The MESA 5I21RL-ROHS custom board is a programmable serial interface card for the PCI bus. The 5I21 is designed for applications using RS-422 and RS-485 interfaces. The 5I21 can support up to 12 full duplex RS-422 or half duplex RS-485 serial links with baud rates up to 10 M baud. The 5I21 uses a 400K gate Spartan3 FPGA and a bus mastering PCI bridge for high performance. Since all serial logic is FPGA based, almost any RS-422/RS485 protocol can be supported.