I apologize for my question that is obvious to others, but I am a new Flex owner. I am trying to interface a Flex6500 to an Expert Amplifier. I have built the cable to connect between the Expert and the USB-Serial interface. I went to the Flex 6500 manual to understand how to use the USB ports and it refers me to the SmartSDR manual. I checked the SmartSDR manual and it refers me to the USB manual which I have. I have 3 different USB-Serial devices. When I plug them into the 6500, should they show up immediately in the USB cable menu in SmartSDR software? I have tried all 3 cables and nothing shows up. Does that mean they are not FTDI? I have no way of checking them, but they work fine if I connect them to a Windows10 USB port. Is there somewhere else in the software that I have to activate the USB ports? Set up a CAT port? The USB manual assumes the adapters are listed in the USB Cable menu, but nothing shows up. Any advice would be appreciated.