Along with the development of technology and the serial communication technology is widely used, based on serial communication interface standards, PC and MCU control system is composed by general research and put into use. Based on RS - 232 standards, and on the basis of many other communication interface standards. In the field of industrial control, RS - 485 has become an important means of communication. In practice, RS - 485 criteria displays its good stability and superiority. Taking dc motor control and excitation, with "51" series microcontroller as control core, based on RS - 485 bus, through the design of the PC and man-machine interface control machine working condition, the machine with operation and display function, can complete the data transmission and superordination machine. A key part of the whole system for the PC and the communication, data transmission using CRC checksum. In the system can be used in the factory, the system is more by host and single-chip microcomputer control, the link from the operator can through to host the operation can control all from the machine operation, also from the machine operation, to a host. To achieve "centralized control, independent operation. This can significantly reduce manpower labor, increase production automation degree. Through the study of this system, overall design, the system can realize data transmission, right of PC machine control
