ModBus-RTU protocol is a communication protocol widely used in the industrial field, and it is a universal language used in electrical communication terminals. Through this protocol, the inverters can communicate with each other and between the inverters and other devices via the network (such as RS485 bus). It has become a general industry standard. With it, inverter equipment produced by different manufacturers can be connected to an industrial network for centralized monitoring. The protocol describes how the master and slave nodes are defined, the process by which the master node uses various request methods to access other devices, how the slave node responds to requests from other devices, and how both parties detect and record errors. It has developed a detailed definition of the message domain pattern and data content.