This document describes the SmartSDR USB Cable Interface feature that allows band data to be passed to third-party hardware such as amplifiers, antenna controllers, and tuners via USB to Serial cables connected to the USB ports on the back panel of a FLEX-6000. Signals generated by SmartSDR appear on the cable in a form acceptable to the external device in a CAT, BCD or bit format. Included are examples of interfacing the FLEX-6000 with a variety of third-party hardware devices.