GPRS Remote Wireless Data Acquisition and monitoring system

　　1、 Introduction

　　With the development of communication technology, especially the rise of wireless communication technology, it has greatly enriched the life of modern urban residents. Modern urban residential buildings and high-rise buildings are widely popularized, and the pace of urban life is accelerated. In the past, there were some problems in the way of manual door-to-door meter reading, such as low meter reading efficiency and slow cost recovery, which can no longer adapt to the development of modern society. Nowadays, the public telephone network, public Internet and GSM wireless network have basically covered most parts of the country. The efficient computer management, the support of large-capacity database system and the globalization of communication carrier make the traditional way of door-to-door meter reading move forward to networking and informatization. The meter reading and payment method of urban networking has become a new trend.

　　For gas companies, the gas consumption of large users (including industrial production, public services, heating and refrigeration enterprises, group users, etc.) is relatively large, accounting for a considerable proportion in the gas sales of the whole gas company, and the proportion is still expanding. The gas consumption and recovery of these public users will directly affect the operating efficiency of the company.

　　How to grasp the gas consumption of these large users at any time and monitor the operation status of their gas flow meters and gas equipment, especially large-scale gas equipment in real time is a very important and complex problem for gas companies.

　　A GPRS Remote Wireless Data Acquisition and monitoring system for gas flowmeter / gas equipment for public service users is established for the development and transformation of large users of gas flowmeter of gas group, as well as user charge management, information acquisition, data analysis and customer service, The system uses the data transmission function of GSM wireless public network (GPRS wireless network mode) to realize the long-distance wireless transmission of various data on the industrial site. It overcomes the shortcomings of the original networking mode, such as short communication distance, unstable performance, complex network maintenance and high cost. It can realize no dead zone coverage in ordinary occasions and no distance limit. It has the following characteristics:

　　① Timely understand the operation status of gas flowmeter / gas equipment, find out possible hidden dangers through the analysis of these data, improve the management level of metering equipment and reduce the difference between supply and marketing;

　　② Timely understand the gas consumption parameters of a single user, including gas pressure, heat load, instantaneous flow, cumulative flow, etc., not only master the gas consumption characteristics of the user and reasonably allocate gas resources, but also master the user's gas consumption at any time to avoid arrears;

　　③ Through timely and accurate analysis of the gas consumption of all public service users, provide basic data for the reasonable analysis, supply and allocation of the whole gas pipeline network; This is also an effective means to improve the company's service quality to key customers.

　　GPRS Remote Wireless Data Acquisition and monitoring system has many functions, such as user management, instrument management, collector management, data query and analysis, alarm prompt and so on.

　　The system makes full use of the characteristics of wide distribution and safe and stable operation of public mobile network, and adopts industrial GPRS module to realize data encryption transmission. The difficulty of development is to master GPRS data transmission format, data encryption technology, APN access and tunnel connection, explosion-proof product design, etc.

　　2、 Selection of data acquisition mode of the system

　　According to the existing technology and application, the following transmission technologies are available:

　　Wireless mode (cluster data transmission technology or GPRS data transmission technology); DDN dedicated line, X.25 or frame delay technology; PSTN (China public telephone network) technology; All the above transmission methods have their own advantages and disadvantages: the cluster data transmission technology must be supported by a special cluster system and need to apply for a special frequency point. The system investment is large and the communication speed is slow; The transmission speed of DDN dedicated line, X.25 or frame delay technology is fast, but the coverage area is limited and the operation cost is high. When the amount of data is not large, it is a little overqualified;

　　PSTN telephone dialing method covers a wide area, with less investment, low operation cost, simplicity, convenience, stability and reliability, and the speed is slightly slow, but it can fully meet the requirements in the case of a small amount of data.

　　GPRS communication mode has the characteristics of real-time online, billing by volume, fast login, high-speed transmission, wide coverage, no need to apply for frequency occupation, no need to set up a special antenna and so on. It is an ideal remote wireless communication mode at present.

　　GSM covers a wider area than the cluster mode, which can make effective use of rare wireless resources, has flexible billing methods (data volume or duration), can quickly establish access, and can also use IP protocol to connect to the external data network. The service cost of GPRS is only one tenth of the cost of CSD (circuit switched data), that is, dial-up data service.

　　By comprehensively comparing the advantages and disadvantages of the above transmission modes, the system adopts GPRS to realize remote wireless data acquisition and monitoring.

　　3、 Composition and working process of GPRS Remote Wireless Data Acquisition and monitoring system

　　GPRS Remote Wireless Data Acquisition and monitoring system is composed of field instrument, GPRS data collector and upper computer monitoring and management system:

　　1. Field instrument

　　The field instrument is equipped with RS485 communication interface, which is mainly used to measure and display the user's consumption, and transmit the consumption information, status information and abnormal information to the GPRS industrial meter data acquisition transmitter.

　　2. GPRS industrial meter data acquisition transmitter

　　GPRS industrial meter data acquisition transmitter is manufactured by using advanced micro power consumption large-scale integrated circuit, industrial GPRS module and advanced surface mount technology. It integrates the functions of remote reading, remote control, status alarm and anti-theft. It can be widely used in the measurement and control of industrial instruments.

　　GPRS industrial meter data acquisition transmitter can be set to automatic valve closing and passive valve closing. Automatic valve closing is to close the valve immediately after the meter has abnormal conditions (such as undervoltage and magnetic interference). Passive valve closing means that the on-site measuring instrument only receives the correct valve closing command from the management system to execute the valve closing operation. The sales management software of the management department can analyze various data of industrial tables and generate various statistical analysis reports, which truly realizes the automation of remote control management.

　　GPRS wireless remote data collector can collect the accumulated flow of the attached instrument once every hour, and actively transmit the data of the attached instrument to the monitoring and management system at regular intervals every day. In case of abnormal conditions (such as power failure of external power supply), the data collector will actively transmit alarm information to the monitoring and management system to prompt timely maintenance. GPRS wireless remote data collector can set the number and model of attached instruments by the monitoring and management system, and the monitoring and management system can read the current state of the data collector at any time, such as the internal time of the data collector, the number of attached meters, instrument type and other information.

　　3. Monitoring center setting and network database server host

　　Select the IBM as / 400 minicomputer as the host of the network database server. The system itself is equipped with operating system (os400), database (udbfor AS400), security system, network management system, communication and performance monitoring system and office software (louts domain for AS400).

　　The web server of the group monitoring and management center is installed with Windows 2000 (Chinese version) and msiis (web server), which mainly meets the remote data query function.

　　The monitoring center builds an Internet network with fixed IP address, which is mainly composed of router, firewall, proxy server, monitoring console, query console, database server and corresponding monitoring software, query software and database management program.

　　GPRS Remote Wireless Data Acquisition and monitoring system takes the head office as the center, all data information is saved in the central database, and the data required by business offices, communities and mobile operating devices are obtained through the center. Based on the head office server as the core, complete the data communication between the head office, business office, community, mobile operating device and meter. The advantages of this method are centralized data management, reducing daily operation and maintenance costs, and enabling the operation of business offices and communities to be effectively managed and monitored.

　　The GPRS module is connected to the GPRS network through dial-up. The fixed IP address and communication port number of the monitoring center are set in the GPRS module. The GPRS module finds the TCP / IP server of the monitoring center through the IP address and port number and sends a connection request to the monitoring software. After receiving the connection request, the monitoring software verifies its communication address and establishes the corresponding communication connection after passing the verification, Each monitoring terminal completes the communication connection with the monitoring center in turn. The system communication can be divided into two ways: the monitoring center calls and tests the monitoring terminal and the terminal actively reports. Each monitoring terminal has its own communication connection with the monitoring center, which does not interfere with each other, and can realize one by one communication or group measurement and group control.

　　The management system of the monitoring center adopts modular design, which is divided into data communication module, data verification module, data storage module, query and statistics module, report printing module, database backup module, etc. It can realize the functions of user information management, meter information management, payment information management, user meter communication, user information query, meter information query, payment information query, sending and receiving information query, abnormal information query, warranty information query, period consumption analysis curve, SIM card management, automatic transmission setting, business statistics and print data backup, data recovery and so on.

　　4. Working process

　　When GPRS industrial meter data acquisition transmitter is used, connect the industrial gas meter to be collected and transmitted with the corresponding acquisition transmitter according to certain rules, the membrane meter is connected with the acquisition transmitter with pulse counting interface, and the intelligent meter with RS485 interface is connected with the acquisition transmitter with 485 interface. If there is a valve, connect the valve control line with the acquisition transmitter. Then open an account in the computer database management system of the management department, the computer enters the user information, and sends the initialization command to the acquisition transmitter for corresponding initialization operation. When the acquisition transmitter returns the correct information, it indicates that other operations can be carried out. Through the computer database management system, the gas company can remotely read and remotely control the user's on-site metering instrument with GPRS industrial meter data acquisition transmitter in real time or time, so as to realize real-time or regular reading of meter information, control of on-off valve, exception handling and other operations. The gas company prompts the user to pay according to the monthly meter reading data. The maintenance personnel need the authorization of the computer system during on-site maintenance. The authorized mobile phone or handheld device can check the meter, read the meter and operate the on-off valve of the designated collection transmitter on-site metering instrument within the authorized time (generally 8 hours). After external power failure, the acquisition transmitter can still work for more than 24 - 36 hours, record various abnormal reports, and regularly send the meter undervoltage status to the management system. After the power supply is restored, it will automatically stop sending undervoltage information. In case of magnetic interference and disconnection of the collected and transmitted field measuring instrument, the acquisition transmitter will actively send information to the management system.

　　The data collection methods are divided into timing and real-time, which can be customized according to user settings. It has the advantages of fast and accurate data collection, and can quickly generate consumption statistics and analysis tables, payment documents and so on. In addition, the system also provides equipment management functions, such as alarm: unpacking alarm, undervoltage alarm, etc; Control function: prompt and close the valve for users in arrears; It also provides power failure data protection function, which can still read and monitor meters within 24-36 hours of power failure. The system also combines the SMS platform to send the alarm to the management system or notify relevant managers in the form of SMS.

　　4、 Application prospect

　　The application of GPRS Remote Wireless Data Acquisition and monitoring system enables gas companies to understand the operation status of gas flow meters / gas equipment of public service users at any time. Through the analysis of these data, it is convenient to find out possible hidden dangers in time, improve the management level of metering equipment and reduce the difference between supply and marketing. In addition, it can also know the gas consumption parameters of a single user at any time, including gas pressure, instantaneous flow, cumulative flow, etc., so as to master the gas consumption characteristics of the user, reasonably allocate gas resources, and master the user's gas consumption at any time to avoid arrears; Through the timely and accurate analysis of the gas consumption of all public service users, it provides basic data for the reasonable analysis, supply and allocation of the whole gas network, changes the low efficiency and cheating hidden danger of the previous manual table checking method, improves the service quality level of gas management, and is convenient for integration with the original charging system.

　　GPRS Remote Wireless Data Acquisition and monitoring system is widely used, which can be applied to gas, water and electricity remote monitoring or wireless automatic meter reading, oil / gas pipeline monitoring, oil / gas well / station monitoring, traffic monitoring, meteorological detection, environmental detection, other remote wireless data acquisition and transmission systems, etc. GPRS network remote data communication method solves the communication problem of remote monitoring system, which has incomparable advantages over other wired communication methods. Due to the wireless mode, the security of data transmission has been greatly improved. Of course, the implementation of this method also has some defects. For example, the reliability and real-time performance of GPRS communication mode need to be improved compared with CSD (circuit dialing) communication mode. However, with the gradual integrity of GPRS network and the continuous maturity of application technology, GPRS will be more and more widely used in other industrial fields.