The data transmission on CAN bus is decided by priority, That is the data with high priority can always be transmited by inturrupt the data transmission with low priority .In that case the data with lower priority may not be transmitted for a long time .To sove such problem we use DRR scheduling algorithm ,But in the case of too many unexpected data ,The scheduling results are poor .In view of such situation this paper put forward a solution allocation quotas dynamicly according to the current network state . And setting up a CAN bus system simulation platform in which conducted a simuliation experiment.The result show that the improvement strategy work well at any situation.

Controller Area Network (CAN) is widely used in real-time automobile control and is gaining wider acceptance as a standard for factory automation. This paper discusses the applicability of Rate Monotonic (RM) techniques to the scheduling of CAN messages. Rate Monotonic can guarantee higher network utilization, but it is difficult to implement in periodic data networks or local buses. The paper mainly analyzes the RM scheduling algorithm and then establishes the simulation model about the algorithm based on CAN bus, and analyzes the effect in this situation of experiment.