def getHandleToLowSpeedDevice(vencor_id, device_id):
# find the device
device = LibUSB.get_device_with_vid_pid(vendor_id, device_id)
if device is None:
raise Exception("unable to find X10 device")
LOGGER.debug("found X10 device")
# the cm15 is a low speed device (1.5MBit/s) which means that its
# maximum data payload is 8 bytes per transfer
assert(device.device_speed() == LibUSB.SPEED_LOW)
# open the device:
dh = device.open()
LOGGER.debug("opened a handle to the device")
return dh
