D1 Tape Protocol

The wire protocol of DYMO's D1 tape printers — every standalone LabelManager / LabelPoint chassis and the tape engine on the LabelWriter Duo.

Chassis families, USB topology, mode-switch, and head geometry live in Chassis and USB topology. The LabelWriter Duo pairs this tape engine with the LW raster protocol on a second USB interface (label side).

Opcode vocabulary

The complete D1 vocabulary is ESC A through ESC E plus the SYN data opcode. Anything else is unrecognised by the firmware; some unrecognised opcodes silently corrupt the parser state and brick the device until power-cycle. Don't experiment on hardware you'd mind losing.

Opcode	Bytes	Description
ESC A	1B 41	Status query.
ESC B	1B 42 N	Set Dot Tab bias offset — skip N bytes from left.
ESC C	1B 43 n	Set tape type / colour palette.
ESC D	1B 44 N	Set bytes-per-line. ESC D 0 enables skip-line mode.
ESC E	1B 45	Cut.
SYN	16 + N	Print one row (or, with ESC D 0, advance one row).

Print job structure

A complete job is a single byte stream sent to the OUT endpoint, repeated once per copy:

[per copy]
  ESC C n           — set tape type / colour palette (n = 0..12)
  ESC B dotTab      — head-axis bias offset (bytes from left)
  ESC D N           — set bytes-per-line for content (N = ceil(rasterDots / 8))
  [for each row]
    SYN row…        — one column of pixel data
  [if trailing skip: ESC D 0 + N × SYN]   — post-print tape advance
  [if autocut:       ESC E]               — cut tape (autocut chassis only)
  ESC A             — status query (ends the job)

Emitting ESC B every job (including dotTab = 0) is probably a good idea — the firmware can carry a non-zero margin across jobs, so an explicit ESC B 0 resets it.

Trailing tape advance pushes the printed region forward past the cutter blade so the cut lands on bare tape, not on print. It's emitted as bare 0x16 SYN bytes against ESC D 0: each byte advances one dot row with no payload — same physical feed as a blank padded row, at 1 byte per row instead of 1 + bytesPerLine.

On the LabelManager PnP, 16 mm of trailing advance centres the printed content between the cut and the head — 8 mm of bare tape on each side of the print. Exact figures vary by chassis (head-to-cutter distance is mechanical).

ESC A — status query

1B 41

A pure status read: no cut, no advance, no buffer flush. Conventionally emitted at the end of every job, but the firmware will accept and print the preceding stream regardless.

The printer replies with one byte on the IN endpoint:

Bit	Mask	Meaning
6	0x40	Cassette inserted
4	0x10	Cutter jammed (no-op on manual-cutter chassis)
2	0x04	General error

Bits 7, 5, 3, 1, 0 are ignore.

Example values: 0x40 idle / ready · 0x00 no cassette · 0x50 loaded + cutter jam · 0x44 loaded + general error.

D1 firmware reports cassette presence only, never type.

ESC B — Dot Tab bias offset

1B 42 N

Skips N bytes (i.e. 8 × N pins) from the left print edge before each SYN row's payload lands on the head. A Dot Tab of 3 starts the data 24 pixels in.

Useful when printing a narrower cassette on a wider head: instead of padding N zero bytes onto every raster row to centre the bitmap, set the Dot Tab once and emit only the cassette's printable payload.

Range: 0 … (headDots / 8) - 1. Values above the maximum are clamped at print time, not rejected:

Head pins	Max N
64	7
96	11
128	15

See tape width and head geometry for head-vs-cassette pin counts.

ESC C — set tape type

1B 43 nn

n selects the tape-type / colour palette (the cassette's text + substrate combination); the firmware uses it to pick the strobe profile / heat-sensitivity curve. The byte is host-declared — firmware detects cassette presence but not type, so the host has to declare what's loaded. The byte does not change the printed ink (ink is determined by the cassette itself); the matching value gives correct heat calibration and noticeably better print quality on coloured / reverse-print substrates. 0 is safe when the cartridge is unknown.

n	Combination	n	Combination
0	Black on white or clear	7	Black on fluorescent green
1	Black on blue	8	Black on fluorescent red
2	Black on red	9	White on clear
3	Black on silver	10	White on black
4	Black on yellow	11	Blue on white or clear
5	Black on gold	12	Red on white or clear
6	Black on green

Always send this before the bytes-per-line command. Sent once per copy (not per row).

ESC D — set bytes-per-line

1B 44 N

N is the number of payload bytes that will follow each SYN opcode, computed as ceil(rasterDots / 8). The full head-vs-cassette mapping is in tape width and head geometry: 4 bytes for 6 mm tape, 8 for 12/19 mm on the 64-pin head, 16 for 24 mm on the 128-pin Duo tape head.

ESC D 0 is a special case used for skip-lines: each subsequent SYN byte feeds one dot row with zero payload bytes. Re-issue ESC D N to return to printing.

ESC E — cut

1B 45

Drives the blade on motorised-cutter chassis. No-op on manual-cutter chassis (the user advances tape with the chassis lever instead).

SYN — raster row (one column)

16 b0 b1 ... b(N-1)

0x16 is the SYN opcode. The N payload bytes carry one column of pixel data, MSB-first within each byte. Bit 7 of b0 is the topmost pin; bit 0 of b(N-1) is the bottommost pin (or one of the inactive margin pins, depending on tape width).

D1 tape printers feed the tape forward by one column per row — the "row" axis in the byte stream is along the feed direction, not across the head. Landscape source bitmaps must be rotated 90° clockwise before emission.

References

• LabelWriter 400 Series Printers Technical Reference Manual and LabelWriter® 450 Series Printers Technical Reference Manual, DYMO / Sanford. The two manuals carry the same D1 specification and agree with each other — ESC A..E + SYN opcode set, Dot Tab semantics, and the tape-type table.
• labelle — Python driver for the same hardware family. Reference implementation of the D1 opcode set and the skip-lines pattern.
• dymoprint — Python predecessor of labelle (deprecated 2023).