PT Raster Protocol

The wire protocol of Brother's PC-connectable P-touch tape printers — PT-E550W, PT-P750W, PT-P900, PT-P900W, PT-P950NW, and PT-P910BT. All six speak the same raster command set; the family splits into a 128-pin head tier (PT-E550W, PT-P750W) and a 560-pin head tier (the P900 / P910BT models).

The closely related Brother QL series (DK die-cut and continuous roll) uses the same opcode dispatcher with different geometry, feed margin, and two-colour rules — see QL raster protocol.

USB topology

Single configuration, Printer-class interface (bInterfaceClass 0x07) with one bulk OUT (print data) and one bulk IN (status responses). Vendor ID is 0x04F9 (Brother Industries, Ltd.); per-model product IDs are listed on Hardware.

Configuration 1
  Interface 0 — Printer class (bInterfaceClass 0x07)
    Bulk OUT  (print data)
    Bulk IN   (32-byte status reply)

PT-P910BT is a Bluetooth-primary chassis and exposes the same byte stream over Bluetooth Serial Port Profile. PT-P750W, PT-P900W, PT-P950NW, and PT-E550W additionally accept the byte stream over raw TCP on port 9100. The wire format is identical across transports.

Opcode vocabulary

Opcode	Bytes	Description
NULL	00	Invalidate byte — flushes any in-progress command.
ESC @	1B 40	Reset mode settings; cancel any in-flight print.
ESC i !	1B 69 21 n	Enable or disable automatic status notifications.
ESC i A	1B 69 41 n	Cut every n-th label in a multi-page job.
ESC i a	1B 69 61 n	Switch command mode (raster, ESC/P, P-touch Template).
ESC i d	1B 69 64 n1 n2	Specify feed margin in dots (little-endian 16-bit).
ESC i K	1B 69 4B flags	Advanced mode flags (half-cut, chain print, high-res).
ESC i M	1B 69 4D flags	Various mode flags (auto-cut, mirror print).
ESC i S	1B 69 53	Request 32-byte status reply on the IN endpoint.
ESC i z	1B 69 7A + 10	Declare media type, width, length, row count, page index.
FF	0C	Print page; more pages follow.
G	67 n1 n2 d…	Transfer one raster line; n1+n2*256 payload bytes follow.
M	4D n	Select uncompressed (0) or TIFF PackBits (2) raster mode.
SUB	1A	Print page; last page of the job (feeds the tape out).
Z	5A	One blank raster line (PackBits-compressed jobs only).

Print job structure

NULL × 200           — invalidate (560-pin family; third-party drivers report 100 for the 128-pin family — treat 200 as a safe over-count)
ESC @                — initialize
ESC i a 01           — switch to raster mode
[per page]
  ESC i S            — status information request (32-byte reply on IN)
  ESC i z …          — print information (media type, width, length, row count, page index)
  ESC i M flags      — various mode (auto-cut, mirror)
  ESC i A 01         — cut each 1 label
  ESC i K flags      — advanced mode (half-cut, no chain, high-res)
  ESC i d n1 n2      — feed margin in dots
  [M 02]             — opt-in TIFF PackBits compression
  [for each row]
    G n1 n2 d…       — raster graphics transfer
    or Z             — single blank row (compressed jobs only)
  FF  | SUB          — FF between pages, SUB on the last page of the job

A complete job is a single byte stream sent to the OUT endpoint. Send the invalidate prologue and ESC @ once per connection-level reset, then one block per page. The terminating opcode on the last page is SUB (0x1A); all earlier pages end with FF (0x0C).

Compressed and uncompressed rows must not be mixed within a single page — M 02 is sticky for the rest of the job and applies to every subsequent G payload until the next ESC @. In uncompressed mode, each G row carries exactly headDots / 8 bytes — 70 on the 560-pin head (manual p. 20), 16 on the 128-pin head. In compressed mode, G's n1/n2 bytes carry the post-compression payload length and the decoded line is always headDots / 8 bytes wide. Per p. 38, if a row's compressed form would exceed 70 bytes the firmware accepts a 71-byte literal-only encoding (1 header byte + 70 raw bytes); encoders that can't guarantee a shrink should fall back to uncompressed for that row.

The 560-pin family runs at 360 × 360 DPI by default and 360 × 720 DPI when high-resolution mode is requested via ESC i K bit 6 (PT-P900 / P900W / P950NW only; PT-P910BT has no high-res mode). The 128-pin family runs at 180 × 180 DPI / 180 × 360 DPI per third-party drivers; the manual edition covering that family is not on hand to confirm. When high-resolution mode is on, each raster line is transmitted twice and the feed margin is doubled — both are required to keep the expanded image at the right physical scale, since the firmware advances the tape half as far per row at high resolution. High-res on the 560-pin family also requires ESC i z n2 to be 0x09 for laminated tape (manual p. 33); HSe and Fle don't support high-res.

Tape geometry is fixed per cassette width. Each G row covers the full head width; the printable portion of the tape sits inside a fixed left/right margin window that depends on cassette width and head family. On a 560-pin head, 24 mm TZe gives 320 print-area pins between a 112-pin left margin and a 128-pin right margin; the same cassette on a 128-pin head fits 128 print-area pins edge-to-edge.

TZe tape spans 3.5 / 6 / 9 / 12 / 18 / 24 / 36 mm widths (manual p. 13). HSe heat-shrink tubing on the 560-pin family comes in 2:1 ratios at 5.8 / 8.8 / 11.7 / 17.7 / 23.6 mm and 3:1 ratios at 5.2 / 9.0 / 11.2 / 21.0 / 31.0 mm (manual p. 14). PT-P910BT is TZe-only — every HSe row in the 560-pin manual's compatibility column reads "not supported" for PT-P910BT. PT-E550W is reported by third-party drivers to accept a subset of HSe widths; the manual edition covering that family is not on hand to confirm.

NULL — invalidate

00

A single zero byte is skipped by the parser. Long runs of NULL flush any partial command from the print buffer back to the receiving state, which is why every job begins with a fixed-size run of zero bytes before the first real opcode.

The 560-pin manual specifies a 200-byte invalidate run before ESC @. The 128-pin manual edition (covering PT-E550W / PT-P750W) is not in hand to confirm a different count; third-party drivers report 100 bytes for the 128-pin chassis. Sending 200 on either head family is safe as an over-count.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, pp. 5, 22.

ESC @ — initialize

1B 40

Resets all mode settings and discards anything still in the print buffer. Also used to cancel an in-flight print. Emitted once at the top of every job, immediately after the invalidate run.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 23.

ESC i ! — set automatic status notification mode

1B 69 21 n

n = 0 notifies (the printer pushes phase-change and error status frames during printing); n = 1 silences automatic notifications. Default is 1. The setting persists until power-off. On PT-P910BT, automatic notification is the only way to receive status during a print — the chassis does not enable bidirectional communication automatically when PI_RECOVER is set.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 41.

ESC i A — set "cut each N labels"

1B 69 41 n

When auto-cut is enabled (via ESC i M bit 6), the cutter fires every n-th label in the page sequence. Range 1..255; default 1 (cut every label). n = 0 disables cutting entirely for the remainder of the job.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 37.

ESC i a — switch dynamic command mode

1B 69 61 n

Selects the printer's command-language mode. The printer holds the selected mode until power-off.

n	Mode
0	ESC/P (default on PT-P900 / P900W / P950NW)
1	Raster
3	P-touch Template

Always send 01 (raster) before raster data. On PT-P910BT the default is already raster; sending it again is harmless.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 32.

ESC i d — specify margin amount

1B 69 64 n1 n2

Sets the leading/trailing feed margin in dots, as a little-endian 16-bit value: margin = n1 + n2 * 256. Range per the manual is 14..1800 dots at 360 × 360 DPI (roughly 1 mm to 127 mm) and 28..3600 dots at 360 × 720 DPI. Below the minimum, the firmware clamps to a hardware-imposed floor driven by the cutter-to-head distance — emitted output never feeds less than ~27 mm regardless of the requested margin.

In high-resolution mode the requested margin must be doubled to keep the resulting tape margin at the same physical length, because the feed-axis step is halved.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 37.

ESC i K — advanced mode settings

1B 69 4B flags

One flag byte:

Bit	Mask	Function
0	0x01	Draft printing (PT-P900 / P900W / P950NW; must be 0 on PT-P910BT).
2	0x04	Half-cut on.
3	0x08	No chain printing — feed and cut after the last label.
4	0x10	Special tape (no cutting).
6	0x40	High-resolution printing.
7	0x80	No buffer clearing between labels.

Bit 6 toggles the high-resolution mode described in Print job structure: each raster line is sent twice and the feed margin is doubled. PT-P910BT does not support high-res or draft and must keep bits 0 and 6 clear. Bit 7 is "not used" on PT-P910BT per the manual. Bits 1 and 5 are reserved.

Note that the QL raster dialect uses bit 4 for high resolution; PT uses bit 6 for the same feature.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 36.

ESC i M — various mode settings

1B 69 4D flags

One flag byte:

Bit	Mask	Function
6	0x40	Auto-cut.
7	0x80	Mirror printing.

Bits 0–5 are reserved or unused.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 35.

ESC i S — status information request

1B 69 53

The printer replies with a fixed 32-byte frame on the IN endpoint. Bytes 0–3 are constant (80 20 'B' '0'), useful as a sync marker against any trailing USB noise:

Offset	Field	Notes
0	Print-head mark	0x80.
1	Size	0x20 (32).
2	Brother code	'B' (0x42).
3	Series code	'0' (0x30).
4	Model code	'q' P900, 'o' P900W, 'p' P950NW, 'x' P910BT.
5	Country code	'0' (0x30).
6	Battery level	560-pin AC models: 0x00 full / 0x01 half / 0x02 low / 0x03 charge needed / 0x04 AC adapter / 0xFF unknown. PT-P910BT uses a separate table with bit 4 set when the AC adapter is connected (0x20–0x24 on battery, 0x30–0x37 on AC).
7	Extended error	0x10 Fle tape end, 0x1D high-res/draft printing error, 0x1E adapter pull/insert error, 0x21 incompatible media error.
8	Error information 1	Bitmask — see table below.
9	Error information 2	Bitmask — see table below.
10	Media width (mm)	0x04 3.5 mm … 0x24 36 mm. 0x00 if no tape.
11	Media type	0x01 laminated, 0x03 non-laminated, 0x04 fabric, 0x11 HSe 2:1, 0x13 Fle, 0x14 flexible ID, 0x15 satin, 0x17 HSe 3:1, 0xFF incompatible.
12	Number of colours	Fixed 0x00.
15	Mode	Last ESC i M value (or 0x00 if never set).
17	Media length (mm)	Always 0x00 for TZe/HSe.
18	Status type	0x00 reply, 0x01 print done, 0x02 error, 0x05 notification, 0x06 phase change.
19	Phase type	0x00 editing / 0x01 printing.
20–21	Phase number	Big-endian.
22	Notification number	Cover open / closed, cooling start / finish.
24	Tape colour ID	Cassette tape colour (see manual table 8).
25	Text colour ID	Cassette ink colour (see manual table 9).

Error information 1 (byte 8):

Bit	Mask	Meaning
0	0x01	No media.
1	0x02	End of media (not reported on PT-P910BT).
2	0x04	Cutter jam.
3	0x08	Weak batteries.
6	0x40	High-voltage adapter (not on PT-P910BT).

Error information 2 (byte 9):

Bit	Mask	Meaning
0	0x01	Replace media / wrong media.
1	0x02	Expansion buffer full (not on PT-P910BT).
2	0x04	Communication error.
3	0x08	Communication buffer full.
4	0x10	Cover open (not on PT-P910BT).
5	0x20	Overheating error.
6	0x40	Black-marking not detected (not on PT-P910BT).
7	0x80	System error.

A status request is conventionally emitted once per page, before the print-information command. The 32-byte reply must be drained from the IN endpoint before the next request, otherwise the firmware will queue the next reply behind it. Do not send ESC i S while a page is actively printing — error and phase-change frames are pushed automatically and an extra request mid-print interferes with that stream.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, pp. 23–31.

ESC i z — print information

1B 69 7A n1 n2 n3 n4 n5 n6 n7 n8 n9 n10

Declares the print job's media and dimensions. 13 bytes total.

Param	Field
n1	Valid-flag bitmask. 0x02 media type, 0x04 media width, 0x08 media length, 0x40 priority quality (unused), 0x80 recovery / bidirectional.
n2	Media type: 0x00 lam/non-lam, 0x11 HSe 2:1, 0x17 HSe 3:1, 0x13 Fle, 0xFF incompatible. 0x09 is required when printing high-res on laminated tape.
n3	Media width (mm).
n4	Media length (mm). 0x00 for TZe and HSe regardless of length; 0x2D (45 mm) for FLe 21 × 45 mm.
n5..n8	Raster row count, little-endian 32-bit: n5 + n6*256 + n7*65536 + n8*16777216.
n9	Page index. 0 first page, 1 middle page, 2 last page. Single-page jobs use 2.
n10	Fixed 0x00.

The valid-flag byte must claim every field the printer is supposed to validate. When all three of PI_KIND, PI_WIDTH, and PI_LENGTH are set and the loaded cassette doesn't match, the printer raises "Replace media" via error info 2 bit 0.

Setting bit 7 (PI_RECOVER) enables printer recovery and, on the 560-pin chassis, also turns on bidirectional communication so status frames arrive during printing. PT-P910BT does not enable bidirectional communication from this bit; use ESC i ! 00 instead.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, pp. 33–34.

FF — print command

0C

Marks the end of one page in a multi-page job. The next page's control block follows immediately.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 40.

G — raster graphics transfer

67 n1 n2 d1 … dk

One raster line. k = n1 + n2 * 256 bytes follow, expanded across the print head from the left-margin offset. If the expanded data falls short of the head width, the firmware zero-fills the remainder; overflow is truncated.

In uncompressed mode (the post-M 00 default), k is fixed at headDots / 8 — 70 on the 560-pin head per p. 40 and p. 20. The 128-pin head is encoder-hardcoded to 16 bytes; the manual edition covering that family is not on hand to confirm. In TIFF PackBits mode (after M 02), k is the post-compression length and the decoded line is still headDots / 8 bytes wide.

Note: PDF p. 40 reads "Hexadecimal: 47" in the per-command panel — that's a typo for the ASCII 'G' codepoint. The print-command list on p. 22 and every observed wire capture put the opcode at 0x67 (ASCII 'g') — 0x67 is the on-the-wire value.

Each raster row covers the full head width; content is placed at the cassette's left-margin pin count, with unused dots zeroed. Cassette left/right margins per width are in Print job structure.

When high-resolution mode is on (see ESC i K bit 6), each G payload must be transmitted twice in succession. The 560-pin manual doesn't spell this out; the rule is documented in nbuchwitz/ptouch.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 40.

M — select compression mode

4D n

n = 0 selects uncompressed transfer; n = 2 selects TIFF PackBits. n = 1 is reserved and unused. The mode is sticky and applies to every subsequent G and Z opcode until the next ESC @. PackBits is standard TIFF run-length encoding (see References); each encoded run is a signed header byte followed by data:

Header byte (signed)	Meaning
0..127	Literal — the next header + 1 bytes are verbatim.
-127..-1	Repeat — the next byte repeats 1 - header times.
-128	No-op (unused by typical encoders).

Tech Ref worked example: ED 00 encodes a 20-byte run of 0x00 (header 0xED is signed -19, so the next byte repeats 1 - (-19) = 20 times); FF 22 encodes two 0x22 bytes; 05 23 BA BF A2 22 2B encodes six literal bytes (header + 1 = 6).

Each encoded line still decodes to headDots / 8 bytes (70 on the 560-pin head); trailing zero bytes in the margin are not optional in the decoded form.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, pp. 38–39.

SUB — print command with feeding

1A

Marks the end of the last page in the job. Feeds the printed tape forward past the cutter and (when auto-cut is enabled) fires the blade. Every job must end with SUB; ending with FF leaves the last page sitting in the print buffer until the next job arrives.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 40.

Z — zero raster graphics

5A

One blank raster line. Only valid in TIFF PackBits mode — it substitutes for a fully zeroed G payload at one byte instead of the 3 + headDots/8 bytes a literal G row would cost. Uncompressed jobs must use a full G row with a zero payload instead.

Raster Command Reference — PT-P900/P900W/P950NW/P910BT, p. 40.

References

• Raster Command Reference — PT-P900/P900W/P950NW/P910BT, Version 1.02, Brother Industries, Ltd. (2020). Authoritative byte-level reference for the 560-pin family; cited inline by page. Not redistributed. The same opcode set is used by the 128-pin chassis (PT-E550W, PT-P750W); pin counts and per-tape geometry for that family are sourced from the equivalent PT-E550W / P750W / P710BT Raster Command Reference and from cross-checks against active open-source drivers.
• TIFF 6.0 Specification, Aldus Corporation (1992), § 9 "PackBits compression". The compression scheme M 02 selects. Accessible mirror: libtiff TIFF 6.0 spec PDF.
• nbuchwitz/ptouch — active LGPL-2.1 Python driver; primary cross-reference for the 128-pin head pin counts, the high-resolution line-duplication rule, and the PT-E550W "compression required for auto-cut" firmware quirk.
• hannesweisbach/ptouch-print — older C driver; secondary cross-reference, especially for the PT-P750W PLite-vs-printer USB-PID handling on first connect.