西门子S7-200 Smart PLC与V20变频器的通信实现——基于Modbus RTU通信协议

Realization of Communication between Siemens S7-200 Smart PLC and V20 Inverter——Based on Modbus RTU Communication Protocol

Modbus RTU通信协议是一种通过远程终端单元实现Modbus通信的新型协议,可简单、方便地将工业仪表、设备组成通信网络,实现启停控制、频率设定、数据监控等操作。对Modbus RTU通信报文结构进行分析,明确其通信机理;以西门子S7-200 Smart PLC作为主站,西门子V20变频器作为从站,组建了硬件系统;详细研究将Modbus RTU通信协议应用于工业系统主站与从站实现通信的方法。以主站初始化为起点,分析主站读写、变频器控制、频率设定、变频器参数读取等环节,提出了主站PLC程序编写思路,实现了对从站变频器的控制和监控。设计思路将帮助工业企业有效提高工业仪表互联互通效率,对工业企业智能化改造起到有效的帮助作用。

Modbus RTU communication protocol is a new protocol to realize Modbus communication through Remote Terminal Unit,which can simply and conveniently form industrial instruments and equipment into a communication network to realize operations including start-stop control,frequency setting and data monitoring.The message structure of Modbus RTU communication is analyzed,and its communication mechanism is clarified.With Siemens S7-200 Smart PLC as the master station and Siemens V20 inverter as the slave station,the hardware system is established,and the implementation method of applying Modbus RTU communication protocol to the communication between the master station and the slave station of industrial system is studied in detail.Starting from the initialization of the master station,the idea of PLC programming of the master station from analyzing the links of reading and writing of the master station,inverter control,frequency setting and inverter parameter reading are put forward,and the control and monitoring of the inverter of the slave station are realized.The design ideas will help industrial enterprises effectively improve the efficiency of interconnection and intercommunication of industrial instruments,and play an effective role in the intelligent transformation of industrial enterprises.