[pyusb-users] Digital Multimeter Output

[Joe <te...@jo...>]

We use two DMMs UNI-T UT61B. They have two interfaces each, a RS232C 
Interface and a USB interface.
The RS232C interfaces work well. Without any command before, the DMMs 
continuously send 2 .. 3 packages of 14 Bytes per second. We get them 
with a little Python 3.52 script, using PySerial. It's ok.

But the younger of our computers have no RS232C comports, and I don't 
want to use virtual comports. So I try to use the USB interfaces of the 
DMMs with PyUSB 1.0, but somethin is wrong with this test script (using 
Win10 Version 1607, 64 bit):

import usb.util
import usb.backend.libusb1

def Gosub():
     failures = 0
     failuresmaximum = 48
     dev = usb.core.find (idVendor = 0x1a86, idProduct = 0xe008) # 
Multimeter UT61B
     if dev == None:
         print ('Multimeter UT61B not found')
     else:
         print ('Multimeter UT61B was found')
         dev.set_configuration (1)
         cfg = dev.get_active_configuration()
         intf = cfg [(0, 0)]
         ep = usb.util.find_descriptor (intf, custom_match = \
                                       lambda e: 
usb.util.endpoint_direction (e.bEndpointAddress) == \
                                       usb.util.ENDPOINT_IN)
         if ep == None:
             print ('ep is None')
         else:
             s = None
             while failures < failuresmaximum:
                 try:
                     s = ep.read (64, 50)
                     print ('Success. len (s): ' + len (s))
                     counter = 0
                 except:
                     failures += 1
             print ('Failures: ' + str (failures))
             if s == None:
                  print ('No data read')
             else:
                for ss in s:
                    print (str (ss)) # Not decoded; just to check: 
something received?

print ('Starting')
Gosub ()
print ('Ready.-')

I get this output:

Starting
Multimeter UT61B was found
Failures: 48
No data read
Ready.-

How to fix - any hint?
Regards - Joe