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

# 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

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;
  }
}

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 },
  },
});

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

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

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)

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