Remote monitoring system based on RFID technology
1 Introduction
At present, with the increasingly fierce market competition, various industries are working hard to improve work efficiency and save costs. In the field of remote monitoring, since traditional bar codes are artificially recognized at close range and can only identify one type of object, it is impossible to distinguish similar objects, and it is difficult to be destroyed due to rain, humidity, oily environment or handling. Identification, label loss is large, and the information provided is relatively small. Therefore, this paper proposes the introduction of RFID (Radio Frequency Identification) technology to establish a new remote monitoring system. The program has fast scanning, no contact, and anti-pollution. Loss, information and other characteristics.
2 Implementation of remote monitoring system
The system is mainly composed of monitoring and monitoring terminal, communication platform and monitoring center. The monitoring terminal is responsible for collecting various data and information required, and then connecting the collected data to the transparent data transmission terminal of the communication platform through the RS232 interface; the communication platform is a bridge between the monitoring terminal and the control center, and is mainly responsible for transparently transmitting the collected data. The data is transmitted without errors, in real time, and quickly. The embedded processor in the communication platform simply processes the monitoring data, and encapsulates the protocol and forwards it to the GPRS (General Packet Radio Service) module in the communication platform. It is sent by the GPRS network to the monitoring center; the monitoring center is responsible for analyzing and processing the data sent by the remote end, and saving the valid data to the database center. It can also issue commands to the remote monitoring terminal to perform parameter setting and call data in real time. The block diagram of the remote monitoring system is shown in Figure 1:
2.1 Monitoring terminal design
Compared with the use of bar code to collect and monitor target information, RFID electronic tags have the advantages of automatic scanning, no manual contact, strong anti-pollution ability (anti-dust, anti-smoke, anti-humidity), large amount of information, etc. RFID technology construction. A complete RFID system consists of three parts: a tag consists of a coupling element and a chip, each tag has a unique electronic code that is attached to the object to identify the target object; a Reader is a reader (sometimes also A device for writing) tag information; Antenna is an RF signal transmitted between a tag and a reader. The RFID system of the monitoring terminal selects 13.56M passive tag, 13.56M fixed passive reader and antenna with working frequency of 13.56MHz.
The process of monitoring the terminal work is: Reader sends 13.56MHz radio wave energy to Tag, drives Tag system to send internal data, Reader receives the interpretation data sequentially, and finally sends it to ARM (Advanced RISC Microprocessor, communication platform) via RS232 serial port. Advanced RISC microprocessors) do the corresponding processing. The principle of reading the tag data by the reader is: Reader transmits the 13.56M RF signal through the transmitting antenna, generates an induced current when the Tag enters the working area of ​​the transmitting antenna, and the Tag obtains energy is activated; the Tag and the Reader realize the RF through the coupling component The space of the signal is contactlessly coupled, and the energy transfer and data exchange are realized according to the timing relationship in the coupled channel; the Tag transmits the information such as its own code through the built-in transmitting antenna of the card; the receiving antenna of the system receives the carrier signal transmitted from the Tag, and The antenna adjuster is transmitted to the Reader, and the received signal is demodulated and decoded. Its principle block diagram is shown in Figure 2:
2.2 Communication platform design
The GPRS module of this communication platform selects WAVECOM Q2406 PL002, ARM selects SAMSUNG s3c2410AL-200902. The working principle of the communication platform is: After receiving the data collected by the monitoring terminal, ARM encapsulates and packages the data and then delivers it to the GPRS module. The GPRS and internet networks must be connected, and the GPRS network is responsible for sending the collected data to the monitoring center (because the network is sometimes unstable, the data is transparently transmitted in a transparent manner, and the short message is in the standby mode). At the same time, if the GPRS receives When the command is sent to the monitoring center, ARM is responsible for parsing the command and controlling the monitoring terminal to complete the command of the host computer.
2.3 Monitoring Center Design
The monitoring center consists of a PC with a public IP address and RFID reader software. The monitoring center background management software uses the self-developed RFID_Scanner software to implement parameter setting, establish network connection and data reception, storage, analysis and processing. Under the control of the program, the GPRS module can get a dynamic IP address after power-on, and it will actively send a connection request to the monitoring center server, so that the server can establish a Socket connection for it. The PPP server with a fixed address is bound by the AT command to perform handshake authentication and protocol configuration. After the PPP link is established, the TCP/IP protocol can be used to transmit and receive data between the monitoring center and the GPRS module. The monitoring center can query and observe in real time. And processing the data, sending the relevant command remote control terminal to complete the corresponding operation.
2.4 software program design
The main program flow is: First, the initialization operation, the initialization operation includes creating two threads (for monitoring data and processing data respectively), serial port initialization, sending and receiving short message initialization and GPRS data transparent transmission initialization; then the program enters an infinite loop state, constantly Monitor whether there is data arriving. If it is judged whether it is IP packet data or short message, it is IP packet data, it will call the sub-function receiving the IP packet data to receive the data; if it is short message, it will call the read short message sub-function to read the short message and save it to ARM. Delete the short message after the memory unit. If no data arrives, it is judged whether it is necessary to send short message or IP packet data. If it is necessary to send short message or IP packet data, the main function calls the corresponding sub-function to complete the data transmission; if not, return to the program. At the entrance to the infinite loop, continue to monitor if there is data arriving. The main function program code is as follows:
3 Conclusion
The remote monitoring system based on RFID technology has the characteristics of fast scanning, no contact, anti-oil pollution and large amount of information. Therefore, the system uses RFID technology to monitor the target, which provides a new application scheme for optimizing the remote monitoring system. There is a need in many areas to monitor targets in an efficient, low-cost manner. At present, the system has been put into the remote asset management. The actual application proves that the system is running well, and has achieved the expected design effect of high inventory efficiency, long-distance identification, strong adaptability to harsh environments, and more information. In the remote monitoring system, RFID technology replaces barcode recognition and monitoring target is the future development trend. In addition, the use of RFID technology to identify targets also has the characteristics of dynamic identification and accurate identification of individual objects, so it can further expand the application range of the system, in the future, the attendance of coal mine workers, cargo tracking in the logistics process, It will be extended to the real-time monitoring of special personnel such as medical institutions and prisons, commodity anti-counterfeiting, automatic highway toll collection, and drug and food safety management.
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