Electrical Parameter Acquisition System Based on S7-300/200 PLC and Modbus Protocol

The paper introduced hardware structure of electrical parameter acquisition system based on S7-300/200 PLC and Modbus protocol and design of program of S7-200 PLC, and expounded process that S7-300 PLC reads electrical parameters stored in S7-200 PLC through MPI communication. The practical application showed that the system is simple and convenient in application, stable and reliable in running, which has certain reference value in engineering.