Design on remote monitoring and control system for greenhouse group based on ZigBee and internet

Wireless technologies have developed rapidly in recent years. Types of wireless technologies range from IrDA that uses infrared light for short-range, point-to-point communications, to wireless personal area network for short range, point-to multi-point communications, such as Bluetooth and ZigBee, to mid-range, multi-hop wireless local area network, to long-distance cellular phone systems, such as GSM/GPRS and CDMA. In this paper, focusing on the domestic research of intelligent control system for greenhouse group and the greenhouse construction of Heilongjiang province, a new type remote monitoring and control system for greenhouse group based on ZigBee and Internet was developed. The group control system was composed of some separate monitoring systems. The data of the separate monitoring servers were sent to master server and connected to remote administration system with master server. The sensor network of the separate monitoring system was based on ZigBee nodes. The monitor nodes were composed by two parts: The communication module and sensor module. The MCU of the communication module was adopted CC2530 of Texas Instruments. The flash memory, which is important to application used was much bigger than the last generation. This character had an advantage in ZigBee Pro / 2007 protocol stack, which was complex and multi-function used. The CC2520, RF module, was also built-in it. This enhanced the capacity of the RF function of the CC2530.The maximum RF output power is 4.5 dBm. The power cost of the chip was very low, this character was quite benefit for the application used in field monitoring. The sensor part was composed by air temperature humidity sensor SHT11 which was made from Sensirion company and silicon solar cell BPW34S which was made from Siemens company. The SHT11 sensor was low-power cost, 12-bit temperature output and 14-bit humidity output, 2-wire serial port. The MCU read the temperature and humidity data through the 2-wire serial port. The silicon solar cell output voltage from 10mv to 1.1V. The operational amplifier TLV2372 amplified the voltage for 3 times, then output for the analog-digital converter of the MCU. In order to save more power of battery, the sensors would sleep until be next waked by the MCU after the MCU complete read the data. The sensor data collected by the ZigBee coordinator were sent to a router by a protocol converter of RS232-RJ45. The PDA and wireless IP camera were also used in the system. The data of them were also sent to the router. The router sent all the data to monitor server. The software design was based on the theory of large system. It had the functions such as: real-time video monitoring, real-time data curve display, historical reports, alarm, remote distribution, database management and decision module based on historical data. The whole system was tested in sunlight greenhouses of Northeast Agricultural University. The packet loss rate of two nodes was also tested in different distance of 0.12, 0.5, 10, 20, 35, 52, 70 and 80 m.The result showed that in the close-up range(less than 20 m), the packet loss rate was very low, less than 0.5%. In middle distance (20~50 m), due to the irregularity of low-power communication links, the packet loss rate increased firstly and then decreased. In long distance (more than 50 m), the wireless signal intensity decreased, the packet loss rate increased sharply. According to the whole test in the greenhouse, the monitor system worked stably. The design meets the requirement of the application in engineering