Study On Greenhouse Temperature Remote Measurement And Control System With Double CPU

It is very important to study the technology and method of temperature remote measurement and control in agriculture manufacture and science experiment. Temperature is a physical quantity to describe the cold-hot degree of an object, and is an important parameter in agriculture manufacture and science experiment. Many physical phenomena and chemical characteristics of an object are related to the temperature. For example, many manufacture processes must be realized in a range of temperature, to measure and control temperature is necessary and it is of great significance to social and economic benefits.Temperature monitoring and controlling is one of the most useful technologies in modern agriculture. In rural areas, almost each family has an outdoor small greenhouse in certain distance away from the main house. Thermometer is used to measure the temperature of the greenhouse. Since the thermometer can be only placed in the greenhouse and when the greenhouse is with dew, it is not easy to read the temperature data clearly and should to check the temperature so many times once in a while. It is harmful for the seedlings to be in the greenhouse with too hot or too cold environment. Therefore to research a temperature remote measurement and control system that can detect, display and alarm the temperature of the greenhouse far from the main house is an urgent demand in the modern agricultural manufacture.In this paper, the design processes and typical characteristics of a temperature remote measurement and control system have been presented. Comparing with other systems, the system has improvement of performance, achievement of remote control, reduction of cost and convenience of operation.Based on multilevel distributed structure and multi CPU, the temperature measurement and control system is composed with a host computer, a slave computer and an intense current controller. The slave computer, centered on ATmega16 Chip Microcomputer, has been used to collect the temperature data of greenhouse. The host computer connected to the slave computer with RS-485 interface is used to communicate with user through friendly interactive graphics and to comprehensively manage the greenhouse environmental data controlling, displaying and storing, and so on. The main specialties of the system are as follows: First, for a distributed structure is accepted in the system, the intensive monitoring and management mode can be achieved, especially for large-sized or connected greenhouses. As the slave computers of system are mutually independent, the system has many merits in flexibility and reliability. Second, since a 1-wire bus structure is adopted in the system, the slave computer system has advantages of flexibility, versatility, expandability, adaptability and maintainability. Third, many anti-interference technologies are used in software and hardware of the system, such as silvering shielding, software insulating, trapping and redundancy, the system is high reliable.The test results show that the software and hardware of the system can be normally operated in high reliability and expandability. The automatic control of greenhouse temperature can be achieved according to the requirement. The design objective of the system has been fulfilled.