OPCUA2MCP IIoT Bridge

This repository provides an end-to-end Industrial IoT prototype that converts OPC UA sensor data into MCP-compatible tools and exposes machine health via both HTTP and MCP.

What is opcua2mcp?

opcua2mcp is the core bridge module in src/opcua2mcp.py. It connects to an OPC UA server, reads sensor values defined in YAML configuration, evaluates sensor health against configurable thresholds, caches readings, and publishes the results through a FastMCP server.

The design is ideal for IIoT deployments that need:

• OPC UA data ingestion from equipment simulators or real PLCs

• MCP tool exposure for model context interoperability

• machine health scoring and alert generation

• optional Redis caching for faster repeated reads

Architecture

• app/app.py — start-up script that loads app/config.yaml, reads environment variables, and launches the converter.

• src/opcua2mcp.py — core converter implementation that builds the MCP server and sensor health logic.

• app/opcua_simulator.py — OPC UA simulator that can be configured from YAML and serves variable sensor values.

• docker-compose.yml — orchestrates the OPC UA simulator, two machine-specific converter containers, and Redis.

Configuration

The OPC UA simulator and sensor definitions are stored in app/config.yaml. Example structure:

server:
  endpoint: opc.tcp://0.0.0.0:4840
  namespace: http://opcua.simulator
  update_interval: 2

machines:
  Machine-001:
    vibration:
      node_id: ns=2;s=Machine-001/Device/Vibration
      unit: mm/s
      threshold: 3.5
      initial_value: 2.2
      min: 0.5
      max: 5.0
      step: 0.25
      randomize: true
    temperature:
      node_id: ns=2;s=Machine-001/Device/Temperature
      unit: C
      threshold: 80.0
      initial_value: 68.0
      min: 50.0
      max: 92.0
      step: 1.5
      randomize: true

Each machine has named sensors with:

• node_id or generated node identifier

• unit

• threshold for health evaluation

• optional simulation parameters: initial_value, min, max, step, randomize

Running the stack

Install dependencies:

pip install -r requirements.txt

Run with Docker Compose:

docker compose up --build

This brings up:

• opcua-simulator exposing OPC UA on 4840

• opcua2mcp_001 exposing MCP and HTTP on 5011

• opcua2mcp_002 exposing MCP and HTTP on 5021

• redis for cache storage

Environment variables

app/app.py supports the following environment variables:

• MACHINE_NAME — machine name from YAML config (Machine-001, Machine-002)

• OPCUA_ENDPOINT — OPC UA server URL

• CACHE_BACKEND — memory or redis

• REDIS_URL — Redis connection URL

• CACHE_TTL — seconds to keep cached sensor results

• MCP_PORT — internal HTTP/MCP service port

• OPCUA_CONFIG — path to the YAML config file

API Reference

MCP Exposure

src/opcua2mcp.py registers two MCP tools via FastMCP:

1. health.check

   • title: Machine Health Check

   • returns current machine health, score, alerts, and sensor readings

2. read.sensors

   • title: Read All Sensors

   • returns the latest sensor values for the configured machine

These tools are available through the MCP /mcp endpoint supported by FastMCP.

HTTP Routes

In addition to the MCP tools, opcua2mcp exposes three HTTP endpoints on the same service port:

• GET /health

  • returns the current health status for the machine

  • fields include: machine_name, status, health_score, alerts, total_sensors, sensor_readings, timestamp

• GET /sensors

  • returns latest sensor values and status for every configured sensor

  • this forces a fresh read from OPC UA before replying

• GET /cache

  • returns the current cache contents

  • includes cached sensor readings stored in memory or Redis

Example HTTP usage

curl http://localhost:5011/health
curl http://localhost:5011/sensors
curl http://localhost:5011/cache

Why opcua2mcp?

This bridge is designed to sponsor MCP adoption by demonstrating a real IIoT use case:

• converting OPC UA telemetry into MCP tool semantics

• evaluating machine health automatically

• exposing both standard HTTP and MCP-compatible interfaces

• enabling multi-machine deployments with one YAML-driven config

Extending the bridge

You can extend src/opcua2mcp.py by:

• adding new MCP tools for individual sensor reads

• enriching health logic with custom scoring rules

• adding additional OPC UA namespaces or node discovery

• supporting more machine types in app/config.yaml

Important files

• src/opcua2mcp.py — main converter and MCP server definition

• app/app.py — launch script and environment-driven startup

• app/opcua_simulator.py — OPC UA simulator service

• app/config.yaml — sensor and simulator configuration

• docker-compose.yml — multi-service orchestration

Notes

The MCP bridge uses FastMCP from the official mcp package, and the simulator uses opcua to host realistic sensor variables.

For development, run the stack locally and inspect the /health, /sensors, and /cache endpoints for immediate visibility into the OPC UA → MCP workflow.