RS485/422 Solution in Embedded Access Control System

RS422/485 serial bus is widely used in embedded systems for the medium and long-distance data communication. In this paper, the main technologies of RS422/485 bus application in embedded system such as topology, cabling network matching, over-voltage transient protection, earth technology, failure protection and deadlock are elaborated in detail first, then a specific example of embedded access system using RS485/422 is introduced, designing a RS422 and RS485 switch usage hardware solution with only single-driver needed, and reliability of data communication is obtained as well as low software-cost effectively. Keywords-RS422/485 bus; embeded accesss control system; hardware design