Sealevel Systems' 7203e PCI Express Serial Interface
7203e PCI Express serial interface has two optically isolated serial ports, individually configurable for RS-232, RS-422 or RS-485. Each serial port uses a high-performance UART with 128-byte Tx/Rx FIFOs that enables data rates to 460.8 Kbps. The board's 16C952 UART includes 9-bit framing support and is register-compatible with legacy 16550 software applications. The board derives a 62.5-MHz clock from the PCI Express link. In RS-485 mode, the board provides automatic control of the RS-485 driver in hardware, eliminating the need for application software control.