“With the rapid development of my country’s economy, the construction of subway engineering projects is also in the process of rapid development and continuous improvement. As the preferred mode of transportation for people, the comfort and convenience of the subway has attracted more and more attention, and safe and reliable operation is particularly important.
With the rapid development of my country’s economy, the construction of subway engineering projects is also in the process of rapid development and continuous improvement. As the preferred mode of transportation for people, the comfort and convenience of the subway has attracted more and more attention, and safe and reliable operation is particularly important.
Figure 1 Beijing’s intricate subway lines
Do you know what the integrated system of the subway comprehensive monitoring system includes?
• Fire Alarm System (FAS);
• Environmental and Equipment Monitoring System (BAS);
• Power Supervisory Control System (SCADA);
• Screen Door/Safety Door System (PSD).
At the same time, the ISCS system is interconnected with the following systems:
• Broadcasting System (PA);
• Closed-circuit television surveillance (CCTV);
• Automatic Fare Collection (AFC);
• Access Control System (ACS);
• Signal System (SIG);
• Clock system (CLK);
• Passenger Information System (PIS);
• Communication centralized alarm system.
Thanks to the complete operation control network, the subway has become more safe and comfortable, and every system is an orderly escort for the safety of the subway. Today, let’s take a look at how the subway screen door system (PSD) works.
The platform screen door of urban rail transit is a high-tech product integrating construction, machinery, materials, electronics and information. It isolates the track from the waiting area of the platform. Close the sliding door.
The subway screen door system based on CAN bus means that the middle PSD (central interface panel), PSA (remote alarm panel) and each DCU (gate control unit) of the system are a network node mounted on the CAN bus. CAN The bus distribution structure can ensure that the failure of one node of Rehe on the network will not affect the normal operation of other nodes in the network, and the whole process control of the screen door through the network, the modification of operating parameters and other tasks.
Figure 2 The composition frame of the subway screen door system
• PSC: central interface panel, PSC is the core of the screen door/safety control system, each station is equipped with a set of PSC for the screen door/safety door equipment;
• PSD: subway screen door, which can be divided into three parts: sliding door, fixed door and emergency door;
• PSA: remote alarm panel, used for monitoring the status of the screen door, diagnosing the fault of the screen door, running status, etc.;
• PSL: local control panel, the combination of electrical switches on the platform side to control the operation of the screen door on this side, allowing station personnel and train drivers to operate the screen door when the train system control fails;
• DCU: The door control unit is the control device for the sliding door motor. Each sliding door unit of the screen door is equipped with a door control unit, which is installed in the top box.
Figure 3 Subway screen door system division
The screen door control system still uses hard-wired transmission on some important nodes and commands, such as between PSC and signal system, between PSB and PSL (local control panel), and the sending and feedback of the opening and closing commands of the screen door. To use hard-wired transmission, in addition to the DCU connection via the CAN bus, the PSC communicates with the LESS (Local Environmental Monitoring System) via RS-485. Communicates with PTE via RS232, and communicates with the Display via Ethernet. The subway screen door system is shown in the figure below.
In view of the particularity of the subway operation site, it is necessary to protect the external and own signals, isolate the impact of interference on the bus data communication, and ensure safety and reliability. At present, the authoritative standard for subway screen doors is “CJ/T 236-2006 Urban Rail Transit Platform Screen Doors” issued by the Ministry of Construction of the People’s Republic of China.
This standard specifies the technical requirements, testing and packaging, transportation and storage of screen doors for urban rail transit platforms. In the standard 184.108.40.206 electromagnetic compatibility test, it is clearly required that the screen door must pass GB/T 17626~GB/T 17626.6, GB/T 17626.8, GB/T 17626.11.
Figure 4 CJ/T 236-2006 Electromagnetic Compatibility Requirements for Screen Door Systems
In order to meet the screen door standard proposed by the Ministry of Construction of the People’s Republic of China, the field data bus interfaces of each DCU, namely CAN-bus interface, RS-485 interface, RS-232 interface, etc., need to be isolated from power supply and communication to completely cut off the ground ring between modules. road interference. Of course, it is also necessary to isolate the power supply at the same time.
ZLG Zhiyuan Electronics has been focusing on signal isolation and transmission conditioning for 20 years, providing reliable and leading signal isolation and acquisition template-level solutions for the industrial field.
ZLG Zhiyuan Electronics has launched a surface mount isolation module in order to meet market demands and technological innovations based on years of technology accumulation and customer development trends. Compared with traditional designs, surface-mount products not only have higher integration and reliability, but also support all commonly used SMD packages in the industry. They are suitable for occasions requiring high-stability CAN bus communication, and can maximize the user experience. The production efficiency can help users improve the protection level of bus communication.
At present, isolated CAN transceivers, isolated RS-485 transceivers, etc. have been launched. The isolation voltage is up to 3500V, and the ultra-wide temperature adaptation range can conquer complex and harsh industrial sites.