Chassis and USB topology

How D1 devices present on a USB bus: which chassis exist, what interfaces and endpoints they enumerate, the Linux-only mode-switch dance, head pin counts per cassette tier, and the WebUSB claim sequence.

The wire protocol itself lives in D1 tape protocol.

Chassis tiers

D1 chassis come in three mechanical width tiers; each accepts every smaller cassette as well.

Tier	Sizes accepted (mm)	Example chassis
12 mm	6 / 9 / 12	LM PnP, LM PC, LabelPoint 350, MobileLabeler
19 mm	+ 19	LM 420P, LM Wireless PnP, LabelWriter Duo (96-dot)
24 mm	+ 24	LabelWriter 450 Duo, LabelWriter Duo (128-dot)

All D1 devices share Vendor ID 0x0922 (DYMO-CoStar Corp.).

There are two USB topologies that carry D1: standalone LabelManager chassis, and the LabelWriter Duo (composite label-plus-tape device). Both share Vendor ID 0x0922.

Standalone LabelManager

Composite USB device with three interfaces. Per-model PIDs are listed in Mode-switch.

Configuration 1
  Interface 0 — Printer class (bInterfaceClass 0x07)
    Endpoint 0x05  OUT   Bulk    (print data)
    Endpoint 0x85  IN    Bulk    (1-byte status response)
  Interface 1 — Mass Storage (vestigial; firmware-update mode)
  Interface 2 — HID (bInterfaceClass 0x03)
    Endpoint 0x01  OUT   Interrupt
    Endpoint 0x81  IN    Interrupt

The same byte stream prints correctly on either the Printer-class OUT endpoint or the HID OUT endpoint. The Printer-class interface is the conventional choice on Linux (no kernel driver bound); HID is a valid alternative transport. Both endpoints carry wMaxPacketSize = 64.

LabelWriter Duo

The Duo is electrically a LabelWriter and a LabelManager sharing one chassis. Single USB device, single vid/pid, with two printer-class interfaces — the label side and the tape side enumerate side by side and are claimed independently.

Model	PID	Tape head
LabelWriter 450 Duo	0x0023	128
LabelWriter Duo (96-dot)	0x0017	96
LabelWriter Duo (128-dot)	0x001d	128

Configuration 1
  Interface 0 — Printer class (lw-raster label engine, 672-dot head)
    Bulk OUT / Bulk IN
  Interface 1 — Printer class (d1-tape engine, 128-dot head; 96-dot on LW_DUO_96)
    Bulk OUT / Bulk IN

The tape side speaks D1 identically to a standalone LabelManager — same ESC A..E + SYN vocabulary, same 1-byte status reply, same wMaxPacketSize = 64. Only the head pin count and the interface number change. The label side speaks lw-raster, a different protocol documented separately.

Mode-switch is not required for the Duo — it presents as the composite printer-class device from boot.

Mode-switch (Linux only)

Several models present as USB Mass Storage on first connect (the "PLite" / setup partition that ships the Windows installer). To switch to the printer interface:

1. The host sends a 3-byte vendor-specific message: 1B 5A 01 (ESC Z 01).
2. The device re-enumerates under its printer-class PID.

Model	Mass-storage PID	Printer PID
LabelManager PnP	0x1001	0x1002
LabelManager 280	0x1005	0x1006

On Linux, this is handled by usb_modeswitch plus a udev rule. macOS and Windows automatically switch to printer mode when the OS driver loads, so no host-side action is needed.

Tape width and head geometry

Each cassette has a fixed maximum number of printable dots; the host sends ESC D N bytes per row, where N = ceil(maxDots / 8):

Tape width	Max dots	ESC D N
6 mm	32	4
9 mm	48	6
12 mm	64	8
19 mm	96	12
24 mm	128	16

A head can't address more dots than its pin count. On a 64-pin head, 19 mm and 24 mm cassettes print on a centred 64-dot strip (ESC D 8); the wider tape lives outside the print region. The Duo's 96-dot head reaches the full 19 mm width; its 128-dot head adds 24 mm.

ESC B (Dot Tab) centres a narrower cassette on a wider head — the value is the left-side excess in bytes:

Tape width	64-dot head	96-dot head	128-dot head
6 mm	2	4	6
9 mm	1	3	5
12 mm	0	2	4
19 mm	—	0	2
24 mm	—	—	0

So a 12 mm cassette on the 128-dot Duo head wants ESC D 8 plus ESC B 4, landing 32 pixels in from the left edge of the head.

WebUSB

WebUSB is supported as a transport for D1. The interface to claim depends on the chassis — D1 lives on Interface 0 on a standalone LabelManager and on Interface 1 on a LabelWriter Duo.

Standalone LabelManager:

device.open()
  → device.selectConfiguration(1)
  → device.claimInterface(0)        // Printer class
  → device.transferOut(5, chunk)    // 64-byte chunks → EP 5 OUT
  → device.transferIn(5, 1)         // 1-byte status reply ← EP 5 IN

LabelWriter Duo (tape side):

device.open()
  → device.selectConfiguration(1)
  → device.claimInterface(1)        // tape engine
  → device.transferOut(<ep>, chunk) // 64-byte chunks → IF 1 bulk OUT
  → device.transferIn(<ep>, 1)      // 1-byte status reply ← IF 1 bulk IN

The label side of the same Duo chassis lives on Interface 0 and speaks lw-raster; only the tape side is D1. Each interface is claimed independently — a host that drives both engines holds two claims on the same USBDevice.

WebUSB requires a secure context (https:// or localhost). Mode-switch is not possible from the browser; standalone LabelManager chassis stuck in mass-storage mode require desktop-side setup first. The Duo does not need mode-switch.

WebHID against the LabelManager's IF 2 (EP 1 OUT / EP 0x81 IN) prints the same byte stream — the protocol does not distinguish the two transports.