1, Project background
For gas company, real-time monitoring of gas pipeline, temperature, pressure, flow and other information is a necessary means to eliminate potential safety problems, compared to the data transmission means in the early stage (such as: digital radio, cable), using a remote data acquisition device (DTU) + monitoring by wireless network, has more advantages apparently in cost savings and improving safety of the network.
With the wireless network, the gas company can transfer the real-time information to the monitoring center. The formation of distributed monitoring network to the monitoring center as the core radiation of the whole network, the online monitoring does not exist blind. And through GSM network, the alarm information SMS to inform the relevant operators. Keep abreast of first-hand information security, security risks will be extinguished in the bud.
2, system composition
Gas pipeline network monitoring system in three parts: monitoring center, data transmission terminal, terminal data collector.
The monitoring center includes WEB server, data server and PC monitoring platform, can be 24 hours of uninterrupted real-time data acquisition, dynamic display field of each monitoring site change data, automatic form report and data abnormal automatically send alarm messages, and foreign service personnel can access through the Internet monitoring platform for real-time view the corresponding data.
Terminal data acquisition including gas flow meter, pressure transmitter, temperature transmitter, gas pipeline flow, pressure, temperature and other data sent to DTU, and then through the operator network transmission to the monitoring center.
Network transmission equipment: for various interfaces and equipment acquisition work environment requirements, the F2X14 series DTU in Xiamen Four-Faith Communication Co. Ltd. as the acquisition and transmission equipment, through the network transmission, wireless remote monitoring of the gas pipeline network monitoring center. F2114 (GPRS DTU) is data transmission terminal, provide long distance wireless data transmission for users to use the network operators, support GPRS network, while supporting RS232 and RS485 (or RS422) interface, Transparent data transmission to achieve low power design, the minimum power consumption less than 1mA; to provide 5 I/0, can achieve digital input and output, pulse output, analog input, pulse count and other functions.
3, System topology
Communication terminal equipment and monitoring center in two ways, one is to use the public network operators, the other one is to use the APN/VPDN network.
3.1 Public scheme
Network topology:
The monitoring center with a server group as the center to receive data, center by ADSL Internet network connection, the public or public fixed IP dynamic IP+DNS resolution service.
1) Center public fixed IP: monitoring point directly to the center of the fixed IP initiates a connection, stable and reliable operation.
2) Public service center network dynamic IP+DNS: monitoring point by domain name addressing mode to connect to the DNS server, and DNS server connected to the public network dynamic IP, to establish a connection. This advantage can greatly reduce the cost of the fixed public network IP address, the disadvantage is correct speed and stability controlled by the DNS server.
3.2 Private Network
Network topology:
VPDN/APN line, also known as virtual private dial-up network, is a kind of VPN service, is a Virtual Private Dial-up dial-up users. Based on the network business to dial-up access online, is to use the bearing function of the IP neural network combined with the corresponding authentication and authorization mechanisms set up secure virtual private network, is a kind of technology in recent years with the development of Internet and the rapid development of the telecom operators. According to the classification, VPDN line, mobile, APN line.
The monitoring center through a APN access network by Mobile Corporation GRPS, F2114 operators designed card, both private fixed IP address in the same LAN. The data transmission between the terminal and the server platform uses end-to-end encryption, to avoid information leakage in the process of transmission. Both firewall and isolation. The IP address and port filtering on the firewall. This scheme for both real-time, safety and stability of the previous schemes have greatly improved, suitable for higher security requirements, more data points, real-time application environment is higher, in the case of funds is the best way to network.
4, Program Features
4.1, Stability: industrial high performance processor, able to withstand long-term harsh environment test, to ensure smooth communication; reliable network connection equipment to ensure the equipment redial function, always online.
4.2, Low cost: wireless data transmission terminal, use the operator’s GPRS network, without the need for network cabling, equipment installation is flexible and is not affected by the impact of geographical environment, single point cheap equipment, reduce wiring problems and reduce the cost.
4.3, Flexibility and Expansibility : standard communication protocol, the same time to facilitate the installation of the installation, commissioning, operation and maintenance.
4.4, Wide range: large number of gas pipeline monitoring, gas collection points may be located in remote areas. This scheme is used in wide coverage GPRS network, there is no blind area, can realize online monitoring in large range, can meet the monitoring system of gas pipeline network coverage requirements.
4.5, Timeliness: when the data is abnormal, etc., to be able to send text messages to the person in charge by the GSM network to send SMS alerts in a timely manner, to avoid security risks.
