Greenhouse Environment Control Device Design Based On Programmable Logic Controller (PLC)

Greenhouse is a kind of high efficient and intensive facility for agricultural production, which can adjust the microclimate for crops to obtain anti-seasonal production and improve the quality and efficiency.Programmable Logic Controller (PLC) is a new type of universal and automatic control device, which combined the control technology of the traditional relay, computer technology and communication technology together. It had the advantages of easy programming, good expansibility and high reliability, which was suitable for long-term continuous operation. Moreover, it was very suitable for the control requirements of efficient greenhouse.The research designed a kind of monitoring system based on the greenhouse environment of PLC. It can realize the acquisition and control of the greenhouse temperature, humidity, solar radiation intensity, wind speed and so on. The hardware of the control system mainly consists of hw-36MT-3DA PLC, wireless RF modules, switching power and various monitoring sensors of greenhouse environment from Haiwei Automation Company, which is used to check the greenhouse temperature, humidity, wind speed and other parameters inside. Greenhouse software includes monitoring software of host computer and user software of slave computer. The computer monitoring, through the RS232serial port and PLC communication, the way of which uses RF wireless transmission mode, realizes remote monitoring, displays and queries real-time and historical data. Development environment of Computer software uses hwStar V5.02programming software developed by Haiwei Automation Company.After being put into greenhouse operation in the College of Engineering of Nanjing Agricultural University, the system has achieved a very good effect on the collection of each environmental factor inside, and has the advantages of simple operation, stable and reliable working characteristics.