The USB-RSAQ3 is a blue adapter that converts USB to RS-232C. - Brand: I-O DATA - Model Name: USB-RSAQ3 - Cable Type: USB to RS-232C - Color: Blue - Connector Type: RS-232C Thank you for viewing. IODATA USB-RSAQ3 RS232C USB Conversion 中古 (Used) It's old, but still usable. Includes a 2m USB cable. Reference to manufacturer's documentation: The "USB-RSAQ series" is a conversion adapter that allows you to connect RS-232C devices via USB. You can use it with modems and terminal adapters, which are typical RS-232C connections, as well as digital cameras and PDAs. It supports DTE speeds up to 230.4Kbps, maximizing the performance of terminal adapters. In addition to simply replacing the connection port, there are USB-specific advantages that were not available with RS-232C connections, such as "not consuming system resources" and "relaxed limitations on the number of connected devices." It supports Windows and macOS X, so you can use RS-232C devices even on the latest MacBook Pro and Mac mini, which do not have RS-232C ports.