关键词: 温室大棚, 温湿度, 监控系统, 可编程控制器

Abstract: Aiming at the problem that the domestic temperature and humidity monitoring system based on PLC can not combine the real‑time self‑adaptive adjustment with the wireless communication monitoring without distance limitation，a monitoring system based on PLC controller is designed，which can carry out the real‑time self‑adaptive adjustment of temperature and humidity and complete the wireless communication monitoring without distance limitation at the same time.We designed the system composition block diagram，introduced the system working process and mode，according to the design requirements selected the hardwares，according to the control quantity allocated the I/O address of the PLC，according to the working mode designed the ladder diagram program，according to the control object designed configuration interface，according to MODBUS RTU protocol，by 4G DTU wireless communication module and COMWAY server realized remote communication.The experiment was conducted in two environments of laboratory and greenhouse.The laboratory environment was relatively simple and stable，and the system response was faster；the greenhouse environment was relatively complex，and the system response was relatively slow，but in the controllable range. The results showed that the temperature and humidity monitoring system under the premise of ensuring the accuracy and reliability of the sensor，could perform the three main functions of temperature and humidity detection and display，temperature and humidity adaptive adjustment and remote monitoring without distance limitation and run correctly，and could achieve the expected goal in different environments.

Key words: Greenhouse, Temperature and humidity, Monitoring system, PLC