Triggers are developed for indicating the presence of non-recoverable
and/or recoverable loss of communication situations between a device and
device driver software using universal serial bus (USB) protocol. We
modify the firmware at the device in order to monitor for the triggers
and control the device in specified ways once a trigger is indicated. In
a particularly preferred embodiment the device is a motorized card reader
in a self-service terminal and the device is arranged to return a smart
card when a trigger is detected. In one embodiment the trigger is
associated with the presence of a single ended zero condition on the USB.
In another embodiment the trigger is associated with attempts to
re-enumerate the device over the USB.