This product is a PCI bus-supported card designed for extending RS-422A/485 compatible serial communication functionality on your PC. It has four RS-422A/485-standard serial ports. Higher noise-resistant models with isolation between channels and between PC and bus line as well as a surge protection circuit for communication ports. With a 128byte built-in FIFO buffer for transmission and reception of each channel, the product supports a baud rate of up to 921,600bps. It also comes with a Windows/Linux driver, which allows cards to be used as OS-standard COM ports.