Design Of Real-Time Monitoring & Control System For Controlled Atmosphere Storages

With the rapid development of fruit and vegetable industry in China, the fruit and vegetable storage technology has provoked an intense interest. Over the past few years, a plenty of money has been spent in importing mechanical refrigerator instruments, and more than one hundred controlled atmosphere storages have been built in our country. However, many of these storages were not been used in practice and some of them have been losing their storage ability in these days because of an unfit device and a low management level. Therefore, it is only when a fit controlled atmosphere storage was designed that the problem of fruit and vegetable storage could be solved.There are four controlled atmosphere storages in Shanxi Tianfu Fruit Limited Company. The controlling system of these storages has been out of date and it was hard to operate. To improve the automation and management level, a suitable controlling system was designed in this study on the original controlling system.The system could measure real-timely the environmental parameters of carbon dioxide, oxygen, temperature and humidity; control the gas components in the CA simultaneously to keep an optimal storage environment.The system hardware was composed of upper computer and lower computer. The upper computer, PC microcomputer, was the headquarters of the system. The lower computer, 8098 single-chip microcomputer, was the collection and control station. Serial communication between upper PC and lower computer was realized by RS-232 Lines of Communication. By serial communication, data collected by 8098 was transferred real-timely to PC and was displayed, saved, printed and managed in PC. Simultaneously, the 8098 single-chip microcomputer sent out controlling signals to drive the relay.The system software included upper computer system software and lower computer system software. Method of structural module was adopted in the design of the system software. The upper computer system software was developed with VB and composed of five modules, such as setting of parameters, real-time monitoring and collecting data, reproduction of history data and help module. Each module has certain function and could visit to other modules. The lower computer system software was developed with 8098 assemble language of MCS-96 series and composed of modules of main program, time interrupt service routine, receiving interrupt service routine, data collection subroutine, data processing subroutine and control subroutine.The system has a favorable operating environment and friendly interface; and it was easy to operate, upgrade and extend.