In the modern urban transportation system, as an efficient and convenient mode of transportation, the network communication system behind the subway is crucial. Industrial switches play a core role in the subway network, especially the configuration of redundant ring network switches, which plays a decisive role in ensuring the stable operation of the subway system.
Overview of Industrial Switch Fundamentals
Industrial switches, also known as industrial Ethernet switches, are designed specifically for the industrial control field. Unlike ordinary commercial switches, it has carrier grade performance characteristics and can withstand harsh working environments such as high temperature, high humidity, and strong electromagnetic interference. Its product line is rich, port configuration is flexible, supports standard and private ring network redundancy protocols, and the protection level is usually not lower than IP30.
Industrial switches are divided into industrial unmanaged switches and industrial managed switches. Non managed switches are positioned at the low end and have a high usage volume. They can achieve basic message routing functions, automatically detect network device speeds, and identify and remember devices through a "MAC address table". However, they do not have communication detection and redundant configuration functions. Network managed switches are positioned as high-end, powerful, and commonly used in backbone networks. It not only automatically interacts with network devices, but users can also manually configure port network speed and traffic control. It has advanced functions such as SNMP (Simple Network Management Protocol), port mapping, VLAN (Virtual Local Area Network), priority ranking, etc., and can form redundant networks.
The demand for industrial switches in subway networks
The subway system consists of numerous subsystems, such as signal control system, train control system, power monitoring system (SCADA), integrated monitoring system, automatic fare collection system (AFC), etc. Each subsystem requires stable and high-speed network communication support. Taking the signal control system as an example, its reliability, safety, stability, and real-time performance directly determine the safety of train operation. Therefore, high-performance and high reliability industrial grade switches are needed to form the backbone network.
The operating environment of the subway is complex, with a large amount of electromagnetic interference, and there are significant differences in environmental conditions in areas such as stations and tunnels. This requires industrial switches to have strong anti-interference ability and stability, and be able to continue working normally in harsh environments. At the same time, the subway network requires real-time transmission of a large amount of data, including train operation status, equipment operation parameters, video monitoring information, etc. Therefore, industrial switches must have large bandwidth to ensure fast and stable data transmission.
Analysis of Redundant Ring Network Switch Configuration Example
Taking a certain subway line as an example, a redundant ring network switch configuration is adopted in its comprehensive monitoring system. The system is independently networked and utilizes its own industrial grade Ethernet switches and optical fibers provided by the communication system to build an industrial grade Ethernet, providing support for urban construction communication systems and security transmission.
In this redundant ring network, an industrial switch that supports Media Redundancy Protocol (MRP) is used, which complies with the IEC62439-2 standard. Each ring network supports up to 50 devices, with a typical reconfiguration time of 200ms. All links support MRP and enable the protocol, and devices are interconnected through ring network ports. A device in the ring network acts as a redundancy manager, while other devices act as redundant clients, and all partner ports within the ring are set to be the same.
During the configuration process, the first step is to perform network topology planning. Although topology configuration is not a necessary condition for MRP to function properly, reasonable topology planning can help with troubleshooting. Then assign a device name to each PROFINET device and set a watchdog time greater than 200ms by modifying the number of update cycles (such as setting the update cycle number to 120 and the update time to 2ms, then the watchdog time is 240ms) to ensure that IO device failures are not falsely reported during network restructuring.
The advantages of redundant ring networks
High reliability: The redundant structure of the medium significantly improves the availability of the equipment. When a single device fails, it will not affect the communication of the entire network, as data can be transmitted through backup paths, ensuring the continuous operation of various subway systems. For example, in the signal system, even if a switch fails, train control signals can still be transmitted through redundant paths to ensure the safety of train operation.
Easy to maintain: Due to the redundancy capability of the network, maintenance work can be carried out without time pressure, and the factory does not need to shut down, reducing the risk of operational interruption caused by maintenance. At the same time, in the event of a network failure, the fast network diagnostic function can accelerate the speed of troubleshooting and reduce production downtime costs caused by the failure.
Flexibility: Redundant ring network switches support multiple network topologies and can flexibly arrange network topologies according to the needs of different areas and subsystems of the subway. For example, a topology structure combining star and ring can be used in the station area, and a ring topology structure can be used in the long-distance transmission area of the tunnel to improve the stability and reliability of the monitoring system.
Application of industrial switches in other subway scenarios
Distribution line monitoring: Industrial network switches connect various power monitoring equipment, collect parameter information such as power load, voltage, and current, monitor and analyze the working status of the lines in real time, timely detect line abnormalities and potential dangers, and ensure the safe and stable operation of the subway distribution system.
Video surveillance: connected to video surveillance equipment to achieve real-time monitoring of distribution stations, stations, tunnels, and other areas. With the high bandwidth transmission capability of industrial switches, smooth transmission of high-definition videos and remote monitoring can be achieved, improving the efficiency of subway security management.
Automatic ticketing system: Ensure stable data communication between various terminal devices and servers in the AFC system, quickly process ticketing information, and improve the efficiency of passenger entry and exit.
The redundant ring network switch configuration of industrial switches is a key support for the stable operation of subway networks. With the continuous development of subway construction, the performance and reliability requirements for industrial switches will also continue to increase, and their application in subway networks will become more extensive and in-depth.