How to get data from a barcode reader using raw data mode and pyUSB?

Question

I need to read a barcode data using a usb barcode reader (raw data mode). I already know that I can set the reader with the keyboard mode but it just doesn't fit my requirement because I'll be using 4 readers simultaneously and the text will overlap.

I am new to python and i've tried researching it myself to no avail. I got these idea through the documentation and I really don't know what's wrong with it.

Here's the sample code that i've come up so far:

import sys
import usb.core
import usb.util

# got these using the command lsusb -vv

VENDOR_ID = 0x4b4
PRODUCT_ID = 0x100
DATA_SIZE = 1

device = usb.core.find(idVendor=VENDOR_ID, idProduct=PRODUCT_ID)

if device is None:
    sys.exit("Could not find Id System Barcode Reader.")

if device.is_kernel_driver_active(0):
    try:
        device.detach_kernel_driver(0)
    except usb.core.USBError as e:
        sys.exit("Could not detatch kernel driver: %s" % str(e))

#not really sure if these are correct configuration.

try:
    cfg = device.get_active_configuration()
    for i in cfg:
        for x in i:
            x = x
    device.set_configuration()
except usb.core.USBError as e:
    sys.exit("Could not set configuration: %s" % str(e))

data = []
swiped = False 

#i can't print the data when i try to read a barcode


data = device.read(x.bEndpointAddress, x.wMaxPacketSize, 0, 10000)
print data

After running this and trying out a barcode i get this error.

Traceback (most recent call last):
  File "barcodesensor.py", line 37, in <module>
    data = device.read(x.bEndpointAddress, x.wMaxPacketSize, 0, 10000)
  File "/usr/local/lib/python2.6/dist-packages/usb/core.py", line 654, in read
    self.__get_timeout(timeout)
  File "/usr/local/lib/python2.6/dist-packages/usb/backend/libusb10.py", line 559, in intr_read
    timeout)
  File "/usr/local/lib/python2.6/dist-packages/usb/backend/libusb10.py", line 641, in __read
    timeout))
  File "/usr/local/lib/python2.6/dist-packages/usb/backend/libusb10.py", line 403, in _check
    raise USBError(_str_error[ret], ret, _libusb_errno[ret])
usb.core.USBError: [Errno 110] Operation timed out.

I am willing to donate via PayPal to anyone who can help me in obtaining the raw data and converting the format to string. Thanks in advance.

EDIT: How do I obtain the correct data from the barcode and convert it to the readable string format?

How do I obtain the correct data from the barcode and convert it to the readable string format? — Angelica Lim, Aug 16 '12 at 00:50
Please don't tag your questions with paypal unless they concern using paypal API or something like that. — Ihor Kaharlichenko, Aug 16 '12 at 01:00
sorry, its my first time asking a question. thank you for the reminder. — Angelica Lim, Aug 16 '12 at 01:39

score 0 · Answer 1 · answered Aug 16 '12 at 00:59

0

Extracting the textual data from the USB payload is vendor specific. So you will need to figure that out on your own, though it isn't too complicated.

As for the exception you get, try to enable debug logging, run your script again and post the content on pyusb.log.

To enable debugging set a couple of environment variables as described in the What's wrong? section of the tutorial.

For Linux/Mac:

$ export PYUSB_DEBUG_LEVEL=debug
$ export PYUSB_LOG_FILENAME=pyusb.log

For Windows:

> set PYUSB_DEBUG_LEVEL=debug
> set PYUSB_LOG_FILENAME=pyusb.log

answered Aug 16 '12 at 00:59

Ihor Kaharlichenko

5,944
1
26
32

sorry, i tried running the export PYUSB_DEBUG_LEVEL=debug and export PYUSB_LOG_FILENAME=pyusb.log in the terminal before running the script. but it doesn't seem to create this pyusb.log file – Angelica Lim Aug 16 '12 at 01:22
Then try a different, better absolute path, i.e. /tmp/my.log. – Ihor Kaharlichenko Aug 16 '12 at 01:23
i tried the absolute path but to no avail. export PYUSB_LOG_FILENAME='home/techlab/Dropbox/IdSystem/practice/pyusb.log' – Angelica Lim Aug 16 '12 at 01:26
i tried using logging module then logging.basicConfig(), still doesn't catch the error. – Angelica Lim Aug 16 '12 at 01:30
@AngelicaLim Did you miss type your path in the comment? It is missing the first '/'. – Echo says Reinstate Monica Aug 16 '12 at 02:03

score 0 · Answer 2 · answered Jul 07 '14 at 08:54

0

The reason you can't get the debug is because the environment variable is PYUSB_DEBUG not PYUSB_DEBUG_LEVEL.

Try this:

export PYUSB_DEBUG=debug
export PYUSB_LOG_FILENAME=pyusb.log

python yourscript.py

nano pyusb.log

answered Jul 07 '14 at 08:54

Daniel van Flymen

10,931
4
24
39

score 0 · Answer 3 · answered Sep 10 '15 at 14:45

Can try out installing the pyusb from the git mentioned below

https://github.com/walac/pyusb#installing-pyusb-on-gnulinux-systems

The above program worked just by reducing the arguments in the device.read()

replace data = device.read(x.bEndpointAddress, x.wMaxPacketSize, 0, 1000) by data = device.read(x.bEndpointAddress, x.wMaxPacketSize)

How to get data from a barcode reader using raw data mode and pyUSB?

3 Answers3