Research And Development Of Controlling System Of Greenhouse Environment Based On PLC

In china, a great agricultural country, the agriculture production plays a key role in nation al economy. In rencent years, the greenhouse industry grows rapidly, especially the small and middle scale cultivation in greenhouse with the continuing popularization of greenhouse plant ing technology. However, the modern application technology of facility agriculture develops s lowly, because a mountain of parameters such as huimidity, temperature, illumination and so on are still monitored manually with great labour and low effeciency.This paper focused on analyzing the greenhouse environment system characteristics an d control object, thus devising an operation system to control the greenhouse environment. It was based on the core of PLC equipped with digital humidity, temperature and illumination se nsor with high precision as a measuring instrument, which combined with configuration contr ol technology. It could conduct the real-time monitor, management and data analysis through human machine interfact with MCGS configuration software in order to overcome the manual shortcomings such as poor efficiency and high labour intensity. The main research task is as f ollowing:(1) Devising a general project on the basis of PLC environment-controlling system in gre enhouse.(2) Considering the total property of greenhouse controlling system parameters, it came up with a method to select components and devising hardware circuit.(3) Analyzing a programming methodology to collect data with manual and automatic m anagement through lower computer PLC.(4) Implementing the design method about human machine interface with upper compute r depended on MCGS configuration technology.(5) Conducting a software design about how to collect the real-time data about temperatu re and humidity, save previous data, make plots, revise upper and lower limits of temperature and humidity, set up alert parameters and modify online.(6) Designing a physical model by debugging between hardware parts and software part.(7) Conducting the experiment testing with debugging the integral machine.Taking debugging the integral system and experiment testing into consideration, it indicated that this environment-controlling system based on PLC ran reliably and operated convenie ntly, which duly promoted plant growth. Therefore, it had strong practical application and pop ularization value.