物联网DTU设备时分复用的Modbus报文传输模式

Modbus message transmission mode of DTU equipment in Internet of things based on time division multiplexing

针对物联网数据传输过程中Modbus报文长度限制的问题,提出一种基于时分复用的Modbus从机查询算法。将一个查询周期时长分成若干时隙,在每个时隙分别查询不同的寄存器起始地址及数量,接收端通过每条时隙指令返回的寄存器数量辨识该数据属于哪条指令,实现大量监测值同步实时上传。结果表明,与常规的Modbus查询算法相比,文中算法能突破查询数量的限制。在不增加硬件的情况下,该算法可对信息分布式存储应用场景数据实时查询。

This paper proposes a time-division multiplexing Modbus slave query algorithm designed to address the limitation of Modbus message length in the data transmission process of IOT.The algorithm works on the process by which the duration of a query cycle is divided into several time slots,in each of which,the different starting addresses and numbers of register are respectively inquired;and by which the receiver identifies which instruction the data belongs to by the numbers of register returned by each time slot instruction to achieve synchronous and real-time uploading of a large number of monitoring values.The results show that compared with the conventional Modbus query algorithm,the proposed algorithm can overcome the limitation of the numbers of query;without additional hardware,the algorithm enables real-time query of data in the application scenarios for distributed storage of a large amount of information.