Research And Application In Multi-parameter Of Greenhouse Environment Computer Control System

With the popularization of greenhouse technology, the amount of greenhouse is larger and larger, However, the control of greenhouse is becoming a difficult problem. Currently, the control system of greenhouse is mostly using a transfers system which consists of analog sensors, multiplexing analog switches, A/D conversion units and SCM. This kind of collection system needs a lot of cables which is laid to make the signal of the sensor be sent to the collection card in the greenhouse. Thus the work of fixing and take-down is miscellaneous, and the cost is high. What's more, what is transferred in the system is analog signals which are easily interfered and have more ullage. It is hard for the controller to make a decision in time according to the change because the measure error is bigger. So under this circumstance, it is necessary to develop a real time and precise control system which is in a position to deal with information of many nods.This paper gives a greenhouse temperature control project which is based upon the SCM and digital monobus technology. In this project, the change of temperature in the greenhouse is transformed into the change of electric current and then into the change of voltage by using the temperature sensors. The change of voltage is input into the A/D conversion units and the result is dealt with by SCM. At last the real time temperature in the greenhouse is displayed on the monitor under the control of SCM. Once the value of the temperature in the greenhouse exceeds the minimum and maximum which is pre-established, the SCM will give an alarm and autocontrol the temperature in the greenhouse. This project can make real time patrol checking to the different nod's temperature in the greenhouse, and every separate checking unit can finish its task independently. At the same time, very separate checking unit can make timing collection according to the instruction from the main control, and the measure results can not only be displayed at home but also can be further processed and be kept in the archives by using the SCM's serial interface and RS-485 bus and communication protocols. This temperature control system whose stabilization and maintainability is good doesn't need any fixed network to support and is easily fixed.