SerialPort: open() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

Note: This feature is available in Dedicated Web Workers.

The open() method of the SerialPort interface returns a Promise that resolves when the port is opened. By default the port is opened with 8 data bits, 1 stop bit and no parity checking. The baudRate parameter is required.

Syntax

js
open(options)

Parameters

options

An object with any of the following values:

baudRate

A positive, non-zero value indicating the baud rate at which serial communication should be established.

bufferSize Optional

An unsigned long integer indicating the size of the read and write buffers that are to be established. If not passed, defaults to 255.

dataBits Optional

An integer value of 7 or 8 indicating the number of data bits per frame. If not passed, defaults to 8.

flowControl Optional

The flow control type, either "none" or "hardware". The default value is "none".

parity Optional

The parity mode, either "none", "even", or "odd". The default value is "none".

stopBits Optional

An integer value of 1 or 2 indicating the number of stop bits at the end of the frame. If not passed, defaults to 1.

Return value

A Promise.

Exceptions

InvalidStateError DOMException

Returned if the port is already open.

NetworkError DOMException

Returned if the attempt to open the port failed.

Examples

Before communicating on a serial port it must be opened. Opening the port allows the site to specify the necessary parameters that control how data is transmitted and received. Developers should check the documentation for the device they are connecting to for the appropriate parameters.

js
await port.open({ baudRate: 9600 /* pick your baud rate */ });

Specifications

Specification
Web Serial API
# dom-serialport-open

Browser compatibility

BCD tables only load in the browser