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.

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.

A Promise.

InvalidStateError DOMException

Returned if the port is already open.

NetworkError DOMException

Returned if the attempt to open the port failed.

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.

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