dymon

Command line based print tool for DYMO LabelWriter Wireless. Contains protocol description to interface with DYMO LabelWriter Wireless.

Intro

2018 I bought DYMO's new wireless label printer (LabelWriter Wireless). I had the idea to print labels out of an (web)application containing data like numbers and barcodes dynamically retrieved from a database.

My starting point was the DYMO's LabelWriter SDK. Unfortunately there was little information for LabelWriter Wireless. If found LabelWriter 450 Series Printers Technical Reference Manual via Google but none for LabelWriter Wireless. I get in contact with DYMO's support and asked for a Reference Manual for LabelWriter Wireless but I got only the one for LabelWriter 450.

The Reference Manual for LabelWriter 450 Series Printers had some useful information but not exactly that what I wanted to know. Searching around the internet ended up in two interessting projects whose sourcecode contains additional informaiton:

Nevertheless I still didn't have all required information to "operatate" the LabelWriter Wireless out of my own application. So it was time for Wireshark to capture the communication between the DYMO's label creater software DYMO Label and LabelWriter Wireless... To make it short: Based on the information provided in the resouces noted above I managed it to figure out the majority of the TCP communication protocol.

Findings

For communiction with the LabelWriter Wireless TCP port 9100 is used. This makes sense, because port 9100 is reserved for PDL (page description language) data streams, used for printing to certain network printers. Communicatin is NOT encrypted.

The printer implements a kind of ESC protocol. The commands are similar as specified in LabelWriter 450 Series Printers Technical Reference Manual but not in all cases. Also there are commands, that aren't described in this document.

Each command starts with 0x1B followed by a "command selector byte" and optional parameter data. These parameter are little endian encoded.

The label itself is given by a bitmap "blob". In a preceeding header some meta information are defined. Among other things the width (number of columns) and height (number of rows) of the bitmap, the label length, print density, print quality...

The bits of the bitmap blob are mapped to label pixels row by row, column by column (Z)

It starts in upper left corner with bit 7 of the first bitmap-byte.
The next pixel (1st row, 2nd column) is followed by bit 6 ...
There is a wrap around at the end of each row ...
It ends in the lower right corner with bit 0 of the last byte.

I just testes this with a label width that is a multipel of 8. So the wrap around is at a byte boundary, and there are no unused trailing bits in the blob. Don't know what happens if this isn't considered!?

Protocol

Example for printing a 272x252 bitmap to a 25mm X 25mm label with 300x300dpi.

Open TCP connection
Get status of printer
1. 0x1B, 0x41, 1 : Send a TCP packet containing 3 bytes (2 byte command, 1 unknown byte)
2. Receive reply from printer (32 bytes, whose meaning is not known, yet!)
Send label data as ONE blob Either one big packet or multible packets with (all packets but the last) MSG_MORE flag set.
1. Set "header data" of label to be print (may be one packet with MSG_MORE)
  1. 0x1B, 0x41, 1, 0, 0, 0 : Counter, 2 byte command, 32-bit value (meaning of counter unknown)
  2. 0x1B, 0x43, 0x64 : Print-Density, 2 byte command, 1 byte value (0x64 ^= normal)
  3. 0x1B, 0x4C, 0x58, 0x02 Label-Length in 1/600 inch, 2 byte command, 16-bit value (e.g 1 inch ^= 600 ^= 0x258 ^= [0x58, 0x02])
  4. 0x1B, 0x43 : Printer quality (300x300 dpi)
  5. 0x1B, 0x4D, 0, 0, 0, 0, 0, 0, 0, 0 : Media/Paper-Type, 2 byte command, 8 byte value (8x0 ^= normal)
  6. 0x1B, 0x68 : Unknown 2 byte command
  7. 0x1B, 0x6E, 1, 0 : Label index, 2 byte command, 16-bit value (meaning of index unknown)
  8. 0x1B, 0x44, 0x01, 0x02, 0xFC, 0, 0, 0, 0x10, 0x01, 0, 0 : Bitmap spec, 2 byte command, 2 unknown bytes, 32-bit bitmap height, 32-bit bitmap width (height 252px = 0xFC ^= [0xFC, 0, 0, 0]; width 272px = 0x110 ^= [0x10, 0x01, 0, 0])
2. Send bitmap "blob" (may be next packet with MSG_MORE)
3. Send "footer data" of label (last packet of blob - MSG_MORE clear!)
  1. 0x1B, 0x47 : Short form feed, 2 byte command
  2. 0x1B, 0x41, 0 : Get status, 2 byte command, 1 unknown byte
Receive reply from printer (32 bytes, whose meaning is not known, yet!)
Send a TCP packet containing following data to output label
1. 0x1B, 0x45 : Line feed, 2 byte command
2. 0x1B, 0x51 : Line tab, 2 byte command
Close TCP connection

Label length is user for form feed. Its scale is 600dpi. In this example: 600 dots * 600 dpi = 1 inch = 25 mm.

Implementation

This command line tool for linux implements the described application. However most of the application code relates to the creation of the bitmap (text and barcode). The actual code to interface with the LabelWriter can be found in class Dymon in dymon.cpp. (Dymon is an abstact class. There is a specialization for Windows and one for Linux. Those child classes only handles the TCP network access.)

How to build

Build process is based on CMake.

Create a build directory (e.g. mkdir build)
Within the build directory execute cmake ..
Within the build directory execute make

Usage

This tool expects its input via command line argument:

1st argument: the IP of the LabelWriter in the local network
2nd argument: the labels title line
3rd/4th argument: label body lines
5th argument: EAN8 barcode value (max 7 digits. a checksum char is added automatically). This argument is expected to be a JSON object of the following format:

Example:

./dymon "192.168.178.49" "Headline is bigger" "than the following..." "...two body lines" 1234567

alacky / dymon