Node.js package

@thermal-label/labelwriter-node provides USB and TCP transport integration and the LabelWriterPrinter class — implementing the PrinterAdapter interface from @thermal-label/contracts, built on @thermal-label/transport.

Install

pnpm add @thermal-label/labelwriter-node

---

The adapter

LabelWriterPrinter implements PrinterAdapter. Every @thermal-label/* driver exports the same surface, so application code never branches on family:

Method	Description
print(image, media?, options?)	Print one label; accepts full RGBA
createPreview(image, options?)	Render the 1bpp plane for UI previews
getStatus()	PrinterStatus — ready, media, errors, raw bytes
close()	Release the transport
family / model / device / connected	Identification
recover()	(driver extension) send error-recovery sequence

---

Discovery

import { discovery } from '@thermal-label/labelwriter-node';

const printers = await discovery.listPrinters();
// [{ device, serialNumber, transport: 'usb', connectionId: '1:2' }, ...]

// First matching USB printer
const printer = await discovery.openPrinter();

// Specific serial
const specific = await discovery.openPrinter({ serialNumber: 'AB1234' });

// Target the LabelWriter 550
const lw550 = await discovery.openPrinter({ vid: 0x0922, pid: 0x0052 });

discovery is also exported as a named singleton so the unified thermal-label-cli can pick it up automatically.

TCP printers (550 Turbo / 5XL / Wireless) are not surfaced by listPrinters() — there is no mDNS implementation. Open them explicitly by host:

const printer = await discovery.openPrinter({ host: '192.168.1.100' });
const custom = await discovery.openPrinter({ host: '10.0.0.5', port: 9200 });

---

Printing

import { discovery } from '@thermal-label/labelwriter-node';
import { MEDIA } from '@thermal-label/labelwriter-core';

const printer = await discovery.openPrinter();
try {
  await printer.print(image, MEDIA.ADDRESS_STANDARD, {
    density: 'high',
    copies: 2,
  });
} finally {
  await printer.close();
}

image is RawImageData — { width, height, data } with data as RGBA Uint8Array. Any image pipeline that outputs RGBA works — @napi-rs/canvas, sharp, node-canvas, or a pre-rendered buffer from a design tool.

Options

Option	Type	Default	Description
density	'light' | 'medium' | 'normal' | 'high'	'normal'	Print density
copies	number	1	Copies to print
compress	boolean	false	Enable RLE compression
mode	'text' | 'graphics'	'text'	Print mode hint
roll	0 | 1	undefined	Roll selector (Twin Turbo / 450 Duo)
jobId	number	auto	550-series job ID (auto-filled from Date.now())

Media

import { MEDIA, type LabelWriterMedia } from '@thermal-label/labelwriter-core';

MEDIA.ADDRESS_STANDARD; // 89×28 mm — DEFAULT_MEDIA for previews
MEDIA.ADDRESS_LARGE; // 89×36 mm
MEDIA.SHIPPING_STANDARD; // 102×59 mm
MEDIA.SHIPPING_LARGE; // 102×159 mm
MEDIA.FILE_FOLDER; // 19×87 mm
MEDIA.CONTINUOUS_56MM; // 56 mm continuous

On LabelWriter 550 / 550 Turbo / 5XL, getStatus() populates detectedMedia from the 32-byte status response. Subsequent print() calls without an explicit media argument will reuse the detection automatically. On the LabelWriter 450 series, media detection isn't available — pass media explicitly or print() throws MediaNotSpecifiedError.

---

Status

const status = await printer.getStatus();

status.ready; // printer idle and error-free
status.mediaLoaded; // tape / label roll present
status.detectedMedia; // LabelWriterMedia | undefined (550 only)
status.errors; // PrinterError[] with { code, message }
status.rawBytes; // raw status response for diagnostics

Error codes:

Code	Meaning
not_ready	Printer is busy
no_media	No labels loaded / paper out
label_too_long	Label exceeded max length
paper_jam	Paper jam detected (550)
cover_open	Cover is open (550)

---

Error recovery

After a jam / paper-out / label-too-long error, send the recovery sequence:

await printer.recover();
const status = await printer.getStatus();

recover() is a driver-specific extension on LabelWriterPrinter, not part of PrinterAdapter.

---

API summary

Export	Description
discovery	PrinterDiscovery singleton — enumerate & open
LabelWriterDiscovery	Class form, for a second instance
LabelWriterPrinter	Adapter class (directly or via discovery)