A redundant monitoring program based on VC++ and OPC

LIU Rui-xiang1，NI Fu-sheng2，3，GU Ming1

（1. CCCC Tianjin Dredging Co.，Ltd.，Tianjin 300461，China； 2. Engineering Research Center of Dredging

Technology of Ministry of Education，Hohai University，Changzhou 213022，China；3. College of Mechanical & Electrical Engineering，Hohai University，Changzhou 213022，China）

Abstract：Aiming at the low reliability problem of current monitoring system of a sand transport test stand，Siemens software redundancy technology，OPC technology and VC++ programming techniques were researched. The process and characteristics of the communication between the PLC lower machine and the monitoring program which were used in the monitoring system based on Siemens redundancy were generalized. A method was proposed to realize the communication between two monitoring computers and two S7-300 PLC stations

by using OPC technology. The SIMATIC NET software was used to build an OPC Server，and the redundant monitoring program was programed by VC++. The active CPU was identified by the monitoring system by judging the status flags of each active/standby CPU. The data in the active CPU was read and written. The stability and reliability of the monitoring program were tested by fault simulation experiments. The results show that all parameters are monitored in real time，the function of automatic switching of the active/standby system and the fault alarm are realized，and the monitoring system is stable and reliable.