Realization of Serial Port Expansion Circuit

This article describes the design of a interface chip with serial port expansion circuit of computer in industrial applications. It is used to connect with 422 and RS232 interfaces. Circuits involved several major chip such as the interface of 422 and RS232 and UART(Universal Asynchronous Receiver Transmitter)16C550 Inside the computer. Paper describes the composition of the hardware circuit, theory and implementation and initialization programming of URAT interface chip. We use interface chip with the FIFO to the circuit, It improves the efficiency of the application software, And it solves the problem of insufficient of computer serial port.