The icusb2321f 1 port usb to serial rs232 adapter cable with ftdi chipset and com retention converts an available usb 11 or 20 port into an rs232 serial db9 port to connect monitor and control your serial devices this compact adapter features com retention allowing the same com port value to automatically be re assigned to the port if the cable is disconnected and re connected to the host computer or if the system is rebooted unlike most of usb to serial adapters this one uses the ftd