Design And Implementation Of Distributed Remote Temperature And Humidity Monitoring System

The plant for aquatic product machining is a special place where the temperature and humidity of the environment is rigorous, and they must be controlled under appointed range. So the real-time monitor for this kinds of environments becomes a important problem which must be solved. Besides this, the refrigeration condition is also required in the transport, machining, storage and so on in order to keep the aquatic product fresh. So the real-time monitor of the temperature and humidity for the safe(<-18℃), freezer(<-38℃), flatter(<-38℃),fast-freeze room(<-20℃) and the machining room(12-16℃) become more and more important.Besides real-time monitor, the accommodation for the temperature and humidity is also important. The usual measure is realized by the air-condition which has refrigeration and radiativation function. When the environment temperature is higher than the initialization value, the refrigeration works, and the process is: the lower-temperature and lower- air pressure gas is firstly absorbed into the cylinder through compressor, become the high-temperature and higher-air pressure gas, pass the 4-way turning- valve, then turn into the high-are pressure and saturated gas which is cooled in the heat exchanger, at last, the gas is vented by the electronical-throttle and capillary. The process executes several times in order to lower the temperature. When the radiativation function is needed, the environment temperature is lower than the initialization value, the higher- temperature and higher- air pressure gas the compressor vented firstly pass heat exchanger, cool-down, exchange heat and make the environment temperature raise. Then the higher-air pressure gas which is cool-down inpour extraventricular machine to throttle and vaporize, at last the gas return back to the compressor and vented. The process excute several times in order to make the temperature raise. When the humidity needed to be accommodated, the usual way is to heat the water to product vapor. When the evaporator's surface temperature is lower than the dew point temperature of the air, the vapor becomes water. The request of the humidity is not a fixed value, but a range which is in the range of 30%-70%usualIy, and the most appropriate value is in the range of 40%-60%.In order to resolve this problems, the paper brings forward a system named distributing remote temperature and humidity monitor system based on the CAN bus. The system combine the computer technology, embed technology and the modern communication technology, it can realize the automatical management for the aquatic product plant. When the temperature or humidity beyond the limits, the system will give an alarm, and the LED will display at the same time, besides, the local parameter can be setup through the keyboard. There is also a computer on the CAN bus to compete the remote control for the system. When the environment request changed, the user can modify the setup-value, and download the plan to the node of the system in order to achieve the intelligent management.The system consists of an Up machine node and several intelligent nodes. Each node is connected by CAN bus. The intelligent node consists of control node and the local equipment and the control nodes include mini controller, CAN controller module, outside memory, serial interface and power supply. The local equipment includes several sensors and environment accommodatation equipment. The sensors include temperature- sensor, humidity-sensor, and the accommodatation is achieved by the environment equipment. This paper gives the design scheme as a whole and explains the key technology of the system design. The software and hardware realization of the intelligent nodes is introduced as an emphase and discuss the initialization in detail, the software realization of the CAN network, the detection of the sensor's signal, the software of the timer are discussed in details.The most outstanding merits of this project are:The CAN bus technology and the enhanced Single Chip Micyoco is used, the CAN bus provides an effective communication network for the system, the SCM provides a fast disposal ability.The scheme and the method to modify are flexible. The user can modify the scheme not only through the Up machine but also finish it locus in quo.The system uses the module method. The compatibility and the transplantablity are considered and reserve the empolder space. Then the system can be transplant to other system similarly flexibly. The system establishs the foundation for future digital, intelligent and network function.