ThingMagic Autonomous Configuration Tool - Manual (Page 7)

Autonomous Reading Overview
Autonomous Configuration Tool v1.0 User Guide 7
USB I/O Specific Notes
 
When connected via the USB interface the reader will buffer tag reads if the USB
connection is lost or not established. This will eventually cause the buffer to fill
and the reader to throttle reading until a USB connection is made and tags can
be offloaded and reading started again.
TTL/UART I/O Specific Notes
 
When connected via the TTL/UART interface the reader cannot detect whether a
connection exists or not. This means data does not get buffered due to detecting
a missing connection as they do with the USB interface. As a result if a
connection is lost or none is established the reader will continue reading and
streaming results, which will be lost.