Class: SerialTransport

Node.js serial-port transport.

Covers three physical pipes that all look the same to userspace:

• Bluetooth SPP via /dev/rfcomm0 (Linux, after bluetoothctl pair + rfcomm bind) or COM<n> (Windows, auto-assigned after pairing). macOS dropped classic Bluetooth SPP — no serial route there.
• USB-to-serial adapters via /dev/ttyUSB0, /dev/ttyACM0, COM<n>.
• Native UARTs on embedded boards.

Baud rate is forwarded to the OS driver. For RFCOMM it is ignored by the underlying link (flow control is on the Bluetooth layer), but the serialport API requires a value — default 9600.

Buffering pattern matches TcpTransport: incoming data events push chunks into a Buffer[], and read(n) resolves once enough bytes are queued.

Implements

• Transport

Accessors

connected

Get Signature

get connected(): boolean;

Whether the transport is currently connected.

Returns

boolean

Implementation of

Transport.connected

Methods

close()

close(): Promise<void>;

Close the connection.

Always safe to call multiple times. Always await the result.

Returns

Promise<void>

Implementation of

Transport.close

---

read()

read(length: number, timeout?: number): Promise<Uint8Array>;

Read bytes from the printer.

Buffers until length bytes are available or the timeout fires.

BLE implementations: there is no "read N bytes" primitive in BLE. Implementations must buffer incoming GATT notifications internally and satisfy read() calls from that buffer. Document this in your transport class — every BLE implementation must handle buffering consistently so drivers get the same pull-based API on every transport.

Parameters

Parameter	Type
length	number
timeout?	number

Returns

Promise<Uint8Array>

Throws

TransportTimeoutError on timeout.

Throws

TransportClosedError if the transport is closed mid-read.

Implementation of

Transport.read

---

write()

write(data: Uint8Array): Promise<void>;

Send bytes to the printer.

Parameters

Parameter	Type
data	Uint8Array

Returns

Promise<void>

Implementation of

Transport.write

---

open()

static open(path: string, baudRate?: number): Promise<SerialTransport>;

Open a serial port by path.

Parameters

Parameter	Type	Default value	Description
path	string	undefined	OS-specific device path (e.g. /dev/rfcomm0, /dev/ttyUSB0, COM3).
baudRate	number	DEFAULT_BAUD_RATE	Serial baud rate. Default 9600. Ignored for Bluetooth SPP but required by the serialport API.

Returns

Promise<SerialTransport>