing: one-time licence per computer, MCP server included in every edition: https://plcgateway.com/pricing

License

The bridge in this repository is MIT licensed. PLCGateway itself is proprietary software, licensed separately.

plcgateway

Documentation