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QL720NW

Latest version: 1.0.0

This is a driver library for the Brother Label Printer QL720NW. The printer’s data sheet can be found here. This library exposes basic text and barcode print functionality. It does not implement all of the functionality offered by the printer and outlined in the data sheet. Please submit pull requests for added features.

Note The QL-720NW has been discontinued and may be hard to purchase. We have also tested this library on the Brother QL-1050 and confirmed that it supports both the QL-720NW and QL-1050 printers. Please note that the default baud rate for the QL-720NW is 9600 and the default baud rate for the QL-1050 is 115,200, so the UART will need to be configured accordingly.

You can view the library’s source code on GitHub. Click here to see information on all released versions of this library.

To use this library, add #require "QL720NW.device.lib.nut:1.0.0" to the top of your device code

Class Usage

All public methods in the QL720NW class return this, allowing you to easily chain multiple commands together:

printer
    .setOrientation(QL720NW_LANDSCAPE)
    .setFont(QL720NW_FONT_SAN_DIEGO)
    .setFontSize(QL720NW_FONT_SIZE_48)
    .write("San Diego 48")
    .print();

Constructor: QL720NW(uart[, init])

The class constructor has one required parameter: a pre-configured imp UART object. You can also supply a boolean parameter, init, but this is optional. By default init is set to true and this causes the constructor to call the initialize() method, which will run the setup commands to put the printer in ESC/P standard mode and set up the printer’s defaults.

// Configure QL-720NW Printer
uart <- hardware.uart12;
uart.configure(9600, 8, PARITY_NONE, 1, NO_CTSRTS, function() {
    server.log(uart.readstring());
});

printer <- QL720NW(uart);
// Configure QL-1050 Printer
uart <- hardware.uart12;
uart.configure(115200, 8, PARITY_NONE, 1, NO_CTSRTS, function() {
    server.log(uart.readstring());
});

printer <- QL720NW(uart);

Class Methods

initialize()

This method runs the setup commands to put the printer in ESC/P standard mode and initialize its defaults.

printer.initialize();

setOrientation(orientation)

This method sets the orientation of the printed text. It has one required parameter, orientation, into which should be passed either of the constants QL720NW_LANDSCAPE or QL720NW_PORTRAIT.

Note The value of orientation is written to UART when the method is called, and so will take effect immediately and affect everything stored in the print buffer.

// Set to landscape mode
printer.setOrientation(QL720NW_LANDSCAPE);
// Set to portrait mode
printer.setOrientation(QL720NW_PORTRAIT);

setRightMargin(column)

This method sets the printer’s right-hand margin. It has one parameter, column, which is an integer. The position of the right-hand margin is the character width times column from the left edge. See the ‘Margin Notes’ diagram, below, for more details.

Note The value of column is written to UART when the method is called, and so will take effect immediately and affect everything stored in the print buffer.

setLeftMargin(column)

This method sets the printer’s left-hand margin. It has one parameter, column, which is an integer. The position of the left-hand margin is the character width times column from the left edge. See the ‘Margin Notes’ diagram, below, for more details.

Note The value of column is written to UART when the method is called, and so will take effect immediately and affect everything stored in the print buffer.

Margin Notes

Margin Column Settings

Cases when margin settings are ignored include:

  • The left margin is to the right of the right margin.
  • The difference between the right and left margins is less than one character.
  • The print medium is continuous length tape with no page length specified and the print orientation is landscape.
// Print 'Hello' and 'world' on different lines using margin settings
printer
  .setOrientation(QL720NW_PORTRAIT);
  .setFont(QL720NW_FONT_BROUGHAM)
  .setFontSize(QL720NW_FONT_SIZE_32)
  .write("Hello world")
  .setLeftMargin(5)
  .setRightMargin(11)
  .print();

setFont(font)

This method sets the font, which is selected by passing one of constants listed in the table below into the fonts parameter. Brougham is the default font.

Font Constant
QL720NW_FONT_BROUGHAM
QL720NW_FONT_LETTER_GOTHIC_BOLD
QL720NW_FONT_BRUSSELS
QL720NW_FONT_HELSINKI
QL720NW_FONT_SAN_DIEGO

Note setFont() settings only affect text sent to the printer after the method is called. Font settings are often cleared after pageFeed() or print() are called, so it is best to set the font for each label.

// Set font to Helsinki
printer.setFont(QL720NW_FONT_HELSINKI);

setFontSize(size)

This method sets the font size in points, which is chosen by passing one of constants listed in the table below into the size parameter. The default size is 32.

Size Constant
QL720NW_FONT_SIZE_24
QL720NW_FONT_SIZE_32
QL720NW_FONT_SIZE_48

Note setFontSize() settings only effect text sent to the printer after the method is called. Font settings are often cleared after pageFeed() or print() are called, so it is best to set the font size for each label.

// Set font size to 48
printer.setFontSize(QL720NW_FONT_SIZE_48);

write(text[, options])

This method adds the text to be printed. It has one parameter, text, into which a string containing the text to be printed is passed. It also has one optional parameter, options, which takes any of the following constants: QL720NW_ITALIC, QL720NW_BOLD and QL720NW_UNDERLINE. These options can be combined by OR-ing them, as the example below shows. By default no options are set.

Note This method stores the text to be printed in a buffer. To print the buffer, you must also call print(), as the example below shows.

// Print an underlined and italicized line of text
printer.setFont(QL720NW_FONT_SAN_DIEGO)
       .setFontSize(QL720NW_FONT_SIZE_48)
       .write("Hello World", QL720NW_UNDERLINE | QL720NW_ITALIC )
       .print();

writen(text[, options])

This method adds a line of text to be printed and automatically appends the text with a New Line character. It has one parameter, text, into which a string containing the line to be printed is passed. It also has one optional parameter, options, which takes any of the following constants: QL720NW_ITALIC, QL720NW_BOLD and QL720NW_UNDERLINE. These options can be combined by OR-ing them, as the example below shows. By default no options are set.

Note This method stores the text to be printed in a buffer. To print the buffer, you must also call print() as the example below shows.

// Print an italicized line of text then an underlined line of text
printer.setFont(QL720NW_FONT_SAN_DIEGO)
       .setFontSize(QL720NW_FONT_SIZE_48)
       .writen("Hello World", QL720NW_BOLD | QL720NW_ITALIC )
       .write("I'm Alive!", QL720NW_UNDERLINE )
       .print();

newline()

This method adds a New Line character to the print buffer.

// Print two lines of text
printer.setFont(QL720NW_FONT_SAN_DIEGO)
       .setFontSize(QL720NW_FONT_SIZE_48)
       .write("Hello World")
       .newline()
       .write("I'm Alive!")
       .print();

pageFeed()

This method adds a Page Feed character to the print buffer. Please note that after printing a Page Feed, font name and size settings are often reset to defaults.

// Print two labels in one print job
printer.setFont(QL720NW_FONT_SAN_DIEGO)
       .setFontSize(QL720NW_FONT_SIZE_48)
       .write("Hello World")
       .pageFeed()
       .write("I'm Alive!")
       .print();

writeBarcode(data[, configuration])

This method defines a barcode for printing. It has one required parameter, data, which is an integer or string value and is the value to be presented as a barcode. It also has one optional parameter, configuration, which takes a table of barcode parameters.

Configuration Table

Configuration Table Key Value Data type Default Value Description
type Barcode Type Constant QL720NW_BARCODE_CODE39 Type of barcode to print. See table below
charsBelowBarcode Boolean true Whether to print data below the barcode
width Barcode Width Constant QL720NW_BARCODE_WIDTH_XS Width of barcode. See table below
height Float 0.5 Height of barcode in inches
ratio Barcode Ratio Constants QL720NW_BARCODE_RATIO_2_1 Ratio between thick and thin bars. Setting available only for type QL720NW_BARCODE_CODE39, QL720NW_BARCODE_ITF or QL720NW_BARCODE_CODABAR. See table below

Barcode Type Constants

Barcode Type Constant Data Length
QL720NW_BARCODE_CODE39 1-50 characters ("*" is not included)
QL720NW_BARCODE_ITF 1-64 characters
QL720NW_BARCODE_EAN_8_13 7 characters (EAN-8), 12 characters (EAN-13)
QL720NW_BARCODE_UPC_A 11 characters
QL720NW_BARCODE_UPC_E 6 characters
QL720NW_BARCODE_CODABAR 3-64 characters (Must begin and end with A, B, C, D)
QL720NW_BARCODE_CODE128 1-64 characters
QL720NW_BARCODE_GS1_128 1-64 characters
QL720NW_BARCODE_RSS 3-15 characters (begins with "01")
QL720NW_BARCODE_CODE93 1-64 characters
QL720NW_BARCODE_POSTNET 5 characters, 9 characters,11 characters
QL720NW_BARCODE_UPC_EXTENTION 2 characters, 5 characters

Barcode Width Constants

Barcode Width Constant
QL720NW_BARCODE_WIDTH_XXS
QL720NW_BARCODE_WIDTH_XS
QL720NW_BARCODE_WIDTH_S
QL720NW_BARCODE_WIDTH_M
QL720NW_BARCODE_WIDTH_L

Barcode Ratio Constants

Barcode Ratio Constant
QL720NW_BARCODE_RATIO_2_1
QL720NW_BARCODE_RATIO_25_1
QL720NW_BARCODE_RATIO_3_1

Note This method stores the barcode to be printed in a buffer. To print the barcode, you must also call print(), as the example below shows.

// Print the device's MAC address as a barcode
barcodeConfig <- {"type" : QL720NW_BARCODE_CODE39,
                  "charsBelowBarcode" : true,
                  "width" : QL720NW_BARCODE_WIDTH_M,
                  "height" : 1,
                  "ratio" : QL720NW_BARCODE_RATIO_3_1 }

local i = imp.net.info();
local a = i.interface[("active" in i ? i.active : 0)];
printer.writeBarcode(a.macaddress, barcodeConfig)
       .print();

write2dBarcode(data, type[, configuration])

This method creates a 2D barcode. It has two required parameters. The first, data, takes an integer or string and which is the data to be printed as a barcode. The second, type, specifies the type of barcode to be printed. The method also has one optional parameter, configuration, which takes a table of configuration parameters. Which configuration parameters are available depends on which type of 2D barcode you select — both sets are listed in the tables below.

The supported 2D types are QR, selected by passing the constant QL720NW_BARCODE_2D_QR into type, and Data Matrix, which selected by passing in the constant QL720NW_BARCODE_2D_DATAMATRIX.

QR Configuration Table

Configuration Table Key Value Data type Default Value Description
cell_size Integer 3 Specifies the dot size per cell side. Supported values are 3, 4, 5, 6, 8 and 10
symbol_type Symbol Type Constant QL720NW_BARCODE_2D_QR_SYMBOL_MODEL_2 Symbol type to be used. See table below
structured_append_partitioned Boolean false Whether the structured append is partitioned
code_number Integer 0 Indicates the number of the symbol in a partitioned QR Code. Must set a number between 1-16 if structured_append_partitioned is set to true
num_partitions Integer 0 Indicates the total number of symbols in a partitioned QR Code. Must set a number between 2-16 if structured_append_partitioned is set to true
parity_data hexadecimal 0 Value in bytes of exclusively OR-ing all the print data (print data before partition)
error_correction Error Correction Constant QL720NW_BARCODE_2D_QR_ERROR_CORRECTION_STANDARD See table below
data_input_method Data Input Method Constant QL720NW_BARCODE_2D_QR_DATA_INPUT_AUTO Auto: QL720NW_BARCODE_2D_QR_DATA_INPUT_AUTO,
Manual: QL720NW_BARCODE_2D_QR_DATA_INPUT_MANUAL

QR Symbol Type Constants

Symbol Type Constant
QL720NW_BARCODE_2D_QR_SYMBOL_MODEL_1
QL720NW_BARCODE_2D_QR_SYMBOL_MODEL_2
QL720NW_BARCODE_2D_QR_SYMBOL_MICRO_QR

QR Error Correction Constants

Error Correction Constant Level
QL720NW_BARCODE_2D_QR_ERROR_CORRECTION_HIGH_DENSITY High-density level: L 7%
QL720NW_BARCODE_2D_QR_ERROR_CORRECTION_STANDARD Standard level: M 15%
QL720NW_BARCODE_2D_QR_ERROR_CORRECTION_HIGH_RELIABILITY High-reliability level: Q 25%
QL720NW_BARCODE_2D_QR_ERROR_CORRECTION_ULTRA_HIGH_RELIABILITY Ultra-high-reliability level: H 30%

Data Matrix Configuration Table

Configuration Table Key Value Data Type Default Value Description
cell_size integer 3 Specifies the dot size per cell side. Supported values are 3, 4, 5, 6, 8 and 10
symbol_type Symbol Type Constant QL720NW_BARCODE_2D_DM_SYMBOL_SQUARE Symbol type to be used. Square: QL720NW_BARCODE_2D_DM_SYMBOL_SQUARE, Rectangular: QL720NW_BARCODE_2D_DM_SYMBOL_RECTANGLE
vertical_size integer 0 Specifies the vertical number of cells. Supported values for square type are 0 (Auto), 10, 12, 14, 16, 18, 20, 22, 24, 26, 32, 36, 40, 44, 48, 52, 64, 72, 80, 88, 96, 104, 120, 132 and 144. Supported values for rectangular type are 0 (Auto), 8, 12 and 16
horizontal_size integer 0 Specifies the horizontal number of cells. If square type is selected, horizontal_size will be set to match the vertical size. The horizontal_size is only supported in conjunction with specific vertical_size values. See table below for supported rectangular horizontal cell sizes

Data Matrix Rectangular Horizontal Size Values

Horizontal Cell Size Data Type Supported Vertical Cell Size
0 integer Auto
18 integer 8 cells
32 integer 8 cells
26 integer 12 cells
36 integer 12 cells or 16 cells
48 integer 16 cells

Note This method stores the barcode to be printed in a buffer. To print the barcode, you must also call print(), as the example below shows.

qrSettings <- { "cell_size": 5 };
dataMatrixSettings <- { "cell_size" : 8 };

// Write QR barcode
local i = imp.net.info();
local a = i.interface[("active" in i ? i.active : 0)];
printer.write2dBarcode(a.macaddress, QL720NW_BARCODE_2D_QR, qrSettings);

// Write dataMatrix barcode
printer.write2dBarcode(mac, QL720NW_BARCODE_2D_DATAMATRIX, dataMatrixSettings);

// Print barcodes
printer.print();

print()

This method outputs the contents of the print buffer as set by the write(), writen(), writeBarcode() and/or write2dBarcode() methods.

// Print a line of text
printer.write("Hello World")
       .print();

Known Issues

  • The QL-720NW appears to drop UART commands while printing. The workaround is add a pause after calling print(). The QL-1050 does not have this issue.
  • The printer state may become inconsistant when resetting font and font size between print jobs. The workaround is to always set font and font size for each label printed.

Release History

The Electric Imp Dev Center documents the latest version of the library. For past versions, please see the Electric Imp public GitHub repos listed below.

Version Source Code Notes
1.0.0 GitHub Initial release

License

The QL720NW class is licensed under the MIT License.