Study Of Communication And Real-time In CAN Net

CAN bus has now become a widely used field bus, which has an ideal real-time and reliability, and network flexibility, used in many fields. CAN is the most influential one of field bus.This article describes the CAN bus protocol specification, based on its medium access control method, implement the CAN communication by the ECAN module and the DMA controller of microchip dsPIC33FJ256GP710 devices.Establishmented the mathematical model of delay time of CAN bus messages, by analyzing the causes of messages delay. Introduced the research of CAN bus real-time performance and some common solutions. And in accordance with the principle of dynamic changeing the priority to improve real-time performance, design a "mod upgrading" of the dynamic priority scheduling algorithm, and using software to achieve.Due to the current CAN bus simulation study achieve by the hardware simulation, using network simulation software OPNET, a three-tier model, adopting CSMA/CD bus arbitration to achieve software simulation of CAN and analysis the performance of the CAN network.The study provides a new choice.