基于CAN网络的嵌入式软PLC系统环形缓冲研究

Research of circle buffer of embedded soft PLC system based on CAN network

为降低嵌入式软PLC系统传输数据的误码率和丢包率,设计了嵌入式软PLC系统的环形缓冲区,建立了环形缓冲区数学模型,分析得到了环形缓冲区的状态方程、状态转移概率及其容量和被充满的概率通式。利用仿真得到不同条件下影响缓冲区容量大小的因素,得出在无数据丢失的前提下,缓冲区大小与数据输入流和输出流两者差值的关系:在其他条件不变的情况下,输入流速率与输出流速率的差值越大,所需要的环形缓冲区容量就越大。

To reduce the error rate and packet loss rate of transmission data in embedded soft PLC system, a circle buffer of embedded soft PLC system was designed, mathematical model of the circle buffer was established. The state equation and the state transition probabilities of the circle buffer were analyzed, and its capacity and the formula of probability of being filled were also discussed. At last, the factors affecting the size of the buffer capacity under different conditions were obtained by simulating, and the relation of data buffer size and the difference between the input stream and output stream were concluded under the premise of no data loss： in the case of other conditions unchanged, the greater the difference between input stream rate and output stream rate, the greater the needed capacity for circle buffer.