## 3 Results and Discussions  
### Growing Environment Measurement by the WSN  
#### 3.1.1 Growing Environment Data Acquired by the WSN  
The new WSN system with the selected weather station (WS700-UMB, Lufft Inc., Berlin, Germany) and TDR type soil water potential sensors (WD-3-WET-SE, ARP Co., Ltd.) were designed and deployed in the vineyard. The weather station can acquire air temperature, relative humidity, air pressure, wind speed, wind direction, 1 min precipitation and solar irradiance data, while the soil water potential sensor can acquire the soil volumetric water content, soil temperature and soil electrical conductivity. These data are collected by gateway via 920 MHz radio and sent to the data link server that is connected to the gateway (Figure 7). To send these acquired data to the cloud sensor infrastructure, the data link server uses HTTP-GET API defined by the cloud sensor infrastructure. In the revised WSN system, we use the SPPNet protocol produced by Sumitomo Precision Products Co., Ltd. The weather station is connected to the sensor node (SP-0030) by a two-wire RS485 network. Connecting the node to the RS485 serial interface devices can make a 1 to 1 or 1 to \(N\) see Duplex wireless communication system. The power source is the AC 100 V commercial power supply existing in the vineyard which is converted to DC 24 V. On the other hand, each soil moisture sensor is connected to the analog sensor node (SP-0020) with specifications similar to those of the weather station. Its electricity source is DC from a solar panel deployed above the soil moisture sensor. These sensor nodes were developed in this study in order to connect the sensor to this WSN system (Table 1). The data link server of this WSN system has a customized web application based on SPP's commercial product 'EcoWizard' which has HTTP Server capability, DB and Flash Application. Figure 7: Structure of the WSN in Tomi-no-oka vineyard: (**a**) Installation points of sensors; (**b**) System configuration of WSN. Regarding the data communication, the Modbus protocol is applied and the frequency of the radio used in this WSN system is a 920 MHz radio wave based on the Wireless Smart Utility Network which enables long-range wireless communication. Thanks to the 920 MHz, wave attenuation caused by the plant is not significant compared to the 2.4 GHz used in the previous WSN. In addition, this SPPNet protocol can provide the wireless transmission system of sensors compatible with Modbus protocol easier than in the eKo sensor network. All environmental data collected by the sensors in the WSN are sent to the Modbus master (Gateway GW-Z01), then stored in the data link server. The Over-The-Air throughput of this network is more than 100 kbps in the ideal state, while the actual throughput is more than 24 kbps. The MAC of this network is CSMA/CA system and comply with the transmission time restrictions defined in Association of Radio Industries and Business in Japan (ARIB) STD-T108. The routing protocol of this system ad-hoc mesh networking protocol, self-organizing and self-healing. In addition, Transmission latency of this system is from 2 to 912 ms/hop. Other information about this system is shown in Figure 8.  
This WSN consists of a weather station and three soil moisture sensors and a soil water potential sensor (Table 2, Figure 9). The soil water potential sensor was manufactured for this study to translate the soil water content into a voltage variation, and composed of a gypsum block and simple electric  
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Figure 8: The information about SPPNet protocol used in this study. circuit to reduce material costs. As a result, it costs only about 5000 yen to produce this sensor and the process is so simple that farmers can do it by themselves. As the sensor for measuring the other soil information, the WD3-WET-SE soil moisture sensor was selected. It can measure the soil volumetric moisture content, soil electric conductivity and soil temperature at the same time.