Subway platform door display system and display method based on CAN communication
By using CAN communication to communicate between the platform door management host and the display unit, the problem of limited information coverage and low management efficiency in existing subway platform display systems has been solved, enabling passengers in front of each platform door to access a rich display system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-24
- Publication Date
- 2026-07-03
Smart Images
Figure CN122331852A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of rail transit technology, and in particular to a subway platform door display system and display method based on CAN communication. Background Technology
[0002] With the continuous improvement of subway intelligence, platform screen door display systems have become a key component in ensuring operational efficiency, undergoing a transformation from basic functions to intelligent services. Currently, the mainstream approach to subway platform screen displays involves equipping several suspended displays on the platform, rather than each platform screen door having one, potentially preventing some passengers from accessing important information promptly. Existing systems typically display train time information, lacking information about platform screen doors and the train's interior, resulting in limited content. Some subway platform screen doors have embedded displays above them, but these are controlled by the door control system, displaying only platform screen information and potentially interfering with the main tasks of the door control system. Updating the display program requires technicians to perform local operations on each screen individually, hindering centralized management and consuming significant manpower.
[0003] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art. Summary of the Invention
[0004] The purpose of this invention is to provide a subway platform door display system and method based on CAN communication, which has a wide information coverage, enables centralized management of the display system, makes the display and updating of the display system more efficient, has high information synchronization efficiency, and allows for diversified display content.
[0005] To achieve the above objectives, the present invention provides a subway platform door display method based on CAN communication, comprising: The platform door management host and the display unit in the display system exchange message commands via a CAN bus. The message commands include identifiers and data fields. The identifier includes: Device type, used to identify the sender of this message instruction; Message type, used to identify different message types; The display unit number is used to identify the display unit that receives or sends the message instruction; The data field is used to store the specific message content.
[0006] The message instruction includes a first message instruction sent by the platform door management host to the display unit, which instructs the display unit to display or update according to the first message instruction; In the first message instruction: The device type is identified as the platform door management host; The message types include: display information and update information.
[0007] If the display unit number in the first message instruction is set to a broadcast address, then the platform door management host sends the first message instruction to all the display units.
[0008] If the display unit number in the first message instruction is set to the display unit number value of a certain display unit, then the platform door management host sends the first message instruction individually to the display unit with the display unit number value.
[0009] The displayed information includes: vehicle information, platform door information, passenger information, and promotional information.
[0010] The first message instruction includes a display message instruction. When the message type in the display message instruction is set to display information, the display stage begins, and the platform door management host sends a display message instruction carrying display information to the display unit.
[0011] The update information includes: updating the display content and updating the display program.
[0012] The first message instruction includes an update message instruction. When the message type in the update message instruction is set to update information, the update phase begins, and the platform door management host sends an update message instruction carrying update information to the display unit.
[0013] The identifier of the update message instruction also includes: key information used to identify different update message instructions in the update phase; The update message instruction includes: a first update message instruction, a second update message instruction, and a third update message instruction; The update methods include: The platform door management host sends a first update message instruction to the display unit. In the first update message instruction, the key information is set as first type of information, the data field contains a length flag, and the remaining bytes in the data field are filled with the total length of the specific content of the update information in the second update message instruction. The platform door management host sequentially sends multiple second update message instructions to the display unit. In the second update message instructions, the key information is set as first type information, and the data field is filled with the specific content of the update information. The platform door management host sends a third update message instruction to the display unit. In the third update message instruction, the key information is set to the second type of information, and the data field is filled with an update check value.
[0014] The method for calculating the check value includes: calculating the check value using the CRC algorithm based on the binary data of the complete update information. The platform door management host uses the method described above to calculate the update check value and fills it into the data field of the third update message instruction. After receiving the update message instruction, the display unit calculates the received verification value using the method for calculating the verification value, compares the received verification value with the update verification value, and if they match, the display unit stores the received update information.
[0015] The identifier also includes a display content ID number, which is used to identify the content that needs to be displayed or updated by the display unit. The display unit displays or updates the corresponding content according to the received display content ID number.
[0016] The message instruction includes a second message instruction sent by the display unit to the platform door management host, used to report the status of the display unit to the platform door management host; In the second message instruction: The device type is identified as the display unit; The message type includes: the status information of the display unit; The display unit number is set to the display unit number value of the display unit that sent the second message instruction.
[0017] The display unit periodically sends the second message instruction to the platform door management host.
[0018] The message instruction includes a verification success message sent by the display unit to the platform door management host. If the verification by the display unit is successful, the display unit sends the verification success message to the platform door management host. The verification success message includes: The device type is identified as the display unit; The message type is the same as the message type in the first message instruction received by the display unit; The display unit number is set to the display unit number value of the display unit that sent the verification success message; The key information is set as the second type of information; The data field is populated with an update check value.
[0019] The message instruction includes a verification failure message sent by the display unit to the platform door management host. If the verification by the display unit is inconsistent, the display unit sends a verification failure message to the platform door management host. In the verification failure message: The device type is identified as the display unit; The message type is the same as the message type in the first message instruction received by the display unit; the display unit number is set to the display unit number value of the display unit that sent the verification success message; The key information is set as the second type of information; The data field is filled with a verification failure flag.
[0020] After receiving the verification failure message, the platform door management host re-sends the update message instruction to the display unit using the update method.
[0021] The identifier in the message instruction also includes a message check value, used to ensure the data correctness of the message instruction.
[0022] The present invention also provides a subway platform door display system based on CAN communication, for implementing the aforementioned subway platform door display method based on CAN communication, comprising: a platform door management host and a display system connected via a CAN bus; The display system includes multiple display units, each of which is located at a platform door, and the number of display units is the same as the number of platform doors. The platform door management host is used to send display message instructions carrying display information and update message instructions carrying update information to the display unit; The display unit is used to send a second message instruction carrying the status information of the display unit to the platform door management host.
[0023] The platform screen door is a full-height door, and the display unit is fixedly installed on the top of the full-height door.
[0024] The platform screen door is a half-height door, and the display unit is fixedly installed on the side of the half-height door.
[0025] The CAN bus has two redundant lines and uses twisted-pair shielded wire for connection, with a communication rate of 125Kbps.
[0026] The display unit includes: a controller, and a display screen and a memory connected to the controller; The memory includes a first memory and a second memory. The first memory is used to store the received display content, and the second memory is used to store the received application program.
[0027] Each of the display units has a unique display unit number.
[0028] The present invention has the following beneficial effects: Wide information coverage: The mainstream platform display method involves setting up several displays (fewer than the number of platform doors) high on the platform. Multiple platform doors share one display, and passengers far from the display may not be able to obtain information in a timely manner. This invention sets up a display unit on each pair of platform doors, ensuring that passengers in front of each pair of doors can obtain important information. The display unit is installed in a prominent and unobstructed position. A groove can be cut into the existing full-height door's metal cover plate to embed the display, and then a transparent glass is used to isolate it from the external environment; alternatively, a groove can be cut into the existing half-door's side metal cover plate to embed the display, and then a transparent glass is used to isolate it from the external environment.
[0029] Centralized management is possible: all display units of the display system are connected to the platform door management host. When it is necessary to update the display content and update the program, the content is uniformly distributed through the platform door management host, and each display unit can quickly and efficiently complete the update.
[0030] High information synchronization efficiency: The display system, gate control system, and platform screen door management host are all connected to the CAN bus. Each unit of the display system can exchange messages with the platform screen door management host, while the platform screen door management host can selectively display the interaction status with other systems on the display screen. Therefore, it can improve the overall equipment operating efficiency and facilitate system function expansion.
[0031] The display content is diversified: mainstream platform screen displays lack platform screen information and other system information, while the display units of this invention can display not only train information, platform screen status, and promotional information, but also selectively display other system information. The display units have sufficient capacity to store content, providing flexibility for content updates and replacements. Attached Figure Description
[0032] Figure 1 This is a schematic diagram of a subway platform door display system based on CAN communication provided by the present invention.
[0033] Figure 2 This is a schematic diagram of the display unit.
[0034] Figure 3 This is a schematic diagram illustrating the method for updating the displayed content in a display unit.
[0035] Figure 4 This is a schematic diagram illustrating the method by which the display unit updates the display program. Detailed Implementation
[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clearly illustrate the embodiments of the present invention. Please refer to the drawings to make the objectives, features, and advantages of the present invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the present invention, should still fall within the scope of the technical content disclosed in the present invention.
[0037] Given the limitations of current platform screen door display systems, developing a platform screen door display system with wide information coverage, centralized management, high information synchronization efficiency, and diversified display content is of great practical significance.
[0038] like Figure 1 As shown, this invention provides a subway platform door display system based on CAN communication, comprising: a platform door management host 1 and a display system 2 connected via a CAN bus. The display system 2 includes multiple display units 21, each of which is located at a platform door (not shown in the figure). The number of display units 21 is the same as the number of platform doors, i.e., one display unit 21 is provided at each pair of platform doors. For full-height doors, a groove can be cut into the existing metal cover plate of the full-height door, and the display unit 21 is set above the platform door, embedded in the groove. The display unit 21 is fixed to the center of the cover plate with screws, and then isolated from the external environment using transparent glass. For half-height doors, a groove can be cut into the metal cover plate on the side of the existing half-height door, and the display unit 21 is fixed in the groove with screws, and then isolated from the external environment using transparent glass.
[0039] Display system 2, platform screen door management host 1, and platform screen door control system (not shown in the diagram) are all connected to a redundant CAN bus. The CAN bus uses twisted-pair shielded cable for connection, and the communication rate is set to 125Kbps to ensure stable and reliable data transmission in the subway environment.
[0040] The platform screen door management host 1 broadcasts message commands via the CAN bus. Each display unit 21 in the display system 2 can interact with the platform screen door management host 1. Simultaneously, the platform screen door management host 1 can selectively display the interaction status with other systems on each display unit 21. Different device nodes and message types are distinguished by fields in the message commands. The device node refers to the device node that sends the message command; the device node can be the platform screen door management host 1 or display units 21 with different serial numbers.
[0041] Display system 2 includes all display units 21 installed throughout the station and internal and external interfaces for each display unit 21. The display units 21 are built on 32-bit ARM Cortex-M series microcontrollers. Display units 21 with different serial numbers are distinguished by hardware DIP switches. The serial numbers of the display units 21 are determined before the project is activated, and each display unit 21 has a unique serial number. In addition to sending message commands via broadcast, the platform gate management host 1 can also send message commands to display units 21 with specified serial numbers. The sent message commands contain serial number information, and only the display unit 21 with the corresponding serial number can respond to the message type in the message command.
[0042] like Figure 2 As shown, each display unit 21 includes a controller 211, a display screen 212 connected to the controller 211, and a memory 213. The internal interface of the display unit 21 refers to the interface between the controller 211 and the memory 213 and the display screen 212, while the external interface refers to the CAN interface between the display unit 21 and the platform gate management host 1. In this embodiment, the memory 213 includes an SD card and a Flash memory. The SD card is used to store display content, and the Flash memory is used to store application programs.
[0043] In this embodiment, communication between the platform screen door management host 1 and the display system 2 uses the frame format defined by the CAN 2.0B protocol. The message commands exchanged between the platform screen door management host 1 and the display system 2 include a 29-bit identifier (ID) and an 8-byte data field. The identifier includes: a device type field (2 bits), a message type field (8 bits), a display content ID field (8 bits), a display unit serial number field (6 bits), a message verification field (4 bits), and a key information field (1 bit). The message verification field is used to ensure the correctness of the frame data; it XORs the 8 bytes of the data field and retains the lower 4 bits to verify the correctness and integrity of the message data. The key information field is used to distinguish message frames in the update process (described in detail below). In addition to the 29-bit identifier (ID), there is also an 8-byte data field, which can be used to transmit specific content data according to different message types. The messages sent by the platform screen door management host 1 to the display unit 21 and the messages sent by the display unit 21 to the platform screen door management host 1 both follow the format defined above.
[0044] The messages sent by different device nodes on the CAN bus can be identified by the device type field (2 bits) in the message command. In this embodiment, 0x1 indicates that the message command sent by the platform gate management host 1 to the display unit 21, and 0x2 indicates that the message command sent by the display unit 21 in the display system 2 to the platform gate management host 1.
[0045] When the device type field is 0x1, it represents a message instruction sent by the platform screen door management host 1 to the display unit 21. The CAN message sent by the platform screen door management host 1 has its message type determined by the message type field (8 bits). The message type includes vehicle information, platform screen door information, passenger notification information, and promotional information. In this embodiment, 0x11 represents train time information (vehicle information), 0x12 represents train departure station information (vehicle information), 0x13 represents platform screen door information, 0x14 represents alarm information (passenger notification information), 0x15 represents promotional information, 0x1E represents updated display content, and 0x1F represents updated display program.
[0046] When the device type field is 0x2, it represents a message instruction sent by display unit 21 to platform door management host 1. In this case, the message type field (8 bits) indicates the status of display unit 21. In this embodiment, 0x21 indicates that the display unit is operating normally, and 0x22 indicates that the display unit is faulty. Each message instruction sent by different display units 21 carries a unique display unit serial number field, which platform door management host 1 can use to monitor each display unit 21. The display system 2 periodically (at 10-second intervals) sends message instructions to platform door management host 1 (in this embodiment, each display unit 21 sends messages sequentially at 2-second intervals). Platform door management host 1 monitors whether the display unit 21 is operating normally using these message instructions. When the device type field is 0x2, the message type field in the message instruction sent by display unit 21 to platform door management host 1 can also be "update display content 0x1E" or "update display program 0x1F," which will be explained in detail below.
[0047] The display unit 21 receives a CAN message from the platform door management host 1, which also contains a display content ID number (8 bits). The display unit 21 displays the corresponding content based on the received ID number. Each content displayed on the display screen 212 has a unique corresponding ID number within the display unit 21. For example, if the message type received by the display unit 21 is platform door information, and the display content ID number in the message frame is n, where n is an image stored in the internal memory 213 of the display unit 21 (used to display platform door information), then the display unit 21 overlays the image with the text from the actual platform door information (e.g., platform door open to the correct position), and finally displays it on the display screen 212. If the message type received by the display unit 21 is promotional information, and the display content ID is m, where m is a video clip or image, the display content is stored in the display unit 21 using a unique ID. The corresponding image or video content is defined by the display content ID number in the frame ID. The display unit 21 displays the corresponding content based on the display content ID number in the message command sent by the platform door management host 1.
[0048] When the display content on display unit 21 needs to be updated, the platform gate management host 1 sends a message command indicating that the display content needs to be updated. The CAN message frame ID consists of the following: device type field is 0x1, message type field is 0x1E, display content ID number field is the ID of the content to be updated (e.g., updating the content with display ID x to new content), display unit serial number field is the serial number of this display unit 21 (a unique serial number confirmed by the hardware DIP switch), message verification field is the 8-byte verification value of the message data field of this frame (after XORing all bytes, the lower 4 bits are retained; each frame message has an 8-byte data field, so the frame ID of each frame message contains a message verification field), and key information (1 bit) is 0x0 or 0x1. When the key information is 0x0, the message indicates the total number of content update frames or the specific content to be updated (distinguished by the data field). When the key information is 0x1, the message indicates a CRC check frame. In this embodiment, if the key information is 0x0 and the first two bytes of the data field are 0x55AA, then the subsequent bytes represent the total number of updated content frames. If the key information is 0x0 and the display content ID field is 0xAA (to distinguish them, the display content ID field in the updated content frame ID no longer represents the displayed content; for example, when the display content ID is n, the display content ID in the total frame count message and the verification message is n, but the display content ID in the specific updated content message is 0xAA. This design is to distinguish the special case where the specific updated content contains 0x55AA (the specific content happens to contain 0x55AA data), and the total frame count message and the specific updated content message need to be distinguished by the display content ID field), then the 8-byte data field represents the specific updated content. If the key information is 0x1, then the data field represents the CRC checksum of the updated content. Depending on the different message types of the message instruction, the data field can be filled with the content length (total number of frames), content data, and CRC checksum.
[0049] When updating the displayed content, the platform gate management host 1 first sends a length frame of the updated content. The identifier (ID) in the message instruction of this frame is filled with the device type field, message type field, display content ID number field, display unit serial number field, etc. The first two bytes of the data field of the message instruction are 0x55AA, and the following bytes are the content length. For example, if the image content with display ID x that needs to be updated has a length of 500 bytes, then the 8 bytes of the data field are 0xAA, 0x55, 0xF4, 0x01, 0, 0, 0, 0 (500 converted to hexadecimal, low byte first, high byte last, unused bytes are 0).
[0050] After sending a length frame, the platform door management host 1 continues to send content frames. The identifier ID and data field in the content frame message command are as described above. The data field in the content frame message command contains the new display content to be updated (whether it is an image or video, it can be converted into binary data during transmission and storage. Depending on the size of the content, the display content is transmitted sequentially in several frame messages). The platform door management host 1 transmits the updated display content to the display unit 21 by sending multiple consecutive CAN messages.
[0051] After the updated display content transmission is complete, the platform door management host 1 sends a content verification frame (a CRC checksum calculated based on the complete binary data of the new display content to be updated; the CRC checksum is placed in the data field of the content verification frame message instruction). The composition of the content frame message instruction is as described above. The display unit 21 calculates the CRC-b for the received multi-frame message instructions using the same calculation method and compares it with the CRC checksum in the data field of the received content verification frame. If the two are the same, it indicates that the display unit 21 has received the complete updated display content and stores the updated display content to the SD card. The update should be performed during non-metro operating hours.
[0052] Display unit 21 stores updated display content to the SD card: Display unit 21 stores the verified updated display content into the SD card as a file, named after the display ID. If the ID file does not exist on the SD card, it creates the file and stores it on the SD card. If the ID file already exists on the SD card, the content of the ID file is rewritten, thereby updating the display content of the ID file. Subsequently, when display unit 21 displays the ID content, it should display the updated content.
[0053] When the display program on display unit 21 needs to be updated, the update method is similar to the method for updating the display content. The platform door management host 1 first sends a message indicating the total number of frames for the update program. Then, it sequentially sends several CAN messages containing the specific content of the update program, with the message data field containing the new program content. After the specific content of the update program has been sent, the platform door management host 1 sends a CRC check frame for the update content. Display unit 21 verifies the update program content; if the verification passes, the update program runs. (See below for specific steps.) Figure 4 (Detailed description).
[0054] In one specific embodiment of the present invention, such as Figure 1 As shown, the platform screen door management host 1 and the display system 2 are connected via a CAN bus, and the same number of display units 21 are provided according to the number of platform screen doors. Figure 1Taking a platform with 30 display units 21 on one side as an example, each display unit 21 is connected to a redundant CAN bus. Each display unit 21 has a unique serial number determined by a hardware DIP switch. The CAN message command sent by the platform door management host 1 contains a display unit serial number field (6 bits). Usually, the platform door management host 1 sends messages to all display units 21 in broadcast form (i.e., the unit serial number field is 0x3f, and the message command contains the address / serial number of all display units). By changing the display unit serial number field, messages can also be sent to specific display units 21. The platform door management host 1 can fill in different display unit serial number fields according to the actual situation.
[0055] Display unit 21 is configured with CAN message filtering, only receiving and parsing CAN message commands that are valid for it. When display unit 21 receives a CAN message command with the following characteristics: Device type field 0x1 (indicating a message sent by platform screen door management host 1), message type field 0x11 (indicating train time information), and data field containing the current time and train arrival time, display unit 21 displays the train arrival time and dynamically displays a countdown on display screen 212 based on the current time. When display unit 21 receives a CAN message command with the following characteristics: Device type field 0x1 (indicating a message sent by platform screen door management host 1), message type field 0x12 (indicating train originating station information), and data field representing the train originating station ID, display unit 21 displays the corresponding originating station information according to the agreed-upon ID (display unit 21 searches the originating station ID file in the SD card; each station corresponds to a unique ID. The originating station file is stored in the same way as the displayed content and can be updated by updating the displayed content (0x1E message)). When display unit 21 receives a CAN message instruction with the following structure: Device type field 0x1 in frame ID (indicating a message sent by platform door management host 1), message type field 0x13 (indicating platform door information), and 8 bytes of data field containing platform door status information (filled starting from the least significant bit, unused bytes are filled with 0), where 0x1 in the data field indicates the platform door is open (i.e., the first byte of the data field is used), then display unit 21's screen 212 displays the open door information; 0x2 in the data field indicates the platform door is closed, then display unit 21's screen 212 displays the closed door information. When display unit 21 receives a CAN message instruction with the following structure: Device type field 0x1 (indicating a message sent by platform door management host 1), message type field 0x14 (indicating alarm information), and data field representing specific fault information (a fault code table file is stored on the SD card; the fault information code in the data field of the CAN message is a number; display unit 21 queries the fault code table file based on the received fault information code to obtain the fault text information and displays the fault text information on screen 212), then display unit 21 displays the corresponding fault information. When the CAN message command received by display unit 21 is: Device type field 0x1 (indicating a message sent by platform gate management host 1), message type field 0x15 (indicating promotional information), and data field is promotional information ID (the SD card stores many display contents with unique IDs; display unit 21 queries the corresponding ID file on the SD card based on the received ID), then display unit 21 plays the content with that ID (which may be an image or video). The calculation methods for the display content ID field, display unit sequence number field, and current frame message verification field in the above message command are consistent with the description above. When the message type field is 0x15 (promotional information), the display content ID is the same as the data field ID.After the display unit 21 successfully executes the above message command, it will reply to the platform door management host 1 with the received message command as is (except that the device type field is changed to 0x2, and the other fields and data fields are consistent with the received message).
[0056] like Figure 2 As shown, in this embodiment, the controller 211 uses an STM32 microcontroller, the memory 213 includes an SD card, and each display unit 21 is equipped with an SD card for storing display content. The STM32 microcontroller receives CAN messages sent by the platform gate management host 1 (using two redundant CAN channels; if one CAN channel fails, the other can still transmit messages, ensuring stable communication between the platform gate management host 1 and the display unit 21), and parses the messages to perform corresponding operations, such as retrieving and displaying content from the SD card, and updating the stored content on the SD card. The STM32 microcontroller updates the content of the SD card and drives the display screen 212 to display the corresponding content via the SPI protocol.
[0057] like Figure 3 As shown, when display unit 21 updates the displayed content, the 29-bit identifier (ID) in the received CAN message is: Device type field 0x1 (indicating the message was sent by platform gate management host 1), message type field 0x1E (indicating updated playback content), and key information field 1 bit is 0 or 1. The key information field is used to distinguish different message frames in the update process. According to the data field in different message frames, it can be filled with content length (total number of frames), content data, and CRC check frame. The data field of the first frame 0x1E message instruction sent by platform gate management host 1 contains the total number of frames updated this time. Then, the STM32 microcontroller of display unit 21 puts the updated content in the subsequently received message frames into the RAM (temporary storage) area. After the updated content is transmitted, the STM32 microcontroller of display unit 21 receives the CRC check value in the check message. The STM32 microcontroller calculates the CRC-b of the updated content in the RAM area and compares it with the CRC check value. If the check matches, it will reply with a message frame that is the same as the received message (except that the device type field is changed to 0x2, and the other fields and data fields are the same as the received message). If there is a discrepancy, a verification failure message is sent back (except that the device type field is changed to 0x2, all 8 bytes of the data field are set to 1, and other fields are consistent with the received message). After successful verification, the STM32 microcontroller of display unit 21 writes the updated content from the RAM area to the SD card via the SPI protocol. The STM32 microcontroller then displays the corresponding content based on the received display content ID. If the platform gate management host 1 does not receive a successful verification message, it needs to update again. If both updates fail, display unit 21 retains the original display content for that ID.
[0058] like Figure 4As shown, when the display unit 21 updates its program, the relevant CAN message is as follows: Device type field 0x1 (indicating the message is sent by the platform gate management host 1), message type field 0x1F (indicating an update to the display program), and key information field 1 bit. If the key information is 0x0 and the first two bytes of the data field are 0x55AA, then the subsequent bytes of the data field represent the total number of update content frames; if the key information is 0x0 and the display content ID number field is 0xAA, then the 8 bytes of the data field represent the specific update content; if the key information is 0x1, then the data field represents the CRC checksum of the update content. The first frame 0x1F message data field sent by the platform gate management host 1 should contain the total number of frames updated this time. Then, the STM32 microcontroller of the display unit 21 enters the bootloader and puts the received update content into the RAM area. After the updated content is transmitted, the STM32 microcontroller in display unit 21 receives the CRC checksum. The bootloader program of the STM32 microcontroller calculates the CRC-b value from the RAM area and compares it with the CRC checksum. If they match, the same message (except the device type field is changed to 0x2, and all other fields and data fields are the same as the received message) is sent back to the platform door management host 1. The STM32 microcontroller writes the updated content from the RAM area to the Flash and runs the new program. If they do not match, a checksum failure message is sent back (except the device type field is changed to 0x2, all 8 bytes of the data field are 1, and all other fields are the same as the received message). If the platform door management host 1 does not receive a checksum success message, the update needs to be performed again. If both updates fail, the original display application runs in the Flash.
[0059] This invention, "A Subway Platform Door Display System and Update Method Based on CAN Communication," describes a system where display units 21 are positioned above (for full-height doors) or to the side (for half-height doors) of the platform door, with one display unit 21 for each pair of platform doors. The display system 2, the platform door management host 1, and the platform door control system are all connected to a redundant CAN bus. The platform door management host 1 sends messages containing train times and departure stations; the display system 2 receives, parses, and displays the train information. The platform door management host 1 also sends messages for opening, closing, and aligning / isolating train doors; both the platform door control system and the display system 2 receive these messages. The platform door control system executes the corresponding actions, while the display system 2 displays the current platform door status and passenger reminders. The platform door control system does not need to directly manage the display system 2, improving its execution efficiency. The display system 2 can also display specific fault information based on received messages, reminding passengers to pay attention to safety. When no train is entering the station, the platform door management host 1 can send promotional messages; the display system 2 parses the messages and plays the corresponding promotional content. When the displayed content needs to be updated or the program of display system 2 itself needs to be replaced, the platform screen door management host 1 can send the updated content to display system 2 via the CAN bus during non-metro operating hours. This invention has the following advantages: wide information coverage, ensuring that passengers in front of each pair of platform screen doors can obtain rich information; centralized management, with the updated content and program of display system 2 managed uniformly through the platform screen door management host 1; high information synchronization efficiency, as each node device connected to the CAN bus can exchange messages, improving equipment operating efficiency; and diversified display content, not limited to train information, platform screen door status, and promotional information, offering flexibility in expanding and updating the displayed content.
[0060] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0061] In the description of this invention, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0062] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0063] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0064] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.
Claims
1. A method for displaying subway platform doors based on CAN communication, characterized in that, Include: The platform door management host and the display unit in the display system exchange message commands via a CAN bus. The message commands include identifiers and data fields. The identifier includes: Device type, used to identify the sender of this message instruction; Message type, used to identify different message types; The display unit number is used to identify the display unit that receives or sends the message instruction; The data field is used to store the specific message content.
2. The subway platform door display method based on CAN communication as described in claim 1, characterized in that, The message instruction includes a first message instruction sent by the platform door management host to the display unit, which instructs the display unit to display or update according to the first message instruction; In the first message instruction: The device type is identified as the platform door management host; The message types include: display information and update information.
3. The subway platform door display method based on CAN communication as described in claim 2, characterized in that, If the display unit number in the first message instruction is set to a broadcast address, then the platform door management host sends the first message instruction to all the display units.
4. The subway platform door display method based on CAN communication as described in claim 2, characterized in that, If the display unit number in the first message instruction is set to the display unit number value of a certain display unit, then the platform door management host sends the first message instruction individually to the display unit with the display unit number value.
5. The subway platform door display method based on CAN communication as described in claim 2, characterized in that, The displayed information includes: vehicle information, platform door information, passenger information, and promotional information.
6. The subway platform door display method based on CAN communication as described in claim 5, characterized in that, The first message instruction includes a display message instruction. When the message type in the display message instruction is set to display information, the display stage begins, and the platform door management host sends a display message instruction carrying display information to the display unit.
7. The subway platform door display method based on CAN communication as described in claim 2, characterized in that, The update information includes: updating the display content and updating the display program.
8. The subway platform door display method based on CAN communication as described in claim 7, characterized in that, The first message instruction includes an update message instruction. When the message type in the update message instruction is set to update information, the update phase begins, and the platform door management host sends an update message instruction carrying update information to the display unit.
9. The subway platform door display method based on CAN communication as described in claim 8, characterized in that, The identifier of the update message instruction also includes: key information used to identify different update message instructions in the update phase; The update message instruction includes: a first update message instruction, a second update message instruction, and a third update message instruction; The update methods include: The platform door management host sends a first update message instruction to the display unit. In the first update message instruction, the key information is set as first type of information, the data field contains a length flag, and the remaining bytes in the data field fill the total length of the specific content of the update information in the second update message instruction. The platform door management host sequentially sends multiple second update message instructions to the display unit. In the second update message instructions, the key information is set as first type information, and the data field is filled with the specific content of the update information. The platform door management host sends a third update message instruction to the display unit. In the third update message instruction, the key information is set to the second type of information, and the data field is filled with an update check value.
10. The subway platform door display method based on CAN communication as described in claim 9, characterized in that, The method for calculating the check value includes: calculating the check value using the CRC algorithm based on the binary data of the complete update information. The platform door management host uses the method described above to calculate the update check value and fills it into the data field of the third update message instruction. After receiving the update message instruction, the display unit calculates the received verification value using the method for calculating the verification value, compares the received verification value with the update verification value, and if they match, the display unit stores the received update information.
11. The subway platform door display method based on CAN communication as described in claim 6 or 7, characterized in that, The identifier also includes a display content ID number, which is used to identify the content that needs to be displayed or updated by the display unit. The display unit displays or updates the corresponding content according to the received display content ID number.
12. The subway platform door display method based on CAN communication as described in claim 1, characterized in that, The message instruction includes a second message instruction sent by the display unit to the platform door management host, used to report the status of the display unit to the platform door management host; In the second message instruction: The device type is identified as the display unit; The message type includes: the status information of the display unit; The display unit number is set to the display unit number value of the display unit that sent the second message instruction.
13. The subway platform door display method based on CAN communication as described in claim 12, characterized in that, The display unit periodically sends the second message instruction to the platform door management host.
14. The subway platform door display method based on CAN communication as described in claim 10, characterized in that, The message instruction includes a verification success message sent by the display unit to the platform door management host. If the verification by the display unit is successful, the display unit sends the verification success message to the platform door management host. The verification success message includes: The device type is identified as the display unit; The message type is the same as the message type in the first message instruction received by the display unit; The display unit number is set to the display unit number value of the display unit that sent the verification success message; The key information is set as the second type of information; The data field is populated with an update check value.
15. The subway platform door display method based on CAN communication as described in claim 10, characterized in that, The message instruction includes a verification failure message sent by the display unit to the platform door management host. If the verification by the display unit is inconsistent, the display unit sends a verification failure message to the platform door management host. In the verification failure message: The device type is identified as the display unit; The message type is the same as the message type in the first message instruction received by the display unit; The display unit number is set to the display unit number value of the display unit that sent the verification success message; The key information is set as the second type of information; The data field is filled with a verification failure flag.
16. The subway platform door display method based on CAN communication as described in claim 15, characterized in that, After receiving the verification failure message, the platform door management host re-sends the update message instruction to the display unit using the update method.
17. The subway platform door display method based on CAN communication as described in claim 1, characterized in that, The identifier in the message instruction also includes a message check value, used to ensure the data correctness of the message instruction.
18. A subway platform door display system based on CAN communication, used to implement the subway platform door display method based on CAN communication as described in any one of claims 1-17, characterized in that, Includes: a platform screen door management host and display system connected via a CAN bus; The display system includes multiple display units, each of which is located at a platform door, and the number of display units is the same as the number of platform doors. The platform door management host is used to send display message instructions carrying display information and update message instructions carrying update information to the display unit; The display unit is used to send a second message instruction carrying the status information of the display unit to the platform door management host.
19. The subway platform door display system based on CAN communication as described in claim 18, characterized in that, The platform screen door is a full-height door, and the display unit is fixedly installed on the top of the full-height door.
20. The subway platform door display system based on CAN communication as described in claim 18, characterized in that, The platform screen door is a half-height door, and the display unit is fixedly installed on the side of the half-height door.
21. The subway platform door display system based on CAN communication as described in claim 18, characterized in that, The CAN bus has two redundant lines and uses twisted-pair shielded wire for connection, with a communication rate of 125Kbps.
22. The subway platform door display system based on CAN communication as described in claim 18, characterized in that, The display unit includes: a controller, and a display screen and a memory connected to the controller; The memory includes a first memory and a second memory. The first memory is used to store the received display content, and the second memory is used to store the received application program.
23. The subway platform door display system based on CAN communication as described in claim 18, characterized in that, Each of the display units has a unique display unit number.