Abstract: In order to solve the problems of traditional greenhouse, such as low automation level, inconvenient
maintenance and low profit, an intelligent greenhouse system is proposed based on distributed control theory. The
AT89C51 microcontroller is used as the lower computer, which can constantly monitor greenhouse environmental
data. When these sensors gain environmental data, the lower computer can process data and control the whole
system. Then these data are transmitted to the host computer for processing through RS-485 bus. A friendly
human-computer interaction interface is designed in the host computer by KingView 6. 55 software. Through the
human-computer interaction interface, the host computer controls several the slave computers to realize different
functions including storing data and adjusting the parameters. The fault of one slave computer will not have an
effect on others. The experimental results show that the system could achieve a better distribution control
performances and solve the above problems.

Key words:  distributed control, RS-485, slave computer, AT89C51, KingView 6.55, upper computer