Research And Design Of Intelligent Building Electrical Monitoring System Expansion Layer

With the rapid development of society and technology,a great deal of information is constantly produced,so the requirements for information management efficiency are increasing.The information integration development of intelligent building electrical monitoring system is an inevitable trend of efficient management of information and rational allocation of resources.At present,the types of networking technologies used in the intelligent building electrical monitoring system are complex and the technical barriers are high.The incompatible communication protocols between the subsystems cause difficulty in integration and interoperation.The independently developed L-N field bus technology already has its field layer communication protocol and electrical monitoring protocol,and can be customized according to user needs as a specific functional subsystem.In order to solve the problem of the integration of many independent subsystems,this paper designs the intelligent building electrical monitoring system expansion layer.The system is divided into field layer and expansion layer.The smallest element in the field layer is a node.Nodes can monitor a variety of electrical devices such as power switches,sensors and relays connected to them,and send or receive field layer messages through the L-N bus.Each L-N bus constitutes a group that managed by a group adapter.Multiple group adapters are mounted on the CAN bus and form an expansion layer with an integrated gateway.The expansion layer protocol not only carries the task of transmitting the field layer messages,implements the interactive control and feedback of information between any subsystems,but also has independent expansion layer fuctions such as segment transmission,message broadcast,CAN bus error management,group adapter information monitoring and configuration.Aiming at the problem of memory consumption in general segment transmission mode,a packet segment transmission method with dynamic priority is designed.This method implements rapid reassembly of packet fragmentation and reduces the memory resource overhead.The group adapter uses a STC12C5A60S2 chip as the microcontroller.It analyzes the received expansion layer message.If the message needs to be forwarded,the group adapter translates it to the field layer message and sends it to nodes.If the message contains the management command for expansion layer independent function,then the group adapter executes it.The integrated gateway uses a STM32F407ZGT6 chip as the microcontroller.It communicates with group adapters through expansion layer messages,and communicates with the user by text messages through via a TCP/IP protocol-based server or by USB messages via USB bus.It also follows the expansion layer protocol to monitor the working status of each communication interface and the online information of the group adapters in real time,and display all of the information on the LCD.Aiming at the problem of multi-network integration and communication protocol interaction,a multi-protocol conversion task management method is proposed,which achieves interoperability between multiple protocols.Results of group adapter and integrated gateway communication interface special tests show that the communication interfaces are stable and reliable.Protocol conformance test results show that the expansion layer protocol stacks running in the group adapter and the integrated gateway are highly consistent and that the expansion layer protocol is fully functional.The results of system application tests show that the expansion layer is able to carry all the field layer message transmission,and with high subsystem interoperability and strong multi-protocol interaction ability.