Research On Instrument Network Based On Wireless Sensor Networks

Research on Instrument Network Based on Wireless Sensor NetworksThe definition of Instrument Network based on Wireless Sensor Network is thatdifferent instruments will be connected through the wireless sensor networktechnology in a certain region, and the measurement data will be transmitted to the PCBase Station in accordance with the protocols which is provided for the function ofwireless communication, and at last the PC Base Station upload the measurement datato the Remote Control Center by short messages; On the other hand, the RemoteControl Center sends a―upload request‖command to the PC Base Station through ashort message, and the instruments in the network are controlled and managed bywireless commands sent by the PC Base Station.Wireless communication is realized by the communication between the nodes ofcoordinator and router; Short message communication is achieved by the GSMmodule. The PC Base Station is divided into three parts, PC base stationadministration system, a coordinator node and a GSM module. The Control center isconsisted of the PC software for control center and a GSM module.The wireless communication protocol of the Instrument Network is the protocolof ZigBee conforming to the IEEE802.15.4standard. The model of this protocol is theOSI layered reference mode. It is the most popular in the application area with thebest prospects as a wireless communication protocol, due to it’s fully consideration ofthe requirements and the features of the Wireless Sensor Network. The Developmentof the protocol is a process from simple to complex through which three wirelesssensor network open source protocol stack: SimpliciTI, TIMAC and Z-stack whichare developed and provided by the Texas Instrument Company has been researchedand contrasted. As the result of that the basic methods of realization of ZigBeeprotocol and its application technology is mastered in this program. Finally, on thebasis of the research of the key modules of Z-stack protocol, two kinds of WSN nodesare designed: the coordinator and the router. The network in which measuring data aretransmitted in the form of wireless data is set up through the communication between the coordinator connected to the PC Base Station and router connected to theinstruments for measurement. And the intelligent measurement instrumentsmonitoring system is built up to achieve self-organized, multi hop and establish thefunction of routing network, providing solutions to the measuring data collection andfast uploading.The development of hardware is focused on the WSN node design. The CC2530system on chip is selected as the microprocessor to the node. In order to save cost andensure the reliability of radio frequency communication, using the ZigBee module ofDTK Electronics Company as a plug-and-play wireless module. The main chip of themodule is CC2530, and the module realized several functions such as the automaticnetworking, automatic network repairing, simple data transmission between any twonodes. At the same time, a circuit board for the module’s insert is designed to form acomplete functional WSN node. There are interfaces and slots for DEBUG, serial port,LCD, ZigBee module and the power supply for the hardware support. The serialcommunication between the RS232interface of the WSN node and the PC or theinstrument is realized by using MAX3232chip. Power management is designed byusing LM1117-3.3chip to convert the voltage to the regulator voltage values whichare alternative for220V, USB2.0-5V and dry batteries-3.3V as the three optionalpower supply mode. The circuit board is also equipped with power indicating,wireless and serial data transceiver indicating LED in variety of color in addition aswell as the components of keys for nodes’ tests conveniently. In the end, for thereason of isolation from electromagnetic interference of the external environment theWSN node is packaged in an aluminum box.The design of software is divided into two aspects: the embedded systemdevelopment of the nodes’ software and the software development of the PC basestation administration system and the Control Center. According to the instrumentserial communication protocol the embedded system of the WSN node is developedon the embedded development platform IAR for MCS-517.51A version using Clanguage. Several folders that is in accordance with the Z-stack protocol stackarchitecture are built corresponding to each layer, and the program files(including the main program file, the header files of the main program file, operating systeminterface document) in every folder is edited to achieve its function, therefore theoperating system hierarchical structure is established and the node’s function isrealized. The PC base station administration system is developed on the platform ofMicrosoft.NET, using SQL Server and ADO.NET to support the database technologyat the same time. The Control Center is built up by using Visual Basic language withthe database supported by Access. The function of sending and receiving sms isrealized by AT commands to control GSM module.Finally, the system is tested by using three kinds of software: Sensor Monitor,Packet Sniffer and SSCOM3.2. Sensor Monitor is software which developed by the TIcorporation to monitor and observe morphology of the wireless network for checkingthe count and the operation status of the nodes in the network. Packet Sniffer displaysthe format and content of the wireless data packet and observes the transceiver of thewireless data. SSCOM3.2verifies the normal serial communication operationbetween the node and PC. The designed test cases have covered all of the requiredfunctionality of the system, and the test result is good. After anglicizing themeasurement data of the instruments from the test, the result shows that this systemmeets the project test acceptance requirements.