基于MODBUS的GCAN PLC与变频器通讯系统

MODBUS-based Communication Systembetween GCAN PLCs and Frequency Converters

针对PLC开关量输出驱动中间继电器控制变频器时无法取驱动电机参数问题,运用Open PCS编程软件,设计一套基于MODBUS协议的GCAN PLC与变频器的RS485通讯系统,不但能完成传统应用的所有功能,还能进行内部数据通讯,可方便地从变频器中获取所驱动电动机各种参数如:运行频率、电流、电压、功率等等。经过通讯调试,采用MODBUS协议,GCAN PLC通过发送MODBUS报文可以给定频率控制变频器的启停,同时可以读取电动机的相关数据,实现GCAN PLC与变频器的通讯功能。

A MODBUS-based RS485 communication system between GCAN PLCs and frequency converters is designed with Open PCS programming software to solve the problem about failure to take the data of motors when frequency converters are controlled by intermediate relays driven by the on-off output from PLCs.In addtion to the all conventional functions,the communication system can carry out internal data exchange and obtain various motor data from frequency converters,such as frequency,current,voltage,power and so on.Based on MODUBUS protocal,GCAN PLCs can send messages through MODBUS to set the ON/OFF of frequency converters and also read the pertinent data of motors so as to realize the communication with frequency converters.