MCP PLC Core 🏭

Universal MCP Server for industrial PLC communication — works with ANY PLC.

Connect any industrial controller to AI agents (Claude, GPT, OpenClaw) via MCP protocol. Siemens, Schneider, ABB, Mitsubishi, Omron, Allen-Bradley, WAGO, CODESYS, Arduino, ESP32, or any custom PLC — write an adapter and it just works.

Don't see your PLC? Write an adapter — takes 15 minutes. Just implement 6 methods in the PLCAdapter interface.

AI Agent (Claude, GPT, OpenClaw)
    ↓ MCP protocol (stdio)
MCP PLC Core
    ↓ your adapter (Modbus, S7, OPC UA, EtherNet/IP...)
PLC → Sensors, Alarms, Motors, Actuators

Quick Start

# Install
npm install mcp-plc-core

# Schneider / ABB / WAGO / CODESYS / Arduino
PLC_HOST=192.168.1.100 npx mcp-plc --adapter modbus

# Siemens S7-1200/1500/300/400
npm install nodes7
PLC_HOST=192.168.1.100 npx mcp-plc --adapter s7

# Mitsubishi / Omron / Allen-Bradley / anything else
npx mcp-plc --adapter ./my-custom-adapter.js

Built-in Adapters

Adapter	Protocol	Port	PLC Types
modbus	Modbus TCP	502	Schneider, ABB, WAGO, CODESYS, Arduino
s7	S7 (RFC1006)	102	Siemens S7-1200/1500/300/400

Custom Adapter — Works with ANY PLC

Implement the PLCAdapter interface for your PLC. Regardless of manufacturer, protocol, or model — if it has TCP/IP or serial connectivity, you can write an adapter.

PLCs you can write adapters for:

• Siemens S7-200/300/400/1200/1500/1700
• Schneider M340/M580/Modicon
• ABB AC500/AC580
• Mitsubishi MELSEC iQ-R/F/L
• Omron NJ/NX/NP
• Allen-Bradley ControlLogix/CompactLogix
• WAGO PFC200/750
• CODESYS-based controllers
• Bosch Rexroth IndraMotion
• Beckhoff TwinCAT
• Fanuc CNC (FOCAS)
• Haas / DMG Mori / Mazak
• Arduino + EthernetShield
• ESP32 + Modbus/S7 gateway
• Any custom TCP/UDP protocol

import { PLCAdapter, SensorData, AlarmData, StatusData, SetpointData, OutputData } from "mcp-plc-core";

export class MyPLCAdapter implements PLCAdapter {
  readonly name = "My PLC";
  readonly protocol = "my-protocol";

  async connect() { /* ... */ }
  async disconnect() { /* ... */ }
  isConnected(): boolean { /* ... */ }

  async readSensors(): Promise<SensorData> {
    return {
      temperature: 25.3,
      pressure: 6.2,
      motorSpeed: 1500,
      production: 1234,
    };
  }

  async readAlarms(): Promise<AlarmData> {
    return { active: [], count: 0 };
  }

  async readStatus(): Promise<StatusData> {
    return { status: "running" };
  }

  async readSetpoints(): Promise<SetpointData> {
    return { temperature: 25, pressure: 6, speed: 1500 };
  }

  async readOutputs(): Promise<OutputData> {
    return { green: true, yellow: false, red: false };
  }

  async writeSetpoint(parameter: string, value: number): Promise<boolean> {
    // Write to your PLC...
    return true;
  }
}

Then use it:

import { startServer, MyPLCAdapter } from "mcp-plc-core";

const adapter = new MyPLCAdapter();
await startServer({
  adapter,
  limits: {
    temperature: { min: 0, max: 50 },
    pressure: { min: 0, max: 10 },
  },
});

MCP AI Integration

Claude Desktop / OpenClaw

{
  "mcpServers": {
    "plc": {
      "command": "npx",
      "args": ["mcp-plc", "--adapter", "modbus"],
      "env": {
        "PLC_HOST": "192.168.1.100",
        "PLC_PORT": "502"
      }
    }
  }
}

Siemens S7

{
  "mcpServers": {
    "plc": {
      "command": "npx",
      "args": ["mcp-plc", "--adapter", "s7"],
      "env": {
        "PLC_HOST": "192.168.1.100",
        "PLC_SLOT": "1"
      }
    }
  }
}

Tools

Tool	Description	Example
read_sensor	Read sensor value	"What's the temperature?"
get_alarms	Get active alarms	"Any alarms active?"
get_status	Full system status	"How's the line running?"
get_setpoints	Current setpoints	"What are the setpoints?"
write_setpoint	Write setpoint (safe!)	"Set temperature to 35°C"
get_all	Everything at once	"Give me all data"

Resources

Resource	Description
plc://tags	Available sensors/tags
plc://alarms	Alarm definitions
plc://status	Current status
plc://info	PLC and adapter info

Safety

• ✅ Read-only by default — no writes without explicit tool call
• ✅ Safety limits — configurable min/max for setpoints
• ✅ Audit logging — all tool calls logged
• ✅ Adapter isolation — protocol-specific errors don't leak
• ⚠️ Write protection — only setpoint registers, never I/O directly

Architecture

src/
├── adapter.ts          ← PLCAdapter interface (implement this)
├── server.ts           ← MCP server (generic, adapter-agnostic)
├── cli.ts              ← CLI entry point
├── index.ts            ← Package exports
└── adapters/
    ├── modbus.ts       ← Modbus TCP adapter (built-in)
    └── s7.ts           ← Siemens S7 adapter (built-in)

Writing a New Adapter

6 methods. 15 minutes. Works with any PLC.

1. Create src/adapters/myplc.ts
2. Implement PLCAdapter interface (6 methods)
3. Register in cli.ts:

if (adapterName === "myplc") {
  const { MyPLCAdapter } = await import("./adapters/myplc.js");
  return new MyPLCAdapter({ host, port });
}

4. Submit PR! 🎉

Supported Protocols (via adapters)

Protocol	Status	Adapter
Modbus TCP	✅ Built-in	modbus
S7 (RFC1006)	✅ Built-in	s7
OPC UA	✅ Via community	node-opcua
EtherNet/IP	✅ Via community	ethernetip
BACnet	✅ Via community	bacstack
MQTT + Sparkplug B	✅ Via community	mqtt
Mitsubishi MC Protocol	🔨 Community needed	—
Omron FINS	🔨 Community needed	—
Allen-Bradley CIP	🔨 Community needed	—
Bosch Rexroth	🔨 Community needed	—
Fanuc FOCAS	🔨 Community needed	—
Haas NGC	🔨 Community needed	—
Any custom TCP/UDP	✅ Adapter interface	PLCAdapter

Don't see your protocol? Implement PLCAdapter — 6 methods, 15 minutes of work. Submit a PR and it'll be in the next release.

Environment Variables

Variable	Default	Description
PLC_HOST	127.0.0.1	PLC IP address
PLC_PORT	varies	PLC port (502 for Modbus, 102 for S7)
PLC_ADAPTER	modbus	Adapter to use
PLC_RACK	0	Rack number (S7 only)
PLC_SLOT	1	Slot number (S7: 1, S7-300/400: 2)

License

MIT — use it, fork it, build adapters for your PLC.

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HD WebDesign — MCP for industrial automation