Research And Implementation Of BACnet MS/TP Control Module In Smart Building

With the improvement of people’s life quality, there is a increasingly wideapplication of intelligent buildings. As the only international standard in buildingautomation, BACnet is used widely in global. MS/TP is an option of data link layerof BACnet, MS/TP is widely used in the field building automation equipmentbecause of its low cost and easy using. MS/TP is a specifically for buildingautomation development, using token ring mechanism to realize master-slave/token-passing control.Firstly, this paper discusses the system structure, service and object of BACnetprotocol. The paper also focused on the MS/TP state machine. Secondly, the paperstudied medium access control algorithm, including algorithm of token passing,multiple tokens detection and token generation.Then, the traditional MS/TP MAC address assignment has the problem ofmanual mistaken, which on some degree constraints MS/TP devices’ using. Thispaper focuses on the study of an automatic dynamic addressing algorithm, whichcan reduce hardware cost and have little affect on the network bandwidth, the mostimportant benefit is to decrease the manual mistake operation and manpower cost.Through the analysis of Wireshark message in test could verify the automaticaddressing algorithm.Finally, this thesis designed a MS/TP field control module using in smartbuilding in terms of the input power supply, communication interface, a relay driveand load detection circuit design, and giving a detailed schematic diagram. Inaddition, the BACnet protocol and MS/TP protocol using in the module aredescribed. Through VTS testing of BTL, the control module conforms to theBACnet conformance requirements.The MS/TP control module designing is a direct digital control equipment(DDC) used in intelligent building.Connecting with the other BACnet devices, canform a complete set of building control scheme. It helps to promote the applicationand development of BACnet in China.