Version: 7.x.x

SerialPort Usage

const SerialPort = require('serialport')
const port = new SerialPort('/dev/tty-usbserial1', {
baudRate: 57600
})

When opening a serial port, specify (in this order)

  1. Path to Serial Port - required.
  2. Options - optional and described below.

Constructing a SerialPort object immediately opens a port. While you can read and write at any time (it will be queued until the port is open), most port functions require an open port. There are three ways to detect when a port is opened.

  • The open event is always emitted when the port is opened.
  • The constructor's openCallback is passed to .open(), if you haven't disabled the autoOpen option. If you have disabled it, the callback is ignored.
  • The .open() function takes a callback that is called after the port is opened. You can use this if you've disabled the autoOpen option or have previously closed an open port.
const SerialPort = require('serialport')
const port = new SerialPort('/dev/tty-usbserial1')
port.write('main screen turn on', function(err) {
if (err) {
return console.log('Error on write: ', err.message)
}
console.log('message written')
})
// Open errors will be emitted as an error event
port.on('error', function(err) {
console.log('Error: ', err.message)
})

Detecting open errors can be moved to the constructor's callback.

const SerialPort = require('serialport')
const port = new SerialPort('/dev/tty-usbserial1', function (err) {
if (err) {
return console.log('Error: ', err.message)
}
})
port.write('main screen turn on', function(err) {
if (err) {
return console.log('Error on write: ', err.message)
}
console.log('message written')
})

Auto Open#

When disabling the autoOpen option you'll need to open the port on your own.

const SerialPort = require('serialport')
const port = new SerialPort('/dev/tty-usbserial1', { autoOpen: false })
port.open(function (err) {
if (err) {
return console.log('Error opening port: ', err.message)
}
// Because there's no callback to write, write errors will be emitted on the port:
port.write('main screen turn on')
})
// The open event is always emitted
port.on('open', function() {
// open logic
})

Reading Data#

Get updates of new data from the serial port as follows:

// Read data that is available but keep the stream in "paused mode"
port.on('readable', function () {
console.log('Data:', port.read())
})
// Switches the port into "flowing mode"
port.on('data', function (data) {
console.log('Data:', data)
})
// Pipe the data into another stream (like a parser or standard out)
const lineStream = port.pipe(new Readline())

You can write to the serial port by sending a string or buffer to the write method:

port.write('Hi Mom!')
port.write(Buffer.from('Hi Mom!'))

Enjoy and do cool things with this code.

Last updated on by Francis Gulotta