Design and Implementation of a GSM wireless data transmission system with Ethernet interfaces (1)

With the rapid development of computer control systems, we can see that various control systems are widely used in modern production and life. They are all advanced control software developed based on modern control theory. To ensure the stable operation of these control systems for a long period of time, you must monitor and control the operating status of the system in real time. For a remote job control system, the required monitoring information must be obtained from the controlled object, after effectively analyzing and processing the obtained information, the system issues control commands for the controlled system. Therefore, the remote data transmission system is one of the most important components of various remote monitoring and control systems.

1. Overall monitoring system architecture

Although the current Remote Monitoring System is economical and practical, the cable data transmission method limits its usage, and it is difficult to meet the current needs. Combined with the advantages of the Monitoring System Based on Industrial Ethernet and GSM wireless network, this paper proposes a new integrated monitoring system architecture, as shown in System Structure 1.

As the Internet network gradually covers the whole country and the GSM network is increasingly becoming the most widely used and widely used wireless communication network in China, the system solution fully integrates the two public networks on this basis, the GSM network can be used to send control commands to each subnode distributed in the control site and receive data collected from each subnode; the Ethernet interface can also be used to communicate with the computer or display screen of the control center. In this way, the collected data can be transmitted to multiple computers or devices in the control center while monitoring and controlling remote devices, so as to connect the control system and management system, it effectively solves the interconnection problem of integrated systems for information collection, information analysis, information processing, information storage, and information output.

According to the comprehensive monitoring system structure, the remote monitoring system is mostly composed of three parts: Control Center, monitoring center node and remote monitoring terminal.

1.1 GSM wireless communication control terminal

The general architecture 2 of the GSM wireless communication terminal is shown in. Its location is in the control site of the system to be tested. The function is to collect data from the test site, analyze and process the data in the control center, encode the data according to the SMS protocol, and send the data to the central node of wireless communication through the GSM network; from the structure diagram, we can see the components of the wireless communication terminal, and the data transmission process shows that the control terminal is also responsible for receiving instructions from the wireless communication center node, and forming a closed loop from detection to control.

1.2 GSM wireless communication center node

The general architecture 3 of the GSM wireless communication center node is shown in. It is the key to the entire measurement and control system. It is located between the communication terminal and the control center. It is a transfer station for data and command transmission. Its main function is to receive field data from the communication terminal, after analysis, the data is stored in E2PROM, and the command is sent from the master control computer of the Control Center. The command is sent from the Ethernet interface to the communication terminal, control the corresponding monitoring equipment.

1.3 Control Center

The main Architecture 4 of the control center is shown in. It is at the top of the system. The main control computer and display device are connected together through an Ethernet switch to form a LAN, sharing the data collected by the communication center node. It is responsible for receiving the data collected on the site and storing it in the database. After making corresponding decisions on the data analysis, the communication center node sends control commands to the communication terminal, at the same time, you can use a large screen display to display the running status of the objects to be tested in real time.

The core of the entire wireless data transmission system is the microprocessor, GSM module, and Ethernet module, which can be completed with corresponding input and output modules, the module is clear, the task scheduling is simple, the data processing capacity is small, and the real-time requirement is not high. Therefore, the system selects the architecture of the microcontroller + control system software.