... port models require no external power. Modelswith USB output ports use an included power supply. Features 1, ... 2, Add 1 to 4 serial ports 3, Multi-interface RS-232 model 4, USB 1.0 and 1.1 compliant; USB 2.0 backwards compatible 5, USB ... port powered- no external power needed on USB ... -04-24 04:52:58 USB to 4 Ports RS232 Converter-USB4232