Usage

Last Reviewed:2017-06-10

Define your printer

USB printer

Before creating your Python ESC/POS printer instance, consult the system to obtain the printer parameters. This is done with the ‘lsusb’ command.

Run the command and look for the “Vendor ID” and “Product ID” and write down the values. These values are displayed just before the name of the device with the following format:

xxxx:xxxx

Example:

# lsusb
Bus 002 Device 001: ID 04b8:0202 Epson ...

Write down the the values in question, then issue the following command so you can get the “Interface” number and “End Point”

# lsusb -vvv -d xxxx:xxxx | grep iInterface
    iInterface              0
# lsusb -vvv -d xxxx:xxxx | grep bEndpointAddress | grep OUT
      bEndpointAddress     0x01  EP 1 OUT

The first command will yield the “Interface” number that must be handy to have and the second yields the “Output Endpoint” address.

USB Printer initialization

p = printer.Usb(0x04b8,0x0202)

By default the “Interface” number is “0” and the “Output Endpoint” address is “0x01”. If you have other values then you can define them on your instance. So, assuming that we have another printer, CT-S2000, manufactured by Citizen (with “Vendor ID” of 2730 and “Product ID” of 0fff) where in_ep is on 0x81 and out_ep=0x02, then the printer definition should look like:

Generic USB Printer initialization

p = printer.Usb(0x2730, 0x0fff, 0, 0x81, 0x02)

Network printer

You only need the IP of your printer, either because it is getting its IP by DHCP or you set it manually.

Network Printer initialization

p = printer.Network("192.168.1.99")

Serial printer

Most of the default values set by the DIP switches for the serial printers, have been set as default on the serial printer class, so the only thing you need to know is which serial port the printer is connected to.

Serial printer initialization

p = printer.Serial("/dev/tty0")

# on a Windows OS serial devices are typically accessible as COM
p = printer.Serial("COM1")

Other printers

Some printers under /dev can’t be used or initialized with any of the methods described above. Usually, those are printers used by printcap, however, if you know the device name, you could try to initialize by passing the device node name.

p = printer.File("/dev/usb/lp1")

The default is “/dev/usb/lp0”, so if the printer is located on that node, then you don’t necessary need to pass the node name.

Define your instance

The following example demonstrates how to initialize the Epson TM-TI88IV on a USB interface.

from escpos import *
""" Seiko Epson Corp. Receipt Printer M129 Definitions (EPSON TM-T88IV) """
p = printer.Usb(0x04b8,0x0202)
# Print text
p.text("Hello World\n")
# Print image
p.image("logo.gif")
# Print QR Code
p.qr("You can readme from your smartphone")
# Print barcode
p.barcode('1324354657687','EAN13',64,2,'','')
# Cut paper
p.cut()

Standard python constraints on libraries apply. This means especially that you should not name the script in which you implement these lines should not be named escpos as this would collide with the name of the library.

Configuration File

You can create a configuration file for python-escpos. This will allow you to use the CLI, and skip some setup when using the library programmatically.

The default configuration file is named config.yaml and uses the YAML format. For windows it is probably at:

%appdata%/python-escpos/config.yaml

And for linux:

$HOME/.config/python-escpos/config.yaml

If you aren’t sure, run:

from escpos import config
c = config.Config()
c.load()

If it can’t find the configuration file in the default location, it will tell you where it’s looking. You can always pass a path, or a list of paths, to the load() method.

To load the configured printer, run:

from escpos import config
c = config.Config()
printer = c.printer()

The printer section

The printer configuration section defines a default printer to create.

The only required parameter is type. The value of this has to be one of the printers defined in Printers.

The rest of the given parameters will be passed on to the initialization of the printer class. Use these to overwrite the default values as specified in Printers. This implies that the parameters have to match the parameter-names of the respective printer class.

An example file printer:

printer:
        type: File
        devfile: /dev/someprinter

And for a network printer:

printer:
        type: Network
        host: 127.0.0.1
        port: 9000

An USB-printer could be defined by:

printer:
        type: Usb
        idVendor: 0x1234
        idProduct: 0x5678
        in_ep: 0x66
        out_ep: 0x01

Printing text right

Python-escpos is designed to accept unicode.

For normal usage you can simply pass your text to the printers text()-function. It will automatically guess the right codepage and then send the encoded data to the printer. If this feature does not work, please try to isolate the error and then create an issue on the GitHub project page.

If you want or need to you can manually set the codepage. For this please use the charcode()-function. You can set any key-value that is in CHARCODE. If something is wrong, an CharCodeError will be raised. After you have manually set the codepage the printer won’t change it anymore. You can revert to normal behaviour by setting charcode to AUTO.

Advanced Usage: Print from binary blob

Imagine you have a file with ESC/POS-commands in binary form. This could be useful for testing capabilities of your printer with a known working combination of commands. You can print this data with the following code, using the standard methods of python-escpos. (This is an advantage of the fact that _raw() accepts binary strings.)

from escpos import printer
p = printer.Serial()  # adapt this to your printer model

file = open("binary-blob.bin", "rb")  # read in the file containing your commands in binary-mode
data = file.read()
file.close()

p._raw(data)

That’s all, the printer should then print your data. You can also use this technique to let others reproduce an issue that you have found. (Just “print” your commands to a File-printer on your local filesystem.) However, please keep in mind, that often it is easier and better to just supply the code that you are using.

Here you can download an example, that will print a set of common barcodes:

Advanced Usage: change capabilities-profile

Packaged together with the escpos-code is a capabilities-file. This file in JSON-format describes the capabilities of different printers. It is developed and hosted in escpos-printer-db.

Certain applications like the usage of cx_freeze might change the packaging structure. This leads to the capabilities-profile not being found. In this case you can use the environment-variable ESCPOS_CAPABILITIES_FILE. The following code is an example.

# use packaged capabilities-profile
python-escpos cut

# use capabilities-profile that you have put in /usr/python-escpos
export ESCPOS_CAPABILITIES_FILE=/usr/python-escpos/capabilities.json
python-escpos cut

# use packaged file again
unset ESCPOS_CAPABILITIES_FILE
python-escpos cut

Hint: preprocess printing

Printing images directly to the printer is rather slow. One factor that slows down the process is the transmission over e.g. serial port.

Apart from configuring your printer to use the maximum baudrate (in the case of serial-printers), there is not much that you can do. However you could use the escpos.printer.Dummy-printer to preprocess your image. This is probably best explained by an example:

from escpos.printer import Serial, Dummy

p = Serial()
d = Dummy()

# create ESC/POS for the print job, this should go really fast
d.text("This is my image:\n")
d.image("funny_cat.png")
d.cut()

# send code to printer
p._raw(d.output)

This way you could also store the code in a file and print it later. You could then for example print the code from another process than your main-program and thus reduce the waiting time. (Of course this will not make the printer print faster.)

Troubleshooting

This section gathers various hints on troubleshooting.