Node-RED MC Protocol Read

中文文档 | English

This is a Node-RED component designed for PLCs that communicate over Ethernet using the MC Protocol. A single node supports reading data from multiple PLC addresses at once.

Features

• Multiple Communication Modes: TCP protocol, Binary/ASCII mode, 1E/3E/4E frame formats
• Multi-address Reading: Read data from multiple PLC addresses simultaneously
• High Performance: Built-in queue mechanism to prevent concurrent read conflicts
• Flexible Output: JSON object or array format output
• Real-time Status: Visual connection status indicator
• Multi-language Support: Chinese and English interface support

System Requirements

Software Requirements

This program runs within Node-RED. Therefore, Node-RED and its runtime environment Node.js must be installed.

Supported PLC Models

This component uses the plcpeople/mcprotocol library for communication. PLCs supported by this library can be used. Due to equipment limitations, testing has only been conducted on AMX-FX3U-M26MR series PLCs.

Installation

Using Node-RED Palette Manager

1. Open Node-RED in your browser
2. Go to the menu (≡) and select "Manage palette"
3. Click the "Install" tab
4. Search for @yihengnp/node-red-mcprotocol-read
5. Click "Install"

Using npm Command

cd ~/.node-red
npm install @yihengnp/node-red-mcprotocol-read

Restart Node-RED after installation.

Example Flows

Example flows can be found in the examples folder of the node repository.

Output Format

JSON Format

{
  "timestamp": 1640995200000,
  "topic": "mc-read",
  "payload": {
    "D8470.0,8":[false,false,false,true,false,true,false,true],
    "D8470.8,8":[false,false,false,false,false,false,true,true]
  }
}

Array Format

{
  "timestamp": 1640995200000,
  "topic": "mc-read",
  "payload": [
    {"D8470.0,8":[false,false,false,true,false,true,false,true]},
    {"D8470.8,8":[false,false,false,false,false,false,true,true]}
  ]
}

Error Handling

Error Handling Modes

1. Throw Exception: Errors are thrown to Node-RED's debug panel
2. Message Mode: Errors are included in the output message

Error Message Format

{
  "timestamp": 1640995200000,
  "topic": "mc-read",
  "error": "An error occurred while reading values from plc: Connection timeout",
  "payload": null
}

Contributing

All contributions are welcome! Whether it’s a bug fix, new feature, or documentation improvement, feel free to open a pull request or issue.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Related Projects

• mcprotocol - This component uses this library to communicate with PLCs