The Design And Research On Communication System Of The Control Network Of Intelligent Building Based On Power Line Transmission

Intelligent building is the concernful research in nowadays and the control network is the basic of the Building Automation System (BAS) of the intelligent building. So the research on the communication system of the control network is significant to the BAS, even the whole intelligent building. This paper investigates the communication system of the control network of intelligent building based on power line transmission and its hardware and software realization.Contraposing the characteristics of the power line, this paper brings forward some measures to improve the quality of the power line communication (PLC), and these measures are applied in the hardware design of the system. All kinds of PLC technologies are introduced and a comparison of performance between Spread Spectrum and Orthogonal Frequency Division Multiplexing in PLC is carried out. The Direct Sequence Spread Spectrum technology that is adopted by the PLC modem in the system is amply discussed.The collector and the communicator are communication nodes of the system. They enable the control network to pass the information and commands through power line. Depending on the idea of modular design, the communicator is decomposed to PLC module, MCU module, power and coupling module, while the collector has one more module: RS-232C interface module. The SC1128 of the Beijing ZYLH Company is adopted as the corechip--PLC modem of the PLC module. The hardware realization of every module isdiscussed in the paper.Excellent communication protocol and software design is also a guarantee to an effective and credible communication system. The communication protocol is designed in term of three layers: Physical Layer, Media Access Control Layer and Logic Link Control Layer. Considering the exigency of the security information in the control network, a CSMA/CA protocol with priory and adaptability is proposed as media access control method. The main task of the software design is to realize the communication protocol and the flows of several important subprograms and the main program of the communication nodes are given in the paper.The PLC performance of the communication nodes is tested and analyzed. The results show the communication system of the control network of intelligent building is feasible.