Startech com pex4s232485 pci express 2xrs232 2xrs485 combo card startech com pex4s232485 p the pex4s232485 4 port pci express pcie serial combo card from startech com lets you add two rs232 and two rs422 485 serial ports to your pc through a pci express expansion slot p p this pci express serial card is a single card solution which is compatible with nearly any serial communication protocol supporting rs 232 rs 422 rs 485 2 wire or rs 485 4 wire operating modes p p the 4 port ser