Add two rs232 and two rs422485 serial ports to your pc through a pci express expansion slot the pex4s232485 4 port pci express pcie serial combo card 2 x rs232 2 x rs422 rs485 lets you add two rs232 and two rs422485 serial ports to your pc through a pci express expansion slot this pci express serial card is a single card solution that is compatible with nearly any serial communication protocol supporting rs 232 rs 422 rs 485 2 wire or rs 485 4 wire operating modes a flexible