Tried to read 1024 byes, however, still the timeout error.
-------------------------------
Traceback (most recent call last):
File "code.py", line 15, in <module>
received = dev.read(0x81, 1024, 0, 5000)
File "C:\Python26\lib\site-packages\usb\core.py", line 624, in read
self.__get_timeout(timeout)
File "C:\Python26\lib\site-packages\usb\_debug.py", line 53, in do_trace
return f(*args, **named_args)
File "C:\Python26\lib\site-packages\usb\backend\libusb01.py", line
448, in bulk_read
timeout)
File "C:\Python26\lib\site-packages\usb\backend\libusb01.py", line
531, in __read
timeout
File "C:\Python26\lib\site-packages\usb\backend\libusb01.py", line
364, in _check
raise USBError(errmsg)
usb.core.USBError: libusb0-dll:err [_usb_reap_async] timeout error
---------------------------------------------------------------
Could it be related to com port opening or baudrate?
I notice that this code stops timing out the moment manufacturer's
demo application opens the com port explicitly. Also, if I set a
baudrate higher than 9600 to the reader, I start receiving the
complete data.
Any help/insight?
Sridev
On Mon, Jan 3, 2011 at 4:36 PM, wander.lairson <[email protected]> wrote:
> 2011/1/1 Sridev Nair <[email protected]>:
>> Hi,
>>
>> I have been working with pyUSB (Python 2.6) for last couple of days on
>> Windows. It works great and I could access the auto-id reader within
>> no time. However, there is this read command timing out issue which I
>> am unable to resolve. In fact it is a bit weird since it seem to work
>> when I parallely run the demo application of the same reader provided
>> by the manufacturer. The device driver spec, code & error output are
>> below.
>>
>> Any help in solving the problem?
>>
>> Sridev
>>
>> ---------------------------device specs-----------------------
>>
>> Device:
>> Device class: 0
>> Device sub class: 0
>> Device protocol: 0
>> Max packet size: 64
>> idVendor: 4292
>> idProduct: 33266
>> Device Version: 256
>> Configuration: 1
>> Total length: 32
>> selfPowered: 0
>> remoteWakeup: 0
>> maxPower: 200
>> Interface: 0
>> Alternate Setting: 0
>> Interface class: 255
>> Interface sub class: 0
>> Interface protocol: 0
>> Endpoint: 0x81
>> Type: 2
>> Max packet size: 64
>> Interval: 0
>> Endpoint: 0x1
>> Type: 2
>> Max packet size: 64
>> Interval: 0
>>
>> ----------------------------code--------------------------------
>> import usb.core
>> import usb.util
>>
>> dev = usb.core.find(idVendor=0x10c4, idProduct=0x81f2)
>>
>> if dev is None:
>> raise ValueError('No Device')
>>
>> dev.set_configuration()
>>
>> msg = [0x03, 0x02, 0x00, 0x03, 0x07, 0xD0, 0x03]
>>
>> bytes = dev.write(0x01, msg, 0, 2000)
>>
>> received = dev.read(0x81, bytes, 0, 5000)
>>
> Try to read about 1024 bytes, instead of the same data read. If there
> is more data in the device buffer than you ask for, this may happen.
>
> --
> Best Regards,
> Wander Lairson Costa
> LCoN - Laboratório de Computação Natural - Natural Computing Laboratory
> (http://www.mackenzie.com.br/lcon.html)
> Programa de Pós-Graduação em Engenharia Elétrica (PPGEE)
> Faculdade de Computação e Informática (FCI)
> Universidade Presbiteriana Mackenzie - SP - Brazil
>
> ------------------------------------------------------------------------------
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