The Design Of Large-scale Remote Monitoring Network Based On CAN Bus

At present, China is building a number of deep gorge hydropower stations. The complex geological conditions and the slope stability problems are the common technical problems in the these projects. Safety monitoring is the effective means of keeping the slope stability. However, the monitoring of the slope, with its speciality, is definitely different from that of the dam, hence of the technical problems existing in the automated monitoring need to be overcome.In this paper, a large-scale remote monitoring and control network system is designed for the high slope on the right bank of the Qinghai Laxiwa dam for the need of safety monitoring. The system deals with communicative system, upper software, which are the focus of this paper, and bottom measure module.The high slope safety monitoring system for the specificity of the Qinghai Laxiwa dam has been considered, and it needs lots of measuring points as well as equipments, and the distances between the measurement equipments are long, far away from the main control room(5Km). So in this paper, the CAN bus is selected as the communication protocol. The functions are: 1. The command of the top users will be sent to the bottom module; 2. The data collected by the bottom measurement modules will be transmitted to the upper management software accurately, for the analyzing and processing.Focusing on the network module for communication system design, this paper will introduce the hardware and software design of this modular. On the hardware design aspect, the C8051F040 microcomputer is selected as the core of the communication control system. Certain new, high-speed, powerful-function chips are also used for the reasonable, easy and reliable design consideration. Because the covering area of the Qinghai Laxiwa dam is large(10Km×10Km), in order to improve anti-jamming communication system of the network and to ensure appropriately high-speed communications, we increase the number of the repeaters in the network. In this paper, it is the first time that in the network communication system, we amplify the signal in the communication channel using CAN network repeater module based on dual MCUs using SPI, and for the routing and forwarding of the data packet. This method is still in experiment nowadays, but it is of great significance. On the software design aspect, according to CAN2.0A, CAN2.0B and SPI protocol specification of the full use of the frame format message, the communication protocol is designed to complete the master node, relay nodes and the underlying communication software design of communication. On the upper management software aspect, this paper describes the relevant content of serial communications.In addition, through the equivalent circuit analysis of the remote network, simulation of the long-distance circuit structures, and test the designed system, the results show that there is no packet loss, as well as the success of 76ms to send data and to receive. Using the repeater we can successfully send and receive data through a distance of 138ms. The test results show that the communication system has a good stability and real-time feature and has basically met the need of the high slope safety monitoring system.