The Next Gen XG-PCS-IC-1 PCS Data Interface Cable consists of a USB connection on one end, and a RJ-11 connection on the opposite end.
The USB connection plugs into an available USB port on your PC. The RJ-11 connection plugs into the RJ-11 "OUT" Jack (labeled "Data Port") on the Next Gen PCS Filter, which is the jack closest to the LCD Event Monitor and RST button.