serial-out

Overview

The serial-out node writes data to a serial (UART) port. It sends commands and data to devices like Arduino boards, LCD displays, motor controllers, and industrial equipment over RS-232, RS-485, or USB-to-serial adapters. Supports string, byte array, and auto-converted data formats with optional newline appending.

Properties

Data Format

The node reads msg.payload.data and handles multiple input types automatically.

Example: Send Commands to Arduino

Send LED control commands to an Arduino board over USB serial.

// serial-out node configuration
{
  "port": "/dev/ttyACM0",
  "baudRate": 9600,
  "dataBits": 8,
  "stopBits": 1,
  "parity": "none",
  "addNewline": true
}

// Input msg from inject or function node:
{
  "payload": {
    "data": "LED_ON:13"
  }
}

// Sent to Arduino: "LED_ON:13\n"
// Arduino sketch reads with Serial.readStringUntil('\n')

// Example flow:
// [inject "LED_ON:13"] → [serial-out /dev/ttyACM0]
// [dashboard slider] → [function] → [serial-out]

Example: Serial LCD Display

Send text to a serial-connected LCD display for real-time status updates.

// serial-out node configuration
{
  "port": "/dev/ttyUSB0",
  "baudRate": 9600,
  "addNewline": false
}

// Function node formats display text:
// msg.payload = {
//   data: "Temp: " + msg.payload.temperature + "C"
// };
// return msg;

// For multi-line LCD:
// Line 1: "\xFE\x80" + "Temp: 23.5C"
// Line 2: "\xFE\xC0" + "Hum:  65.2%"

// Flow: [sensor] → [function format] → [serial-out LCD]

Example: Modbus RTU Command

Send a Modbus RTU read request to an industrial sensor over RS-485.

// serial-out node configuration
{
  "port": "/dev/ttyUSB1",
  "baudRate": 19200,
  "dataBits": 8,
  "stopBits": 1,
  "parity": "even",
  "addNewline": false
}

// Function node builds Modbus RTU frame:
// const addr = 0x01;       // Device address
// const func = 0x03;       // Read holding registers
// const reg = 0x0000;      // Starting register
// const count = 0x0002;    // Number of registers
// msg.payload = {
//   data: Buffer.from([addr, func,
//     (reg >> 8), (reg & 0xFF),
//     (count >> 8), (count & 0xFF)])
// };
// // CRC would be appended by protocol handler

// Flow: [inject trigger] → [function build frame] → [serial-out RS-485]
//       [serial-in RS-485] → [function parse response] → [dashboard]

Common Use Cases