SerialPort
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Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The SerialPort
interface of the Web Serial API
provides access to a serial port on the host device.
Constructor
Instances of this interface may be obtained by calling methods of the Serial
interface, therefore it has no constructor of its own.
Instance properties
SerialPort.readable
Read only Experimental-
Returns a
ReadableStream
for receiving data from the device connected to the port. SerialPort.writable
Read only Experimental-
Returns a
WritableStream
for sending data to the device connected to the port.
Instance methods
SerialPort.forget()
Experimental-
Returns a
Promise
that resolves when the port closes and is forgotten. SerialPort.getInfo()
Experimental-
Returns an object containing properties of the port.
SerialPort.open()
Experimental-
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. SerialPort.setSignals()
Experimental-
Sets control signals on the port and returns a
Promise
that resolves when they are set. SerialPort.getSignals()
Experimental-
Returns a
Promise
that resolves with an object containing the current state of the port's control signals. SerialPort.close()
Experimental-
Returns a
Promise
that resolves when the port closes.
Events
connect
Experimental-
An event fired when the port has connected to the device.
disconnect
Experimental-
An event fired when the port has disconnected from the device.
Examples
Opening a port
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 */ });
Once the Promise
returned by open()
resolves the readable
and writable
attributes can be accessed to get the ReadableStream
and WritableStream
instances for receiving data from and sending data to the connected device.
Reading data from a port
The following example shows how to read data from a port. The outer loop handles non-fatal errors, creating a new reader until a fatal error is encountered and readable
becomes null
.
js
while (port.readable) {
const reader = port.readable.getReader();
try {
while (true) {
const { value, done } = await reader.read();
if (done) {
// |reader| has been canceled.
break;
}
// Do something with |value|…
}
} catch (error) {
// Handle |error|…
} finally {
reader.releaseLock();
}
}
Writing data to a port
The following example shows how to write a string to a port. A TextEncoder
converts the string to a Uint8Array
before transmission.
js
const encoder = new TextEncoder();
const writer = port.writable.getWriter();
await writer.write(encoder.encode("PING"));
writer.releaseLock();
Specifications
Specification |
---|
Web Serial API # dom-serialport |
Browser compatibility
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