Application Research Of PLC In Equipment Monitoring System

Power line high date communication exploits the existing low-voltage distribution network as the communication channel to transfer data signals,which is applied to the broadband access,smart home networking and enterprise internal network,depending on the advantage of better scalability and no need of re-wiring.In the equipment monitoring system,there are two methods to collect the information: active roll polling and asynchronous alarm.Generally,the monitoring system combines the two methods.On the one hand,it obtains the status information with a fixed cycle of polling;on the other hand,it supports asynchronous alarm and the monitored object can report some important message to manager.The paper mainly explores the application of power line communication technology in the field of equipment monitoring system and tries to design a reliable data access for monitoring local area network with PLC's advantage.When a node in the net suffers from fault and needs to report errors to manager,it can transmit the alarm signal to the center exploiting the PLC path,thereby,reducing the complexity of monitoring system.The main research tasks and innovations are as follows:(1)A research scheme is put forward,aiming at solving the problem generated when the power line communication technology is applied in the field of equipment monitoring.According to the research background and the parameter requirements,the research scheme is divided into four parts: channel test,CSMA/CA analysis,hardware design and software test.(2)A channel test scheme is proposed aiming at the actual channel environment.Then a test and analysis are done to the actual power-line about noise,impedance and attenuation.The result shows that the existing noise and attenuation in the channel are the two main factors that affect the quality of communication,which provides a basis for the following hardware design.(3)The CSMA/CA protocol is analyzed for the power line communication in dealing with multiple access.The outcome indicates that CSMA/CA can satisfy the requirements of the bandwidth of each node under the condition that multi-nodes share the same channel.(4)A reliable communication link is designed using QCA7500 developed by Qualcomm in light of the task.Then software is designed to test the link.The result verifies that the designed link could meet the task's needs of bandwidth and reliability.(5)A comparison with CAN is done in specific scene and it presents that PLC has many advantages when applied in the equipment monitoring system,such as high system integration,high speed and flexible networking.