Research And Application Of Control-Network In Visual-speaking Systems In The Uptown

In order to construct low-priced, reliable visual-speaking systems in the uptown,to meet the demands of safety and information management in the intelligent uptown,I studied the fieldbus technology and one of its solutions-CAN technology. Base on our country condition of intelligent building system and development tendency in the future, I made a design and improvement of CAN+RS485 bottom network, to achieve a intelligent control network of uptown safety and signal transmission.This model is base on CAN technology. The uptown CAN network uses CAN+RS485 double deck network structure. The upper layer of CAN network is composed of many nodal points, which include central control units, gate control units and landing door control units; The lower layer of RS-485 network include landing door control units, landing door units and inhabitant control units. The two layers network connected by landing door control unit, to realize the functions of management, control, alarm, signal collection and self-examination.An improvement of RS-485 control network has been put forward and held up RS-485 coequal dynamic time control multiple computers communication in this paper. The dynamic time control is proved to enhance highly network communication ability compared with fixed-time delay, and meet with the needs of visual-speaking systems, also can used in other conditions of RS-485 multiple computers communication.