I am new to using Python and PyUSB. I am trying to write a program to
communicate with a 3M Quest SoundPro sound meter. Because I'm new, I'm
starting simple. The vendor was gracious enough to send me the manual they
have on the commands for the unit. Right now all I'm trying to do is
request the serial number and read the response. I just need to get
communication between a Raspberry Pi and the device working. I have used
the software on a Windows 7 machine along with a USB sniffer to verify the
commands and endpoint address were correct.
This is the program;
import usb.core
import usb.util
import sys
dev = usb.core.find(idVendor=0x130c, idProduct=0x0001)
if dev is None:
raise ValueError('Device not found')
dev.set_configuration()
print "Connected to " + str(dev)
QS = '0x51,0x53,0x0D' #Call for Serial number
dev.write(0x02,QS,0,0)
ret = dev.read(0x82,0x0040,0,1000)
sret=''.join([chr(x) for x in ret])
print "Return Raw: ",ret
print "Return : ", sret
(End of program)
This is the error I get when I run the program:
Python 2.7.3 (default, Mar 18 2014, 05:13:23)
[GCC 4.6.3] on linux2
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART
================================
>>>
Connected to <usb.core.Device object at 0x75176030>
Traceback (most recent call last):
File "/home/pi/qspSLM.py", line 18, in <module>
ret = dev.read(0x82,0x0040,0,1000)
File "/usr/local/lib/python2.7/dist-packages/usb/core.py", line 638, in
read
self.__get_timeout(timeout)
File "/usr/local/lib/python2.7/dist-packages/usb/_debug.py", line 52, in
do_trace
return f(*args, **named_args)
File "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb10.py",
line 493, in bulk_read
timeout)
File "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb10.py",
line 593, in __read
timeout))
File "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb10.py",
line 357, in _check
raise USBError(_str_error[retval.value])
USBError: Operation timed out
>>>
The device has responded twice, both times it was the code that the return
value requested was invalid.
If anyone can help shed light on why this is timing out I would appreciate
it.
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