There're several sets of coal handling program control systems during phased construction of large thermal power plants. Centralized control and resources sharing can't be achieved among various systems due to using different brands of programmable logic controller(PLC). By taking the intercommunication between the first phase and second phase coal handling program control system of a power plant as the example

the Micro Logix 1400 PLC is used to transform the communication protocol based on analyzing the control characteristics of Control Logix PLC system and Quantum PLC system

and the architecture of intercommunication network is constructed based on Modbus/TCP and Ethernet/IP protocol. After address planning of each PLC in compiling software

the switching values of control equipment are combined into 16-bit control word by using data type converting function block of Quantum PLC. Then

the control words set by Quantum PLC are read and written by Micro Logix 1400 PLC through MSG module. After that

the Micro Logix 1400 PLC can communicate with Control Logix PLC

thereby achieving the data exchange between Control Logix PLC and Quantum PLC. It enables the information sharing and equipment interconnection between the two sets of coal handling control systems. After three years of actual operation

it shows that the intercommunication network has features of fast response speed and accurate date reading

which greatly improves the reliability and production efficiency of coal handling system.