The Reasearch And Design Of Multi Channel Temperature Measurement System Of The Greenhouse

Temperature is an important factor to ensure good growth of the crop. As a large agricultural country, greenhouses are widely used in the cultivation process to plant greenhouse vegetables. Good temperature control of greenhouses can increase the yield of vegetables in certain extant, so the Real-time observation of temperature inside the greenhouse is particularly important. Temperature is an important commonly measured and charged parameters in the greenhouse. The traditional method of measurement using conventional thermometer and control manually is complex and cumbersome. The MCU-based on embedded real-time measurement technology, which integrate computer technology and measurement technology, brings fundamental changes to traditional measurement methods and means. Embedded measurement system with a microcontroller core replacing conventional measurement method, which using traditional instruments and meters, can easily realize a measurement with process of automation, measurement result of digitalization and instrumentation functional of diversification, and can play a very important role in the measurement of greenhouse accuracy and reducing labor intensity of staff operations. According to actual needs, this topic designed a multi-point temperature measurement system based microcontroller and digital single-bus technology.The system is composed by the host computers and the slave computer. The slave computer, which is composed of temperatures collected circuit, clock circuit, display circuit, RS485 interface circuit and so forth, is an embedded measurement unit with microcontroller as a core. The slave computer is responsible for collecting temperature data and sending it to the host computer. The host computer is mainly composed of PC installing the software of data acquisition and management. We develop the host computer Software using LabVIEW.LabVIEW is a graphical programming environment, with the characteristic of intuitive, easy to learn and stronger development function. The software developed using LabVIEW is highly reusable and can easily connect with third-party software. We can take advantage of a powerful computer, data processing and transmission capacity using the LabVIEW software development. The host computer mainly achieves the task of data display, alarm, storage and query. The acquisition and management software of the host computer is divided into two parts, the first part is the design of the front panel procedure, and the second part is the design of the back panel diagram procedure. This temperature control system whose stabilization and maintainability is good doesn't need any fixed network to support and is easily installed.The system can measure real-time temperature inside the greenhouse. The measurement results not only can be shown in the slave computer, but also can be transmitted to the host computer through RS-485 bus for further processing. When the temperature exceeds a pre-set upper and lower limit, the system will start the alarm module alarm, greenhouse managers in accordance with warnings to take certain measures to control the temperature inside the greenhouse. In this paper, the system's hardware implementation and software implementation process has been discussed in detail. The paper focused on analysis of the device selection of the main hardware circuits, circuit design and the process of design and development of slave computer's critical software and host computer software. The paper gives the slave computer principle block diagram, the slave computer electrical circuit board diagram, RS232/485 converter principle circuit diagram, RS232/485 converter circuit board, and gives the temperature data acquisition and memory interface and the recorded data playback interface of the host computer data acquisition and management software.