Research of University Laboratory Equipment Remote Monitoring System Based on RFID and ZigBee

Research of University Laboratory Equipment Remote MonitoringSystem Based on RFID and ZigBee1SHEN Jun-tao, 1ZHANG Guo-qian, 1WEN Ding-yi 1College of Electronic and Information Engineering, HeBei University, BaoDing, Chinashenjuntaorxp@Keywords:RFID; ZigBee; Web Server; Gateway; Remote MonitoringAbstract. For the phenomenon of the college laboratory equipment mismanagement recent years, RFID/ZigBee-based laboratory equipment remote management solutions have been proposed. The hardware uses ZigBee wireless network chip, MSP430 low-power data processing chip and WiFi data transmission module as the core, combining with various sensor technology and RFID technology to perform information collection and transmission. The software is a web server developed in C # environment, using a three-tier structure to perform data storage, data access, and data processing. The experiments showed that it can perform communication between monitoring terminal and laboratory equipment timely and accurately, and achieve to integrate client, and improve the efficiency of managing the laboratory equipment to a certain extent.1 IntroductionLaboratory equipment is essential for colleges and universities, and shows an important sign of the overall strength of the school, charging with keeping creative ability and improving the quality education. With the progress of technology and the improvement of faculty, laboratory equipment is increasing. The traditional paper-based method has a significant lag, not only in operating and managing equipment, but also in personnel management. Although the rise of the 80’s RS-485 bus and CAN bus technology has solved the network, long-distance transmission, they have significant limits in power, wiring rules, communication capacity, etc. The iris and fingerprint identification technology of new technological revolution have shortcomings in storage capacity, recognition speed, long service life and price. In this paper, the self-organizing redundant network can be created within the scope of the laboratory through the ZigBee technology, which provides two-way wireless communications technology of low complexity, low power consumption, low cost, and high security. It solved the two problems to the source of energy and the exchange of non-contact card information through the combination of RFID radio frequency identification technology and IC technology, which can use radio waves to transfer information to make a quick identification, saving much workforce and improving work efficiency at the same time [1]. Integrating these technologies and powerful Internet technology can achieve remote monitoring of equipment.2 The architecture of managementThe remote monitoring system of laboratory equipment based on RFID and ZigBee is divided into three parts: network of laboratory equipment, gateway, as well as monitoring terminal part. The structure is shown in Figure 1.The laboratory equipment network is a wireless sensor network, which uses the ZigBee technology as the core, realizing data collection, transmission and enforcement of decisions. The monitoring terminal is based on a web server, which monitors and controls the laboratory through connecting the Gateway and stores the monitor data in the database, then develop a rational control decision according to the information of database storage [2]. The gateway is responsible for the transmission of the information flow from the laboratory equipment Network to the Internet monitoring terminal, realizing communicating between two different networks by protocolchangeover. The server judges the type and meaning of the information collected to control the sending direction. When a device failed, the server could make a timely processing or alarm information to the monitoring terminal. The monitor terminal designed an intuitive monitoring interface which can keep abreast of the equipment for the staff to make a rational decision. At the same time, users can also use terminal to reserve a device by accessing to the server. Following the data transmission, the software architecture of the equipment management can be divided into four levels: data acquisition, data transmission, data storage, and data access.Fig.1The overall structure of the system3 Role of each moduleSpecific works of each module are as follows:3.1 With a network of laboratory equipment achieve data acquisition and executive decision-makingThe laboratory equipment network is a wireless sensor network based on ZigBee2007 protocol, which can collect current, voltage, temperature, status information and make an action by configuring terminal nodes on each device. The hardware circuit of the terminal node is made up of microcontroller CC2530, A/D converter, RFID receiver MFRC522 and anti-jamming circuit. The structure is shown in Figure 2.Fig.2 The structure of terminal nodeCC2530 set in the enhanced 8051 CPU, combined with the excellent performance of the leading RF transceiver, and built-in 8-KB RAM, an 8-channel 12-bit A/D converter, sleep timer and other functions, ensures to build a strong network node with low total cost of materials. MFRC522, integrated modem circuit, is a non-contact card reader module, and can be connected to the antenna driver stage using a few external components, ensuring the accuracy and reliability of the data transmission, and simplifying the PCB design. The terminal node uses CC2530 as the core, whichuse the temperature sensor, the current sensor, the voltage sensor to get working parameters, and collect the user's identity information through the RFID receiver, which is converted to the digital signal microcontroller can process. These data are processed by CC2530 and converted into radio waves to be sent from the RF circuit. At the same time, the terminal switches output role in open or closed according to the monitoring terminal information for decision-making.3.2 With gateway achieve data transmissionGateway is only one of each wireless sensor network and placed in the WiFi signal coverage area, connecting the ZigBee network and the Internet. The hardware includes: Microprocessor MSP430F149, ZigBee chip CC2530, WIFI module MT-MW-08S, etc. The structure is shown in Figure 3.Fig.3 The structure of gatewayMSP430F149 has the architecture of 16 RISC, and its high-speed computing power can reach 125ns. Five low power modes can be achieved by switching the three oscillators [3]. In addition there are many registers, and wealth of internal modules in its internal. All these features make up the insufficiency of the wireless module in data processing. ZigBee works as the coordinator node of the laboratory equipment network, for organization, management and other works of the network. The WiFi module with the transparent serial transmission doesn’t need the AT commands, which can connect to the Internet by configuring serial port baud rate, network transmission type, local and remote port number and other parameters on the web, greatly reducing the workload of the protocol changeover of the gateway. SD card is used for data cache to avoid loss data when the data transmission is not synchronous or power-down and failure.3.3 With monitoring terminal achieve data storage and access decision-makingThe network server located the end of remote monitoring decisions is a subsystem of web-based data management and application, and a windows service program writes in platform of C# . The design of web server mainly includes front-end interface, back-end database and the communication between Server and gateway.The system uses dynamic web technology to write the front-end interface program under B/S mode for accessing to database information dynamically, operating the database, alarming when exceeding the set value. The database is designed with SQL Server 2000, using technology which supports for disconnected access to the database, greatly reducing the workload of the server-side. Managing on the database through SQL statements can achieve to display, monitor, add and delete the information in real time. The system communicates with the gateway in C/S mode for data transmission, which can complete the equipment management of different parts and improve the ability of management and expand the scope of management [4].Based on collecting accurate, real-time information, the data for further processing can form graphics, reports, curves, and other visual contents for the administrators and users to refer to make more accurate, faster decision-making, while reducing the time and effort in the colleges and universities in data collection, processing, maintenance and other activities, and greatly improving the efficiency in the use of laboratory equipment.4 The design of software4.1 Identification subroutineRadio frequency identification for identification includes information collection, information processing, information storage and feedback.The information acquisition is achieved through the RFID receiver on the terminal. Each user has the only one radio frequency identification card with its status. Because the receiver sends specific frequency radio waves, when the card close to the receiver to a certain distance, it can be driven to carry out detecting cards, anti-collision, authentication password, and finally sent the letter stored in the chip under the induced current [5].Information processing, storage and feedback are performed by the server. The server parses raw RFID data to extract meaningful business logic data (device address and a unique identification number), and verify the user's identity by querying the reservation information in the database. If the validation is successful, the server return a corresponding control command of which device is turned on and start timing, meanwhile these records are stored in the database. Otherwise, issue a warning.4.2 Data transfer subroutineThe gateway transmits data by converting network protocol which consists of two parts: ①the conversion of the ZigBee protocol to the TCP protocol. The microprocessor can parse the data of ZigBee network and extract useful information. Because the WiFi module set in wireless networking protocol and TCP/IP protocol, the data can be repackaged into IP packets and sent to the Internet after encoded and modulated to be RF signal [6]. ② The conversion of TCP protocol to the ZigBee protocol. When the IP data packets are sent to the laboratory equipment network, it has to make the appropriate conversion.The system adopted interrupt mode of MSP430 and clever used the receiving priority of interrupt vectors (UART0 >UART1) in data reception. When the receiving interrupts of the two serial ports occur simultaneously, that of UART0 can be carried out preferentially, so the device can be responsive to the commands from the monitoring terminal for the first time. Noting the interrupt nesting of MSP430 is disabled by default, the master interrupt, EINT, should be enabled in the interrupt routine again, or even an arrival of interrupt of a higher priority event, the system would not respond. The workflow of MSP430 is shown in Figure 4.Fig.4 The workflow of MSP4304.3 Information management subroutineInformation management uses three-tier architecture: presentation layer, business logic layer and data access layer.The presentation layer is a front desk man-machine interface including the interface of administrators and users, which mainly is used to input commands and show operating parameters of equipment and query book record on the client. If the client authentication is successful, the information would be converted into a certain format and then sent to the supervisor terminal which extracts this information and shows it in the form of the web page. The intermediate layer receives the request of client's connection and verifies their identity. If legitimate, handle customers' request event, such as executing logic judgment and operating the database, and the results would be returned to the client or laboratory equipment network. At the same time, it can keep server security, and resist illegal network to intrude. The data layer, allocated on the database server side, performs to query, modify, update to the database by processing data logic and accepting the request of the network server for the database. Then the results will be returned to the server [7]. The server structure is shown in Figure 5.Fig.5 The web server architecture5 The self-organization and self-healing of laboratory equipment networkZigBee Alliance has redefined the wireless sensor network based on the 802.15.4 standard. Its structure from top to bottom is followed by the application layer, network layer (NWK), media access control layer (MAC) and physical layer (PHY). The NWK layer is the core of the ZigBee network, and the strong network layer protocol ensures the self- organizing and self-healing of ZigBee network.A network of laboratory equipment can be created through ZigBee network self-organization. The coordinator selects a suitable channel for communication through scanning the energy detection (ED), and creates a new PAN ID. The PAN can be started after selecting the network address of the coordinator. Routing Nodes and End Nodes try to associate through passive scanning, and select an appropriate coordinator to associate according the results of scanning channel. The coordinator makes decisions which include associating device, assigning a short address, deleting the device information in a particular period by judging the PAN resources currently. Each device in the network dynamically is assigned a unique 16-bit network address using the mechanism of distributed network address allocation to realize device identification, data transmission, data packet routing, and other functions [8].The characteristic of self-healing can identify the joining, leaving, moving of a device, and repair the network. The coordinator broadcasts Hello beacon frame to the network at regular time intervals, identifying the number and use of the devices in the network by returning acknowledgment frames of each node, and reflects the changes of network structure and working conditions of the nodes to the monitoring terminal in a timely manner. The server determines whether the operation is legal through self-identification, in order to develop proper decision-making, such as updating database information or alarming. When communication between anequipment and network cannot be successful due to a link failure in the network, the uplink device starts routing healing abilities to find a new path for data transmission.The features of self-organizing, self-healing ensure the stable and fast data transmission, and the entire process is achieved by the network primitives without human intervention. The critical network primitives: NLME-SCAN. request、NLME-SET. request、NLME-ASSOCIATE. request. The data processing flow of ZigBee network is shown in Figure 6.Fig.6 The data processing flow of ZigBee network6 The experimental resultsThe system built a small laboratory equipment network with 20 terminal nodes, which were placed in 20 different devices, and 10 routing nodes, which were allocated within the scope of the terminal nodes’ signal, in the laboratory of C2 floor. The terminal nodes regularly sent data to the appropriate routing nodes, and then went to sleep after completing the transmission. The data were sent by the routing nodes to the gateway which transferred the data to the server.The experimental results show: ①Users could access server on any PC connected to the Internet to query the usage of devices and make appointments. Administrators could log to monitor the devices and control them on or off by sending commands. ②Setting the coordinator node send data to the microprocessor of the gateway continuously, the control information from the monitoring terminal was still able to turn the devices on or off due to high interrupt priority. ③When setting time interval of the data acquisition 10 seconds, the data transmission delay was about 1-3 seconds. When increasing the number of the device terminals or the frequency of the data acquisition, transmission delay increased because of the increasing of the data traffic in the ZigBee network. When a routing node of key position was removed, there would be packet loss. So the routing nodes should be distributed reasonably, and the balance between data traffic and network delay is necessary.7 ConclusionsIn this paper, the design method of hardware and software of laboratory equipment management system based on RFID/ZigBee was put forward，and the self-organization, self-healing capabilities of the ZigBee network were introduced. The system set up a mesh topology network for laboratory equipment, and initially realized the remote switch operation to the equipment, and could identify simple data types through the web server. Laboratory equipment management system, which set network, control, automation in one, was constructed, and there will be certain significance for college laboratory equipment management.REFERENCES[1] Ying J. The Research and Design of Non-contact IC Card [D]. Shanghai: Shanghai Institute ofMetallurgy (SIM), 2000:8-19.[2] Xiaojun Z, Haixia S, Mingwei R. Remote Monitor and Control System Based on ARM9 andCAN Bus [J]. 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