The board is for FTDI's popular USB to UART IC. Now with internal oscillator and EEPROM, the FT232RL is an impressive IC.It is open source so driver is available for Windows,Linux and Mac OSX
This is a simple RS232 to RS485 converter that is self powered using the TX, RX or RTS, CTS signals for power. The RS232 is DB9 female connector, and the RS422 side is a DB9 male or 4 position terminal block.