基于物联网的温室基质电导率实时监测系统开发

Electrical Conductivity (EC) of greenhouse substrate is a variety determined by many factors, which affect plant growth. Greenhouse substrate has specific structure and salinity, and greenhouse substrate EC could be easily used to evaluate the level of salinity. Hence, greenhouse substrate EC could be the evidence of nutrient management. In order to monitor greenhouse substrate EC, the Internet of Things was adopted in this system. The system consisted of one coordinator and several sensor nodes. The four-electrode method was introduced to measure the EC. A constant current source, generated by excitation source circuit, was inserted into soil by the lateral electrodes. And then the voltage between medial electrodes was detected and processed by the signal processing circuit. The result would be sent to the coordinator by ZigBee wireless module. MC55 GPRS module was added to the coordinator, connected by UART1 of JN5139. Data could be transmitted to the internet by GPRS. Then, server software was developed by C# to receive the data from GPRS. The function to observe data was also designed in the software. A test was conducted to the system. It shows that the system could collect, transmit and receive data stably. The system was suitable for long time monitoring.