Design Of Control System Based On Optical Fiber CAN Bus

With the continuous development of information technology, communications technology has been applied to various fields. Some conventional communication standards (eg RS232) can not meet the needs of modern industrial communication. CAN fieldbus its outstanding reliability, flexibility, and efficient real-time data transmission capability, it is widely used in industrial, security and other fields. The CAN bus communication system developed for the detection, monitoring, recording various signals in practical applications have made steady and reliable results. Transmission medium of CAN signal contain twisted pair cable, optical fiber and so on. However, most CAN networks use twisted-pair as transmission medium. So, it’s very important for us to design an optical fiber CAN bus communication system for harsh environments and long-distance transmission.This thesis fiber CAN bus monitoring system, increases the optical fiber CAN signal transmission so that the CAN network can increase transmission distance, improve anti-jamming capability, enhanced corrosion resistance, reduce operation and maintenance costs. It focuses on optical fiber CAN bus hardware circuit monitoring system design. CAN bus system consist of fiber optic repeater, data acquisition and data processing system. The circuits of CAN bus fiber optic repeater are mutually convert CAN signals and optical signals. Optical conversion subject to signal conversion, drive amplifier, in order-to promote the lasers light; Photoelectric conversion need an optical detector and the optical detector receives optical signals into electrical signals, and then the signal processing, the signal is converted to CAN signal. Data acquisition system is to collect sensor data and connect control equipment. It contains STM32 microcontroller, relay circuit, temperature and humidity sensors, ozone sensors, dust sensors, carbon dioxide sensors. Design of data acquisition system has two purposes:first, to facilitate the expansion of more sensors; Second, the sensor of CAN interface is relatively less and the price is more expensive. Data processing system is mainly used for collecting sensor data, control device and display LCD, etc. Besides, SD card is for storing the collected environmental data. Software of this paper contains the data collection of STM32 and CAN communication, to ensure the accuracy of data collection transmission.In this thesis, the construction of the whole system is finished, experiments are carried out to test the design of the proposed scheme. Those experimental results demonstrate that the entire system works stably, which basically meets the requirements of the original design. It has an important significance for optical fiber CAN bus network expansion study.