... RS-232/422/485 port supported Transmission speed up to 921.6 kbps Automatic RS-485 data flow control ... support USB-4604 series allows PC users to connect a serial device to a system that use a USB ... the USB port, so there are no power adapters to deal with. This makes the USB-4604B/4604BM ... , older card solutions. You only have to install the drivers, no need to set cards slots, IRQ addresses, DMA ...