| Based on the analysis of the control characteristics of agricultural greenhouse and requirements of the main parameters ,PLC is used to achieve controlling method of the main parameters in greenhouse in this paper, this method could effectively control the greenhouse temperature, humidity, light intensity, CO2 concentration simultaneously.Taking cucumber cultivation in small and medium agricultural greenhouse as an example, this paper presented control system which used PLC as a core, the system was consisted of three parts ,including information collection system, intelligent control unit and executive body, the information collection system used FX2N-8AD analog module to accomplish the environmental parameters'collection and input; compared the values of sensor detections with greenhouse's parameter, master control unit FX2-32MT outputted corresponding control signal; according to the control signal, executive body drove motors , solenoid valves, fans and other equipments to achieve the intelligent control of greenhouse. GX-Simulator simulation software tests showed that the control system could be adjusted easily relative environmental parameters which are based on the different periods of control requirements.In the light of climatic conditions for a particular region, this paper studied computer monitoring system in greenhouse which used PLC as a core, The main feature of the system is: in the first place, PLC has a simple interface circuit and less external components, the system ensured the control requirements of greenhouse since it was reliable; Secondly, the system used the control method of five-paragraph changing temperature, in other words, the system set up special optimum temperature in different period to make use of maximum natural resources; Finally, according to the difference time and the different importance of environmental factors, the system set up different priorities slots in each time, so it could ensure high quality development of crops. |
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