Study And Implementation Of The Key Technologies Of High Precision Acquisition And Transmission Device Based On CAN Bus

According to the task needs for an aerospace measurement and control system, the High precision acquisition and transmission device is designed based on CAN bus which includes the acquisition converter and the repeater.The acquisition converter via CAN bus implements the network connection for the sensors networking in the acquisition field to achieve the precision real-time acquisition of analog quantity in the sensors distributed system.Due to the limit of CAN bus transmission distance, the repeater achieves the function of long-distance transmission. The key technology of the design and study are the high acquisition precision and the high reliability.Firstly,this paper not only takes the circuit design, hardware selection and layout into consideration but also designs reasonable and flexible digital filtering algorithm for noise reduction processing of the sampled data according to the actual characteristics of the source of interference to improve the acquisition precision. What’s more, it also uses the least squares method to correct and compensate the acquisition error. Secondly in order to ensure the reliability of the work of the acquisition and transmission device, the device was optimized from the following aspects:CAN physical layer, dual-standby redundancy of CAN bus, CAN bus utilization improved, RS422 interface circuit, fault handling mechanism and the reliability of the acquisition command and so on.Finally, the precision and reliability of the acquisition of the transmission device are verified in conjunction with the supporting test bed and the PC software in in a variety of harsh environments, such as High temperature, electromagnetic interference, vibration, and low air pressure. The test results showed that acquisition and transmission device meets the requirements of environmental adaptability. It works stably and reliably with the high acquisition precision of 0.2‰.