Review on Waveshare USB to RS232/RS485/TTL Industrial Isolated Converter with FT232RL Protection Circuits and Aluminium Alloy Enclosure for Industrial Control Equipments: Enhanced Connectivity and Safety by Don Wilson

Amazing that you can get real isolation for this price. this. avoids problems with ground loops/ground level differences between devices. I opened the case and looked at the board, it has a DC isolator for power supplies as well as the expected isolation barrier for signals. The board had a very noticeable cut/split groove where the insulation goes from the USB side to the serial connector side. (The RS-232/RS-485 serial ports aren't isolated from each other, but that's ok since only one of them is meant to be used at a time. This is because it's a USB host-to-serial adapters, so USB/PC are isolated.) Also, the FTDI USB/Serial chipset is fairly easy to install on Windows (Microsoft will detect the driver and load it automatically). So far, all 3 interfaces (RS-232, RS-485, TTL) have worked perfectly for me. I expect to use TTL for devices like the Raspberry Pi that don't deal with transceivers.