基于ARM+PFGA的PLC系统通讯设计

Communication Design for PLC System Based on ARM+FPGA

摘要:

为提高PLC系统功能模块间通讯协议的通用性和可扩展性,对自主研制的ARM+FPGA构架小型PLC进行了通讯设计；在分析各类通讯数据的特点、实时性及可靠性要求的前提下,对CAN协议的应用层进行了扩展,采用数据单元法组织通讯数据,并对不同类型的数据定义了不同的数据单元格式,从而制定出了一种CAN扩展协议；另外,提出了以主机为中心的通讯模式,规定了通讯流程,确保了PLC主机执行程序的可靠性；经对通讯可靠性、通讯流量及编解码速度等测试表明,该协议通用性好,编解码效率高,达到了数据可靠传输的目的,提高了PLC系统的性能。

Abstract:

To improve function extension ability and communication protocol generality of PLC system, a communication is designed according to the independent research small PLC based on ARM+FPGA. According to communication real-time and reliability requirements, datas characteristics were analyzed and organized by a method of data unit. Different data units formats were defined. CAN protocol application layer was expanded. CAN extension protocol was formulated. To ensure the reliability of PLC host executing programs, a communication mode with PLC host as the center was proposed, and the communication process was made. The test shows, this extend protocol has a good applicability and high decoding efficiency, realizes reliable data transmission, and improves function expansion abilities.