🏭 WMind Edge Gateway — ESP32 → OPC UA Bridge

A real-time industrial IoT pipeline that streams live sensor data from an ESP32 device directly into an OPC UA Server — with zero-config UDP auto-discovery, multi-gateway TCP streaming, and a fully structured plant address space.

📐 System Architecture

┌──────────────────────────────────────┐         ┌─────────────────────────────────────────────┐
│            ESP32 Device              │         │         WMind Gateway  (Windows / Linux)    │
│                                      │         │                                             │
│  🌡  DS18B20 Temp Sensor  (GPIO 14)  │         │  ┌─────────────────────────────────────┐    │
│  🔄  Rotary Encoder (GPIO 18 / 19)  │         │  │   UDP Discovery Service  :8888      │    │
│                                      │  UDP    │  │   "WHO_IS_GATEWAY?" ←→ Reply        │    │
│  1. Broadcasts WHO_IS_GATEWAY?       │────────▶│  └─────────────────────────────────────┘   │
│  2. Receives gateway IP + Port       │◀────────│                                            │
│                                      │         │  ┌─────────────────────────────────────┐   │
│  3. Opens TCP connection             │  TCP    │  │   TCP Server  :9000                 │   │
│  4. Streams JSON every 1 second      │────────▶│  │   JSON → Parse → OPC UA Nodes       │   │
│                                      │         │  └─────────────────────────────────────┘   │
└──────────────────────────────────────┘         │                                            │
                                                 │  ┌─────────────────────────────────────┐   │
                                                 │  │   OPC UA Server  :4840              │   │
                                                 │  │   opc.tcp://localhost:4840/         │   │
                                                 │  │             WMindGateway            │   │
                                                 │  └─────────────────────────────────────┘   │
                                                 └─────────────────────────────────────────────┘

📂 Project Structure

opc_ua/
│
├── src/                            # ESP32 PlatformIO firmware
│   └── main.cpp                    # WiFi, UDP discovery, TCP client, sensors
│
├── include/                        # PlatformIO headers
├── lib/                            # PlatformIO local libraries
├── test/                           # PlatformIO tests
├── platformio.ini                  # Board + library config for ESP32
├── .gitignore
│
└── server/                         # .NET OPC UA Gateway Server
    ├── Program.cs                  # Entry point — bootstraps OPC UA + discovery
    ├── SimulatorServer.cs          # Subclasses StandardServer, wires NodeManager
    ├── SimulatorNodeManager.cs     # Builds OPC UA address space + TCP ingestion
    ├── GatewayDiscoveryService.cs  # UDP responder — tells ESP32 "I'm here"
    ├── OpcUaSimulator.csproj       # .NET project file
    ├── simulator.sln               # Solution file
    ├── appsettings.json
    └── pki/                        # Auto-generated OPC UA certificates

⚙️ How It Works

1 — ESP32 Firmware (`src/main.cpp`)

On boot, the ESP32:

Connects to WiFi
Broadcasts WHO_IS_GATEWAY? over UDP port 8888 (subnet-wide)
Receives I_AM_GATEWAY:<ip>:<port> replies and connects to all discovered gateways via TCP (supports up to 5 simultaneous gateways)
Reads real temperature every second from a DS18B20 one-wire sensor on GPIO 14
Simulates voltage (15.0V – 30.0V) via a rotary encoder — each detent click = ±0.1V
Serializes both signals as JSON and streams to all gateways every second

JSON payload streamed by ESP32:

{
  "deviceId": "ESP32_01",
  "timestamp": 12453,
  "ns=2;s=Plant=MUMBAI_PLANT/Line=ASSEMBLY_01/Machine=CNC_02/Signal=VOLTAGE": 24.3,
  "ns=2;s=Plant=MUMBAI_PLANT/Line=ASSEMBLY_01/Machine=CNC_02/Signal=TEMP": 31.7
}

2 — Gateway Server (`server/`)

File	Role
`GatewayDiscoveryService.cs`	Listens on UDP `8888`. Replies with its own WiFi IP + TCP port so ESP32 auto-discovers it — no hardcoded IPs needed
`SimulatorNodeManager.cs`	TCP server on port `9000`. Accepts multiple ESP32 clients, parses JSON, writes values into live OPC UA nodes
`SimulatorServer.cs`	Wires the custom node manager into the standard OPC UA server stack
`Program.cs`	Validates certificates, starts UDP + TCP + OPC UA, prints the endpoint

3 — OPC UA Address Space

Once running, the server exposes this live node hierarchy:

Objects/
└── 📁 MUMBAI_PLANT
    └── 📁 ASSEMBLY_01
        └── 📁 CNC_02
            ├── 📊 VOLTAGE   (Double — updated live every second)
            └── 🌡 TEMP      (Double — updated live every second)

OPC UA Endpoint:

opc.tcp://localhost:4840/WMindGateway

Node IDs for direct browsing or subscription:

ns=2;s=Plant=MUMBAI_PLANT/Line=ASSEMBLY_01/Machine=CNC_02/Signal=VOLTAGE
ns=2;s=Plant=MUMBAI_PLANT/Line=ASSEMBLY_01/Machine=CNC_02/Signal=TEMP

🔌 Hardware Wiring

Component	ESP32 Pin	Notes
DS18B20 Data	GPIO 14	Add 4.7kΩ pull-up to 3.3V
DS18B20 VCC	3.3V
DS18B20 GND	GND
Rotary CLK	GPIO 18	Internal pull-up enabled in code
Rotary DT	GPIO 19	Internal pull-up enabled in code
Rotary GND	GND

🛠️ Prerequisites

For ESP32 Firmware:

VS Code + PlatformIO Extension

For Gateway Server:

.NET 8 SDK or later

⚠️ Both the PC running the gateway and the ESP32 must be connected to the same WiFi network.

🚀 Getting Started

Step 1 — Clone the Repository

git clone https://github.com/your-username/opc-ua-esp32.git
cd opc-ua-esp32

Step 2 — Configure WiFi Credentials

Open src/main.cpp and update these two lines with your network details:

const char* ssid     = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";

Make sure the PC running the gateway server is on the same WiFi network as the ESP32.

Step 3 — Start the OPC UA Gateway Server First

Open a terminal, navigate to the server folder, and run:

cd server
dotnet run

You should see:

🔎 UDP Discovery Service running on port 8888
📡 TCP Gateway Listening on port 9000
✅ WMind OPC UA Gateway Running
📡 OPC UA Endpoint: opc.tcp://localhost:4840/WMindGateway
📡 TCP Server Port: 9000
Press ENTER to stop...

Start the server before powering the ESP32 so it can discover the gateway on boot.

Step 4 — Upload Firmware to ESP32

Open the opc_ua/ root folder in VS Code with PlatformIO, then upload using either:

PlatformIO toolbar — click the → Upload (right arrow) button

or terminal:

pio run --target upload

Step 5 — Monitor Serial Output

After uploading, open the serial monitor at 115200 baud:

pio device monitor --baud 115200

Expected output on the ESP32 serial monitor:

Connecting to WiFi....
WiFi connected
ESP32 IP: 192.168.1.105
Searching for Gateways...
Reply: I_AM_GATEWAY:192.168.1.10:9000
Gateway Found: 192.168.1.10:9000
Connected → 192.168.1.10
Sent → 24.30 V | 31.70 °C → 1 gateways
Sent → 24.30 V | 31.72 °C → 1 gateways

And back in the server terminal you will see:

🔌 ESP32 Connected: 192.168.1.105:54321
⚡ OPC UA Updated → V=24.30V | T=31.70°C
⚡ OPC UA Updated → V=24.30V | T=31.72°C

📡 Connecting an OPC UA Client

Use any OPC UA client — UaExpert, Prosys OPC UA Browser, Node-RED, or your own application — and connect to:

opc.tcp://localhost:4840/WMindGateway

Then browse or subscribe to these node IDs for live data:

Signal	Node ID
Voltage	`ns=2;s=Plant=MUMBAI_PLANT/Line=ASSEMBLY_01/Machine=CNC_02/Signal=VOLTAGE`
Temperature	`ns=2;s=Plant=MUMBAI_PLANT/Line=ASSEMBLY_01/Machine=CNC_02/Signal=TEMP`

Values update every 1 second as data arrives from the ESP32.

🔧 Configuration Reference

Parameter	Default Value	Location
WiFi SSID	Edit in firmware	`src/main.cpp`
UDP Discovery Port	`8888`	ESP32 + Server
TCP Data Port	`9000`	ESP32 + Server
OPC UA Port	`4840`	`Program.cs`
Max Gateways	`5`	`src/main.cpp`
Voltage Range	`15.0V – 30.0V`	`src/main.cpp`
Encoder Step	`0.1V per click`	`src/main.cpp`
Temp Sensor Pin	`GPIO 14`	`src/main.cpp`
Rotary CLK Pin	`GPIO 18`	`src/main.cpp`
Rotary DT Pin	`GPIO 19`	`src/main.cpp`

📦 PlatformIO Library Dependencies

Defined in platformio.ini and auto-installed by PlatformIO:

lib_deps =
    bblanchon/ArduinoJson
    milesburton/DallasTemperature
    paulstoffregen/OneWire

📦 .NET NuGet Dependencies

Restored automatically on dotnet run:

<PackageReference Include="OPCFoundation.NetStandard.Opc.Ua" Version="1.5.374.118" />
<PackageReference Include="OPCFoundation.NetStandard.Opc.Ua.Server" Version="1.5.374.118" />

🔒 OPC UA Security Notes

Certificates are auto-generated on first run inside server/pki/
AutoAcceptUntrustedCertificates = true is set for easy development
For production use: disable auto-accept and configure proper certificate trust
To expose the server on your local network, replace localhost in the endpoint with your machine's actual IP address

🧯 Troubleshooting

Problem	Solution
`No gateways found` on ESP32	Start the server before the ESP32 boots, or press the ESP32 reset button after the server is up
Server can't find WiFi IP	`GatewayDiscoveryService` only reads Wireless interfaces — connect your PC to WiFi, not Ethernet
OPC UA client can't connect	Allow port `4840` TCP inbound through Windows Firewall
DS18B20 reads `-127°C`	Check wiring and confirm 4.7kΩ pull-up resistor between GPIO 14 and 3.3V
Certificate error on startup	Delete the `server/pki/` folder and restart — it will regenerate
Multiple gateways not connecting	Ensure each gateway server is running and on the same subnet

Built with ❤️ using ESP32 · PlatformIO · .NET 8 · OPC UA

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Repository files navigation

🏭 WMind Edge Gateway — ESP32 → OPC UA Bridge

📐 System Architecture

📂 Project Structure

⚙️ How It Works

1 — ESP32 Firmware (`src/main.cpp`)

2 — Gateway Server (`server/`)

3 — OPC UA Address Space

🔌 Hardware Wiring

🛠️ Prerequisites

🚀 Getting Started

Step 1 — Clone the Repository

Step 2 — Configure WiFi Credentials

Step 3 — Start the OPC UA Gateway Server First

Step 4 — Upload Firmware to ESP32

Step 5 — Monitor Serial Output

📡 Connecting an OPC UA Client

🔧 Configuration Reference

📦 PlatformIO Library Dependencies

📦 .NET NuGet Dependencies

🔒 OPC UA Security Notes

🧯 Troubleshooting

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server		server
src		src
test		test
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README.md		README.md
platformio.ini		platformio.ini

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🏭 WMind Edge Gateway — ESP32 → OPC UA Bridge

📐 System Architecture

📂 Project Structure

⚙️ How It Works

1 — ESP32 Firmware (src/main.cpp)

2 — Gateway Server (server/)

3 — OPC UA Address Space

🔌 Hardware Wiring

🛠️ Prerequisites

🚀 Getting Started

Step 1 — Clone the Repository

Step 2 — Configure WiFi Credentials

Step 3 — Start the OPC UA Gateway Server First

Step 4 — Upload Firmware to ESP32

Step 5 — Monitor Serial Output

📡 Connecting an OPC UA Client

🔧 Configuration Reference

📦 PlatformIO Library Dependencies

📦 .NET NuGet Dependencies

🔒 OPC UA Security Notes

🧯 Troubleshooting

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1 — ESP32 Firmware (`src/main.cpp`)

2 — Gateway Server (`server/`)

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