Design of distributed temperature and humidity monitoring system based on single-chip microcomputer

With the continuous development of electronic technology, large-scale centralized control technology has also been greatly improved, the traditional RS485 bus technology, in the equipment network performance, a bus can be hooked up to 32 node equipment, to a large extent, to meet a number of warehouses or monitoring stations of the centralized control requirements. However, because the longest transmission distance of the RS485 bus can reach 1200 meters, even after the relay can not transmit a few kilometers distance, it is difficult to meet the requirements of more remote monitoring and control. At present, Ethernet communication has been widely used in life and production, Ethernet wiring is also very extensive, so the Ethernet communication mode instead of RS485 bus transmission mode is more conducive to the realization of a wide range of remote distributed network system. In this paper, for temperature and humidity monitoring system, with the characteristics of Ethernet without rewiring and convenient installation, a distributed temperature and humidity monitoring system based on Ethernet is developed, and the single chip computer is used to collect nodes, and the temperature and humidity monitoring system is completed by the design of the minimum system, the design of temperature and humidity collection circuit, A/D conversion circuit, Then through the RS485 bus will have a separate address of the unit temperature and humidity monitoring system connected to a bus, through a RS485 to TCP/IP protocol converter can realize single-chip Ethernet communication, greenhouse data transmission to the PC, remote monitoring function.