A city rail transit air conditioning control unit

Abstract

The application discloses a kind of municipal rail transit air conditioner control units, including, CPU module, n extension module and display unit;CPU module and extension module are designed without backboard, are connected by soft wire, and power supply is provided for extension module and display unit;CPU module executes power-on self-test, and logic address is allocated for extension module, carries out data interaction with extension module by double CAN redundancy bus, executes logic operation after data acquisition, and issues control instruction;Extension module includes digital input / output module and analog input module, executes power-on self-test, acquires sensor signal or drive actuator, and data is fed back to CPU module;Display unit is connected CPU module by RS485 bus, and system state and acquisition variable are displayed in real time;The application adopts modular design to reduce the volume of control unit, and product can be quickly built according to the requirements of different vehicles to the system, reduce repeated development work and improve development efficiency.

Description

Technical Field

[0001] This invention relates to the field of rail transit control technology, and in particular to an air conditioning control unit for urban rail transit. Background Technology

[0002] The air conditioning control unit is a key component of the air conditioning system in urban rail transit vehicles. As the brain of the system, it automatically adjusts the refrigerant flow and temperature based on parameters such as temperature and humidity inside and outside the carriage to achieve optimal cooling or heating. Specifically, sensors installed inside the carriage monitor environmental parameters like temperature and humidity in real time and transmit the collected data to the control unit. The control unit analyzes and processes this data using algorithms to determine the optimal temperature setting, then activates the air conditioning equipment and adjusts the output of hot and cold air to quickly and effectively change the climate conditions inside the carriage. Simultaneously, the air duct system precisely controls the airflow direction and speed to ensure a uniform temperature distribution throughout the entire carriage.

[0003] As vehicle space becomes increasingly optimized, and different vehicles have varying requirements for the size and process control variables of their air conditioning control units, and because different vehicles use different interfaces for these control units, which are generally integrated boards, the control units suffer from high customization requirements and long development cycles. Changing the interface necessitates redesigning the board layout, and there is no flexibility in adding I / O acquisition and control variables. Summary of the Invention

[0004] This invention provides an air conditioning control unit for urban rail transit to overcome the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A municipal rail transit air conditioning control unit includes a CPU module, n expansion modules, and a display unit; The CPU module and the expansion module adopt a backplane-less design and are physically connected and transmit signals through a flexible flat cable. The CPU module is used to convert the external power supply into the internal working power supply and power the expansion module and the display unit. It performs power-on self-test, assigns logical addresses to the expansion module, interacts with the expansion module through a dual CAN redundant bus and performs logical operations, and sends control commands to the expansion module. The n expansion modules include at least one of digital input modules, digital output modules, and analog input modules, used to perform power-on self-test, acquire external sensor signals or drive external actuators, and feed the acquired data back to the CPU module via a bus. The display unit is used to receive and display in real time the system operating status and collected variables uploaded by the CPU module.

[0006] Furthermore, the power-on self-test steps of the CPU module include: Step 1: Test the power supply system: Test the main power supply voltage, core voltage and expansion module voltage. If overvoltage, undervoltage or fluctuation exceeds the preset threshold, lock the fault and terminate the startup. If no overvoltage, undervoltage or fluctuation exceeds the preset threshold, the power supply system is deemed to have passed the test and proceeds to the next self-test step. Step 2: After the power system test passes, test the clock system: Read the real-time value of the clock counter to determine whether the oscillation frequency of the main crystal oscillator and the timing accuracy of the RTC clock meet the preset value requirements. If a clock signal interruption, frequency offset exceeding the preset range, or RTC clock value not meeting the preset value requirements is detected, record the fault code and trigger a hardware alarm; if no clock signal interruption, frequency offset exceeding the preset range, or RTC clock value meeting the preset value requirements is detected, the clock system test is considered passed, and proceed to the next self-test step. Step 3: After the clock system test passes, perform memory test: Use a storage read / write test to verify the read / write speed, stability, and storage capacity of the Flash memory and RAM memory to check whether they meet the preset requirements; use a CRC check to verify the integrity of the configuration file. If any test fails, enter safe mode to troubleshoot; if all tests pass, proceed to the next self-test step. Step 4: After the memory test passes, perform communication interface testing: test the connectivity of the CAN interface, RS485 interface and Ethernet interface. The CAN interface adopts a dual-channel redundancy detection mechanism. If the test frame fails to be sent or no normal return signal is received, the corresponding communication interface is determined to be abnormal. Record the fault information and wait for further investigation.

[0007] Furthermore, the power-on self-test steps of the expansion module include: Step 1: Power supply test of the module: The operating voltage of the main control MCU, the power supply voltage of the digital I / O interface, and the power supply voltage of the analog circuit are continuously sampled by an analog-to-digital converter. The sampled analog voltage signals are converted into digital signals and compared with the preset rated voltage range. If any voltage exceeds the rated range, the power supply is marked as abnormal and the abnormal voltage value is recorded for manual troubleshooting. If all voltages are within the preset range, the power supply test is considered to have passed and the process proceeds to the next self-test step. Step 2: After the module power supply test passes, test the module clock: Use a timer to test the microcontroller system clock and peripheral clock frequency. If the timer count stops or the counting rate does not meet the threshold range, it indicates that there is a fault in the clock oscillation circuit, frequency divider circuit or drive circuit. Mark the clock fault and terminate the subsequent test. If no abnormality occurs, it is determined that the module clock test has passed and proceed to the next self-test step. Step 3: After the module clock detection is completed, test the expansion module channels: If it is a digital input module, test the level status of all input channels one by one, and use the detection circuit to determine whether there is a short circuit, open circuit, or level value that does not meet the requirements. If it is a digital output module, use the hardware readback circuit to perform closed-loop verification of the output status of each output channel. That is, after the module sends an output command, read back the actual output status of the channel and compare it with the preset output command to verify whether the output drive circuit can be used. If it is an analog input module, call the internal reference voltage source to perform basic calibration of the ADC acquisition module, and use the internal reference voltage source to verify the accuracy of the ADC. If the channel has a short circuit, open circuit, or level value that does not meet the requirements, or the actual output status is inconsistent with the preset output command or the deviation exceeds the threshold, mark the channel as faulty and stop the subsequent test; if no abnormality is found, it is determined that the expansion channel test is passed and proceed to the next self-test step. Step 4: After the expansion module channel test is completed, test the communication interface: check the CAN bus level status, terminating resistor connection status, and bus load status. If the CAN controller initialization fails, or if no bus response is found during the monitoring process, or if the bus level meets the preset value requirements, record the communication fault, mark the communication interface as abnormal, and stop reporting the self-test results, waiting for the CPU module's fault diagnosis instruction; if the CAN controller initialization is successful and the bus status is normal, the communication interface test is considered passed, and data transmission conditions are met; if CAN1 has a problem, data interaction with the CPU module is performed through CAN2. Step 5: After completing the above tests, the test results containing the fault markers are encapsulated into a standard data frame and sent to the CPU module.

[0008] Furthermore, assigning logical addresses to the expansion module, interacting with the expansion module via a dual CAN redundant bus for data exchange and logical operations, and issuing control commands to the expansion module, including: After power-on, the CPU module reads the stored expansion module configuration file, which contains the expansion module type, quantity, mounting order and expansion module parameter configuration. The CPU module assigns a unique logical address to each expansion module based on the read configuration file, and sends the assigned address information to the corresponding expansion module via a dual CAN redundant bus. The expansion module receives and saves the assigned address information, enters the communication ready state, and transmits the sensor data it collects to the central processing unit through the dual CAN redundant bus. The expansion module listens to two CAN buses at the same time. When the CAN1 main channel communication is abnormal, it automatically switches to the CAN2 backup channel for data transmission. The CPU module performs logical operations on the received sensor data. These logical operations include Boolean logic judgments on digital input data and PI operations or threshold comparisons on analog input data. The CPU module generates corresponding control commands based on the results of logical operations, and sends the control commands to the corresponding expansion modules through a dual CAN redundant bus. After receiving the control command, the expansion module executes the corresponding output control operation.

[0009] Furthermore, the flexible flat cable connection method is an FFC / FPC flat cable.

[0010] Furthermore, the communication method between the display unit and the CPU module is RS485.

[0011] Beneficial effects: This invention provides an air conditioning control unit for urban rail transit. It adopts a modular design to reduce the size of the control unit, allowing for rapid product development based on the system requirements of different vehicles, reducing repetitive development work and improving development efficiency. It also possesses the following advantages: 1. The control unit can be configured into different controllers to meet different needs, which improves the versatility of the controller; 2. The backplate-less design reduces the number of components and lowers costs. The use of flexible flat cable connections improves the product's usability in complex vibration environments. 3. The main CPU can automatically perform encoding and addressing; the module has a self-test function; and multiple bus methods are used internally, which improves the reliability of internal communication of the product. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1This invention provides a structural schematic diagram of an air conditioning control unit for urban rail transit. Figure 2 This is a block diagram of the centralized and distributed control of the present invention; Figure 3 This is a flowchart of the CPU module self-test process of the present invention; Figure 4 This is a flowchart of the self-test process for the extended module of this invention; Figure 5 This is a schematic diagram of the synchronization of the control unit system of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] This embodiment provides an air conditioning control unit for urban rail transit. The air conditioning control unit can perform centralized control and distributed control in different application scenarios, such as... Figure 2 As shown, Centralized control method: A single main air conditioning control unit directly collects external digital and analog signals for direct logic judgment and control. Its advantage lies in its shorter information transmission path and the elimination of complex coordination processes, often resulting in faster data processing speeds and simplified management and maintenance. This control method is suitable for scenarios with few collected and controlled variables and where installation space is not a constraint.

[0016] Distributed control method: This method consists of a main air conditioning control unit and slave control units. The main air conditioning control unit communicates with the slave control units via Ethernet. Data collected by the main control unit is integrated with data collected by the slave control units for unified processing. The slave control units are then controlled to output logic via communication. This control method is primarily used in scenarios with limited installation space and a large number of data acquisition and control variables. Its advantages include strong structural openness and adaptability, and good scalability. It allows for more flexible addition of new equipment or adjustment of existing interface configurations to adapt to constantly changing needs.

[0017] The structure of the air conditioning control unit for urban rail transit is as follows: Figure 1 As shown, it includes a CPU module, n expansion modules, and a display unit; The CPU module and the expansion module adopt a backplane-less design and are physically connected and transmit signals through a flexible flat cable. The CPU module is used to convert the external power supply into the internal working power supply and power the expansion module and the display unit. It performs power-on self-test, assigns logical addresses to the expansion module, interacts with the expansion module through a dual CAN redundant bus and performs logical operations, and sends control commands to the expansion module. Specifically, the air conditioning control unit mainly consists of an aluminum casing, a CPU module, a display unit, and expansion modules. The expansion modules are composed of I / O modules (DI, DO, AI, and other functions). The aluminum casing of the air conditioning control unit effectively improves heat dissipation for internal heat-generating components. It also enhances the electromagnetic compatibility of the control unit. The flexible flat cable connection method is FFC / FPC flat cable. The main air conditioning control unit and slave control unit adopt a modular design, which can be flexibly combined using CPU modules and expansion modules, thus enhancing adaptability and increasing product diversity. Modular design offers advantages such as improved production efficiency, shorter R&D cycles, enhanced product competitiveness, and promotion of sustainable development. As the core of the entire control system, the CPU module's system synchronization process directly determines the stability and reliability of the equipment's operation. After the equipment is powered on, the CPU module will complete initialization and multi-dimensional self-tests according to preset logic to ensure the coordinated operation of all system components. The internal self-test program is executed first after the system powers on; the steps of the power-on self-test are as follows: Figure 3 As shown, it includes: Step 1: Test the power supply system: Test the main power supply voltage, core voltage and expansion module voltage. If overvoltage, undervoltage or fluctuation exceeds the preset threshold, lock the fault and terminate the startup. If no overvoltage, undervoltage or fluctuation exceeds the preset threshold, the power supply system is deemed to have passed the test and proceeds to the next self-test step. Specifically, after the system powers on, the CPU module first initiates an internal power supply voltage detection process to ensure a stable and reliable power supply for the entire machine, laying the foundation for the normal operation of all subsequent modules. The detection scope mainly covers three key dimensions: main power supply voltage, core voltage, and I / O voltage. Among them, the main power supply voltage provides basic power to the entire CPU module and peripheral circuits, the core voltage directly affects the stable operation of the CPU core arithmetic unit, and the I / O voltage ensures the stability of signal transmission between the CPU and external interfaces. The CPU module samples each voltage in real time through a dedicated voltage detection chip or its internally integrated ADC (analog-to-digital converter), converts the analog voltage signal into a digital signal, and compares it with the preset rated voltage range. If any voltage is detected to be over-voltage, under-voltage, or fluctuating beyond the allowable range, the CPU will immediately enter a fault lockout state and terminate the system startup process to prevent damage to the CPU and other hardware modules due to abnormal voltage, ensuring the safety of the system equipment.

[0018] Step 2: After the power system test passes, test the clock system: Read the real-time value of the clock counter to determine whether the oscillation frequency of the main crystal oscillator and the timing accuracy of the RTC clock meet the preset value requirements. If a clock signal interruption, frequency offset exceeding the preset range, or RTC clock value not meeting the preset value requirements is detected, record the fault code and trigger a hardware alarm; if no clock signal interruption, frequency offset exceeding the preset range, or RTC clock value meeting the preset value requirements is detected, the clock system test is considered passed, and proceed to the next self-test step. Specifically, after the power system test passes, the CPU module immediately performs a comprehensive test on the system clock. As the "pulse" of the entire machine, the stability of the clock system directly determines the accuracy of CPU operations, data transmission, and the collaborative work of various modules. The test mainly includes two parts: the main crystal oscillator and the RTC (Real-Time Clock). The main crystal oscillator provides the core operating clock signal for the CPU, determining the CPU's processing speed and instruction execution rhythm. The RTC clock is responsible for providing a precise time base, ensuring system time synchronization and the normal execution of timed tasks. The CPU module reads the real-time value of the clock counter to determine whether the oscillation frequency of the main crystal oscillator and the timing accuracy of the RTC clock meet the preset value requirements. If a clock signal interruption, frequency offset exceeding the preset range, or RTC clock value not matching the required value is detected, the system will automatically record detailed fault information, including the fault type and occurrence time, and simultaneously trigger a hardware alarm mechanism to remind personnel to troubleshoot the fault promptly, avoiding problems such as erratic system instruction execution and data loss due to clock abnormalities.

[0019] Step 3: After the clock system test passes, perform memory test: Use a storage read / write test to verify the read / write speed, stability, and storage capacity of the Flash memory and RAM memory to check whether they meet the preset requirements; use a CRC check to verify the integrity of the configuration file. If any test fails, enter safe mode to troubleshoot; if all tests pass, proceed to the next self-test step. Specifically, after the clock system tests normal, the CPU module performs a comprehensive self-test on the onboard memory. As the core carrier for system data storage and instruction retrieval, the memory's operating status directly affects the system's normal operation. The self-test covers three aspects: Flash memory, RAM memory, and configuration file integrity. Flash memory stores system programs, firmware parameters, and expansion module configuration files. RAM memory temporarily stores data and instructions during system operation. Configuration files determine the system's operating parameters and the operating modes of expansion modules. During the test, the CPU module employs two core methods: CRC checksum and memory read / write test. CRC checksum verifies the integrity of stored data, preventing program malfunctions due to storage errors. The memory read / write test performs multiple read / write operations to check whether the read / write speed, stability, and storage capacity meet preset requirements. If any test fails, the system automatically enters a safe mode, retaining only basic core functions to prevent the fault from escalating and providing personnel with conditions to troubleshoot memory faults.

[0020] Step 4: After the memory test passes, perform communication interface testing: test the connectivity of the CAN interface, RS485 interface and Ethernet interface. The CAN interface uses a dual-channel redundancy detection mechanism. If the test frame fails to be sent or no normal return signal is received, the corresponding communication interface is determined to be abnormal. Record the fault information and wait for further investigation. Specifically, after the memory self-test passes, the CPU module initializes and configures various communication interfaces of the system and checks their communication status one by one. Communication interfaces are the key channels for data interaction between the CPU and external devices and expansion modules. The testing scope includes the CAN communication interface, RS485 communication interface, and Ethernet interface. The CAN communication interface is mainly used for short-distance, high-reliability data transmission in industrial scenarios; the RS485 communication interface is suitable for long-distance, multi-node data interaction; and the Ethernet interface is responsible for connecting the system to the network, supporting long-distance data transmission and remote control. During the testing process, the CPU module first initializes each communication interface, configuring parameters such as communication rate and data format. Then, by actively sending test frames, it checks the hardware operating status of the communication controller, signal transmission stability, and whether the interface driver is normal. If the test frame fails to be sent or no normal feedback signal is received, the corresponding communication interface is determined to be abnormal, the fault information is recorded, and further investigation is awaited to ensure the smooth operation of the system's data interaction channels. The expansion module uses dual redundant CAN channels for data interaction. After power-on, the CAN1 data link is established first. If the CAN1 communication fails, it automatically switches to CAN2. When CAN1 recovers, it switches back to the main channel. The expansion module listens to both CAN buses at the same time to ensure communication backup and fault tolerance, and improve the communication stability and reliability of the product. After the CPU module and expansion modules complete their self-tests, they establish communication, transmitting the expansion module's self-test information to the CPU module via communication. The CPU module compares the data with the number and type of backend modules and other information in the configuration file. After comparison, it synchronizes clock and other information to complete system synchronization. It then assigns logical addresses to the expansion modules, interacts with them via a dual CAN redundant bus for data exchange and logical operations, and sends control commands to the expansion modules. The steps are as follows: Figure 5 As shown, it includes: After power-on, the CPU module reads the stored expansion module configuration file, which contains the expansion module type, quantity, mounting order and expansion module parameter configuration. Specifically, the configuration file is the core basis for the system to identify and manage expansion modules. It is stored in the internal Flash memory area, and the CPU module accurately reads the expansion module configuration file from the Flash memory using dedicated read instructions. This configuration file contains key parameters required for system operation, including expansion module type, number of modules, module mounting order, and I / O parameter configuration. The expansion module type determines the drivers that the system needs to load, the number of modules and mounting order determine the communication address and collaborative working logic of the expansion modules, and the I / O parameter configuration specifies the working mode and voltage level standard of the expansion module's input and output ports. After reading the configuration file, the CPU module parses and verifies the file content. Once the parameters are confirmed to be correct, a complete expansion module identification list is established. This provides accurate parameter support for subsequent expansion module initialization, data interaction, and service scheduling, ensuring that the expansion modules can work properly with the CPU module. The CPU module assigns a unique logical address to each expansion module based on the read configuration file, and sends the assigned address information to the corresponding expansion module via a dual CAN redundant bus. Specifically, after comparing the configuration files, the CPU module assigns communication addresses to each module based on the identification results of the expansion modules. Once the addresses are assigned, the CPU module sends the address information to the expansion modules. Upon receiving the address information, the expansion modules save the addresses and enter the communication operation state. System information synchronization is crucial for ensuring the stable and accurate operation of the control system. This synchronization encompasses three key aspects: system clock synchronization, I / O sampling cycle synchronization, and data refresh cycle synchronization. After system startup, the CPU module, as the main control unit, continuously sends synchronization reference signals. Each expansion module receives these signals and precisely calibrates the deviation between its local clock and the system's master clock, ensuring a unified time base across the entire system. Simultaneously, it strictly aligns the I / O sampling cycles to avoid signal acquisition deviations caused by inconsistent sampling timing, ensuring the accuracy of data acquisition. It also synchronizes the data refresh cycle to ensure real-time data interaction between modules, preventing data delays and errors. After completing all synchronization calibration operations, each expansion module generates synchronization confirmation information containing its own module number, synchronization status, and calibration parameters. This information is sent to the CPU module using a fixed communication protocol, ensuring the CPU module clearly understands the synchronization status of each module. The CPU module verifies each received synchronization confirmation message, checking for synchronization anomalies. If any module fails to synchronize, it reissues the synchronization command until synchronization is complete. Once all extended modules have provided valid synchronization confirmation information, the system officially exits the initialization synchronization phase and enters normal operation mode, fully implementing various preset functions such as real-time control, data monitoring, and interaction. After information synchronization is completed, the expansion module receives and saves the assigned address information, enters the communication ready state, and transmits the sensor data it has collected to the central processing unit through the dual CAN redundant bus. The expansion module listens to two CAN buses at the same time. When the CAN1 main channel communication is abnormal, it automatically switches to the CAN2 backup channel for data transmission. The CPU module performs logical operations on the received sensor data. These logical operations include Boolean logic judgments on digital input data and PI operations or threshold comparisons on analog input data. The CPU module generates corresponding control commands based on the results of logical operations, and sends the control commands to the corresponding expansion modules through a dual CAN redundant bus. After receiving the control command, the expansion module executes the corresponding output control operation.

[0021] The n expansion modules include at least one of digital input modules, digital output modules, and analog input modules, used to perform power-on self-test, acquire external sensor signals or drive external actuators, and feed the acquired data back to the CPU module via a bus. Upon power-up, the expansion module immediately enters the internal initialization phase. After initialization, it automatically initiates a preset self-test program to comprehensively and systematically test all core hardware, peripherals, and communication links within the module. This ensures the module can function normally for subsequent operations. During the self-test, data from each stage is recorded in real time. After the entire self-test is completed, the integrated self-test results are sent to the CPU module in standard data frames. The CPU module then performs further diagnostic analysis, status display, and anomaly handling, providing a fundamental guarantee for the overall stable operation of the system. The complete self-test process of the expansion module includes the following six steps, each executed sequentially and interconnected to ensure thorough and comprehensive testing. The expansion module self-test process is as follows: Figure 4 As shown, it includes: Step 1: Power supply test of the module: The operating voltage of the main control MCU, the power supply voltage of the digital I / O interface, and the power supply voltage of the analog circuit are continuously sampled by an analog-to-digital converter. The sampled analog voltage signals are converted into digital signals and compared with the preset rated voltage range. If any voltage exceeds the rated range, the power supply is marked as abnormal and the abnormal voltage value is recorded for manual troubleshooting. If all voltages are within the preset range, the power supply test is considered to have passed and the process proceeds to the next self-test step. Specifically, module power supply testing is the first step in the self-test process. Its core purpose is to confirm the voltage stability and rationality of each power supply circuit within the expansion module, preventing misjudgments or hardware damage in subsequent testing stages due to power supply anomalies. The expansion module precisely tests three key internal power supply voltages: the operating power supply voltage of the main control MCU (microcontroller), the power supply voltage of the digital I / O interface, and the acquisition power supply voltage of the analog circuit. These three voltages directly determine the normal operation of the module's core components, interface circuits, and analog acquisition unit. During the testing process, the module continuously samples each voltage multiple times using its built-in ADC (analog-to-digital converter), converting the sampled analog voltage signals into digital signals and comparing them with preset rated voltage ranges. If any voltage exceeds the rated range (too high or too low), a power supply anomaly is immediately marked, and the abnormal voltage value is recorded for subsequent troubleshooting. If all voltages are within the preset range, the power supply test is considered passed, and the process proceeds to the next self-test step. Step 2: After the module power supply test passes, test the module clock: Use a timer to test the microcontroller system clock and peripheral clock frequency. If the timer count stops or the counting rate does not meet the threshold range, it indicates that there is a fault in the clock oscillation circuit, frequency divider circuit or drive circuit. Mark the clock fault and terminate the subsequent test. If no abnormality occurs, it is determined that the module clock test has passed and proceed to the next self-test step. Specifically, the module clock serves as the time reference for all operation instructions, data transmission, and peripheral control within the expansion module. Clock malfunctions can lead to serious problems such as erratic instruction execution, distorted data acquisition, and communication interruptions. Therefore, clock detection is crucial for ensuring the module's normal operation. The expansion module focuses on detecting whether its own microcontroller's system clock and peripheral clocks are functioning correctly. The detection principle involves activating an internal timer and monitoring the real-time changes in the timer counter register. If the clock is functioning correctly, the timer count will steadily increase at a preset frequency, and the counting period will meet the design standards. If the clock oscillation circuit, frequency divider circuit, or driver circuit malfunctions, the timer count will exhibit abnormal phenomena such as stalling, counting too fast, or too slow. In this case, the module will determine that the clock detection has failed, mark the clock as faulty, and stop subsequent irrelevant self-test steps to avoid invalid detection. Step 3: After the module clock detection is completed, test the expansion module channels: If it is a digital input module, test the level status of all input channels one by one, and use the detection circuit to determine whether there is a short circuit, open circuit, or level value that does not meet the requirements. If it is a digital output module, use the hardware readback circuit to perform closed-loop verification of the output status of each output channel. That is, after the module sends an output command, read back the actual output status of the channel and compare it with the preset output command to verify whether the output drive circuit can be used. If it is an analog input module, call the internal reference voltage source to perform basic calibration of the ADC acquisition module, and use the internal reference voltage source to verify the accuracy of the ADC. If the channel has a short circuit, open circuit, or level value that does not meet the requirements, or the actual output status is inconsistent with the preset output command or the deviation exceeds the threshold, mark the channel as faulty and stop the subsequent test; if no abnormality is found, it is determined that the expansion channel test is passed and proceed to the next self-test step. Specifically, the I / O channels are the core interfaces for data interaction between the expansion module and external devices. Their working status directly affects the module's input and output functions. Therefore, differentiated detection strategies must be adopted according to the type of expansion module (digital input, digital output, analog input) to ensure the normal functioning of each I / O channel. For digital input modules, the level status of all input channels is checked one by one. The built-in detection circuit determines whether there is a short circuit, open circuit, or level value that does not meet the requirements (such as unexplained high or low level), ensuring that external signals can be accurately transmitted to the module. For digital output modules, a hardware readback circuit is used to perform closed-loop verification of the output status of each output channel. That is, after the module sends an output command, the actual output status of the channel is immediately read back and compared with the preset output command to verify whether the output driver circuit can be used, avoiding the situation where the command is sent successfully but the actual output is abnormal. For analog input modules, an internal reference voltage source is called to perform basic calibration tests on the ADC acquisition module, initially verifying the accuracy of ADC acquisition and laying the foundation for subsequent accuracy verification of analog channels. During the analog channel calibration process, the module activates its internal reference voltage source, outputting a fixed, known-precision standard reference voltage. This voltage is used as the input signal to the ADC acquisition module. The ADC module continuously samples this reference voltage multiple times, averages the digital signals obtained from each sample, and calculates the actual sampled value. The actual sampled value is then compared with the standard digital value corresponding to the reference voltage, and the deviation between the two is calculated. If the deviation is within the system's preset error threshold, the analog channel calibration is considered successful, and the ADC acquisition module's accuracy meets the requirements. If the deviation exceeds the preset threshold, the analog channel is considered abnormal, the channel is marked as faulty, and the deviation data is recorded for subsequent maintenance and calibration. Step 4: After the expansion module channel test is completed, test the communication interface: check the CAN bus level status, terminating resistor connection status, and bus load status. If the CAN controller initialization fails, or if no bus response is found during the monitoring process, or if the bus level meets the preset value requirements, record the communication fault, mark the communication interface as abnormal, and stop reporting the self-test results, waiting for the CPU module's fault diagnosis instruction; if the CAN controller initialization is successful and the bus status is normal, the communication interface test is considered passed, and data transmission conditions are met; if CAN1 has a problem, data interaction with the CPU module is performed through CAN2. Specifically, the communication module consists of two parts, employing a redundant communication method. The two CAN communication physical links use completely isolated channels. The communication interface is the key link for data interaction between the expansion module and the CPU module, as well as other modules. CAN communication is a commonly used communication method for the expansion module, and its interface working status directly affects the stability of self-test result reporting and subsequent data transmission. During the testing process, the expansion module first initializes and configures the onboard CAN communication controller, loading preset communication parameters (such as baud rate, communication address, etc.). After initialization, it automatically enters the bus listening state to detect the CAN bus level status, the connection status of the terminating resistor, and whether the bus load is normal. If the CAN controller initialization fails, or if no bus response or abnormal bus level (such as bus short circuit or open circuit) is detected during listening, the module will immediately record the communication fault, mark the communication interface as abnormal, and stop reporting self-test results, waiting for the CPU module's troubleshooting instructions. If the CAN controller initialization is successful and the bus status is normal, the communication interface test is considered passed, and data transmission conditions are met. If CAN1 has a problem, CAN2 will perform data interaction with the CPU module. Step 5: After completing the above tests, the test results containing the fault markers are encapsulated into a standard data frame and sent to the CPU module. Specifically, self-test information generation is the final step in the entire self-test process. Its core function is to integrate and encapsulate the test results from the previous five steps into a standard self-test information data frame, facilitating CPU module recognition and processing. After completing all self-test steps, the extension module automatically starts the information integration program, collecting and organizing all test data to generate complete self-test information. This information covers the module's core identity information and test status information, specifically including the module model (used by the CPU module to identify the module type), module type (clearly indicating whether it is a digital input, output, or analog input module), module hardware version (facilitating subsequent version management and troubleshooting), self-test status (global self-test passed or abnormal; if abnormal, the abnormal step is marked), and the independent status of each IO channel (clearly indicating the working status of each channel). After all information is organized, the module encapsulates the self-test information into a standard data frame according to a preset communication protocol and sends it to the CPU module via the CAN communication interface, completing the entire power-on self-test process. The display unit is used to receive and display the system operating status and collected variables uploaded by the CPU module in real time. The communication method between the display unit and the CPU module is RS485.

[0022] In this invention, when using different expansion modules, the system can automatically encode and allocate addresses, while also performing module self-tests, thus improving the ease of use of the product. For example, the Type A urban area vehicle uses 3 DI and 2 AI modules. Before leaving the factory, the CPU module writes an expansion module configuration file, which includes the type and quantity of the expansion modules. Through system self-tests, information is synchronized with the expansion modules, completing communication between the CPU module and the expansion modules, thereby completing the data acquisition and related control work of the Type A urban area vehicle's air conditioning.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A municipal rail transit air conditioning control unit, characterized in that, It includes a CPU module, n expansion modules, and a display unit; The CPU module and the expansion module adopt a backplane-less design and are physically connected and transmit signals through a flexible flat cable. The CPU module is used to convert the external power supply into the internal working power supply and power the expansion module and the display unit. It performs power-on self-test, assigns logical addresses to the expansion module, interacts with the expansion module through a dual CAN redundant bus and performs logical operations, and sends control commands to the expansion module. The n expansion modules include at least one of digital input modules, digital output modules, and analog input modules, used to perform power-on self-test, acquire external sensor signals or drive external actuators, and feed the acquired data back to the CPU module via a bus. The display unit is used to receive and display in real time the system operating status and collected variables uploaded by the CPU module.

2. The urban rail transit air conditioning control unit according to claim 1, characterized in that, The power-on self-test steps of the CPU module include: Step 1: Test the power supply system: Test the main power supply voltage, core voltage and expansion module voltage. If overvoltage, undervoltage or fluctuation exceeds the preset threshold, lock the fault and terminate the startup. If no overvoltage, undervoltage or fluctuation exceeds the preset threshold, the power supply system is deemed to have passed the test and proceeds to the next self-test step. Step 2: After the power system test passes, test the clock system: Read the real-time value of the clock counter to determine whether the oscillation frequency of the main crystal oscillator and the timing accuracy of the RTC clock meet the preset value requirements. If a clock signal interruption, frequency offset exceeding the preset range, or RTC clock value not meeting the preset value requirements is detected, record the fault code and trigger a hardware alarm; if no clock signal interruption, frequency offset exceeding the preset range, or RTC clock value meeting the preset value requirements is detected, the clock system test is considered passed, and proceed to the next self-test step. Step 3: After the clock system test passes, perform memory test: Use a storage read / write test to verify the read / write speed, stability, and storage capacity of the Flash memory and RAM memory to check whether they meet the preset requirements; use a CRC check to verify the integrity of the configuration file. If any test fails, enter safe mode to troubleshoot; if all tests pass, proceed to the next self-test step. Step 4: After the memory test passes, perform communication interface testing: test the connectivity of the CAN interface, RS485 interface and Ethernet interface. The CAN interface adopts a dual-channel redundancy detection mechanism. If the test frame fails to be sent or no normal return signal is received, the corresponding communication interface is determined to be abnormal. Record the fault information and wait for further investigation.

3. The urban rail transit air conditioning control unit according to claim 1, characterized in that, The power-on self-test steps of the expansion module include: Step 1: Power supply test of the module: The operating voltage of the main control MCU, the power supply voltage of the digital I / O interface, and the power supply voltage of the analog circuit are continuously sampled by an analog-to-digital converter. The sampled analog voltage signals are converted into digital signals and compared with the preset rated voltage range. If any voltage exceeds the rated range, the power supply is marked as abnormal and the abnormal voltage value is recorded for manual troubleshooting. If all voltages are within the preset range, the power supply test is considered to have passed and the process proceeds to the next self-test step. Step 2: After the module power supply test passes, test the module clock: Use a timer to test the microcontroller system clock and peripheral clock frequency. If the timer count stops or the counting rate does not meet the threshold range, it indicates that there is a fault in the clock oscillation circuit, frequency divider circuit or drive circuit. Mark the clock fault and terminate the subsequent test. If no abnormality occurs, it is determined that the module clock test has passed and proceed to the next self-test step. Step 3: After the module clock detection is completed, test the expansion module channels: If it is a digital input module, test the level status of all input channels one by one, and use the detection circuit to determine whether there is a short circuit, open circuit, or level value that does not meet the requirements. If it is a digital output module, use the hardware readback circuit to perform closed-loop verification of the output status of each output channel. That is, after the module sends an output command, read back the actual output status of the channel and compare it with the preset output command to verify whether the output drive circuit can be used. If it is an analog input module, call the internal reference voltage source to perform basic calibration of the ADC acquisition module, and use the internal reference voltage source to verify the accuracy of the ADC. If the channel has a short circuit, open circuit, or level value that does not meet the requirements, or the actual output status is inconsistent with the preset output command or the deviation exceeds the threshold, mark the channel as faulty and stop the subsequent test; if no abnormality is found, it is determined that the expansion channel test is passed and proceed to the next self-test step. Step 4: After the expansion module channel test is completed, test the communication interface: check the CAN bus level status, terminating resistor connection status, and bus load status. If the CAN controller initialization fails, or if no bus response is found during the monitoring process, or if the bus level meets the preset value requirements, record the communication fault, mark the communication interface as abnormal, and stop reporting the self-test results, waiting for the CPU module's fault diagnosis instruction; if the CAN controller initialization is successful and the bus status is normal, the communication interface test is considered passed, and data transmission conditions are met; if CAN1 has a problem, data interaction with the CPU module is performed through CAN2. Step 5: After completing the above tests, the test results containing the fault markers are encapsulated into a standard data frame and sent to the CPU module.

4. The urban rail transit air conditioning control unit according to claim 1, characterized in that, Assigning logical addresses to the expansion module, interacting with the expansion module via a dual CAN redundant bus and performing logical operations, and issuing control commands to the expansion module, including: After power-on, the CPU module reads the stored expansion module configuration file, which contains the expansion module type, quantity, mounting order and expansion module parameter configuration. The CPU module assigns a unique logical address to each expansion module based on the read configuration file, and sends the assigned address information to the corresponding expansion module via a dual CAN redundant bus. The expansion module receives and saves the assigned address information, enters the communication ready state, and transmits the sensor data it collects to the central processing unit through the dual CAN redundant bus. The expansion module listens to two CAN buses at the same time. When the CAN1 main channel communication is abnormal, it automatically switches to the CAN2 backup channel for data transmission. The CPU module performs logical operations on the received sensor data. These logical operations include Boolean logic judgments on digital input data and PI operations or threshold comparisons on analog input data. The CPU module generates corresponding control commands based on the results of logical operations, and sends the control commands to the corresponding expansion modules through a dual CAN redundant bus. After receiving the control command, the expansion module executes the corresponding output control operation.

5. A municipal rail transit air conditioning control unit according to claim 1, characterized in that, The flexible flat cable connection method is FFC / FPC flat cable.

6. A municipal rail transit air conditioning control unit according to claim 1, characterized in that, The display unit communicates with the CPU module via RS485.

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