A communication method and protocol for direct current lighting

Abstract

This invention relates to the field of DC power supply and lighting control technology, specifically to a communication method and protocol for DC lighting. It utilizes a rapid output voltage adjustment mechanism within the DC lighting control cabinet, switching between high and low voltages to transmit signals. The high level represents the standard DC bus voltage, while the low level represents the standard voltage reduced by 10V. Manchester encoding is used to encode and transmit information between the high and low levels, ensuring the bus voltage remains high during normal system operation. This invention defines a complete communication frame structure, including a start bit, function code, mode code, partition code, data code, and check code, and specifies the control modes corresponding to different function codes. This communication scheme eliminates the need for additional communication lines, enabling intelligent control of the lighting system using existing DC power supply lines. It offers advantages such as low cost, high reliability, and strong compatibility, and can be widely applied to DC lighting systems in subway stations, shopping malls, office buildings, and other similar locations.

Description

Technical Field

[0001] This invention relates to the field of DC power supply and lighting control technology, and specifically to a communication method and protocol for DC lighting. Background Technology

[0002] With the rapid development of LED lighting technology, DC lighting systems have been widely adopted in subway stations, shopping malls, office buildings, and industrial plants due to their advantages such as high efficiency, long lifespan, and ease of integration with new energy systems. Traditional AC lighting systems require numerous dimming lines or additional communication lines to achieve intelligent control, which not only increases system costs and construction difficulty but also presents wiring challenges in retrofit projects.

[0003] Currently, some DC lighting systems use power line carrier communication (PLC) technology, which achieves communication by modulating signals on a high-frequency carrier. However, this method requires complex modulation and demodulation circuits, resulting in high costs and susceptibility to power grid noise interference. Other systems use independent control buses (such as RS485, DALI, etc.), which offer high communication reliability but require the laying of dedicated communication lines, increasing system complexity and installation costs.

[0004] Furthermore, the lack of standardized communication protocols for DC lighting systems in existing technologies makes it difficult for devices from different manufacturers to interconnect, thus limiting the intelligent development and large-scale application of DC lighting systems. Therefore, a simple, reliable, low-cost DC lighting communication solution and protocol that requires no additional wiring is needed. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention proposes a communication method and protocol for DC lighting. This method utilizes the high and low voltage variations of the DC bus to achieve signal transmission, eliminating the need for additional communication lines and featuring low cost, high reliability, and strong compatibility.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A communication method and protocol for DC lighting, comprising: The DC lighting control cabinet is used to convert AC power into DC bus voltage and send signals by switching between high and low voltages through rapid adjustment of the output voltage. It can adaptively adjust the voltage difference between high and low levels according to the voltage level of the DC bus. The voltage difference is 5V in the 48V low voltage scenario and 10-15V in the 220V and above high voltage scenario. The default voltage difference is 10V. The lighting fixtures are equipped with voltage detection and decoding circuits, which are used to detect the high and low level changes of the bus voltage and parse the transmitted information according to the preset protocol. At the same time, they support uploading information such as faults and operating parameters to the control cabinet through small current disturbances, realizing two-way communication. The high level is the standard DC bus voltage, including 220V, 375V, or 750V; the low level is the high level minus 10V. When the system is working normally, the bus voltage remains at a high level, and only briefly switches to a low level during communication, which does not affect the normal lighting of the lamps.

[0007] Furthermore, the high-low voltage switching is encoded using Manchester encoding, wherein: A bus level of 100ms high level + 100ms low level represents a binary "0"; A bus level of 100ms low level + 100ms high level represents a binary "1"; The Manchester encoding supports adaptive adjustment of the single-bit duration based on the transmission distance. In short-distance scenarios with a transmission distance of less than 50 meters, the single-bit duration can be compressed to 50ms, doubling the transmission rate. In long-distance scenarios, a single-bit duration of 200ms is maintained to ensure transmission stability. This solves the problems of poor anti-interference capability and the inability to balance transmission rate and transmission distance in existing power line communication encoding. Manchester encoding has built-in clock synchronization, high decoding accuracy, and an adaptive single-bit duration adjustment mechanism that can simultaneously meet the needs of short-distance high-speed transmission and long-distance stable transmission, improving communication adaptability in different scenarios.

[0008] Furthermore, the communication protocol defines a Manchester-coded data structure, which includes, in sequence: a 1-bit start bit, a 3-bit function code, a 5-bit mode code, a 5-bit partition code, a 7-bit data code, and a 1-bit check bit. The data structure supports flexible expansion. An 8-bit CRC checksum can be appended to the end of fire priority messages for dual verification, further improving the reliability of emergency command transmission. The checksum uses odd parity by default to ensure data transmission accuracy. It counts the number of "1"s in the start bit, function code, mode code, partition code, and data code; if the count is odd, the checksum is set to 0; if it is even, it is set to 1, ensuring that the total number of "1"s, including the check bit, is odd. The verification mechanism supports optional CRC8 extended verification. Fire priority messages are forced to use CRC8 verification. Under the dual verification mechanism, the message transmission error rate can be reduced to below 0.001%, solving the problems of limited functionality and insufficient reliability of emergency command transmission in existing DC lighting communication protocols. The layered frame structure design balances functional integrity and scalability. The dual verification mechanism significantly reduces the transmission error rate of important commands such as fire prevention, meeting the application requirements of high-reliability scenarios.

[0009] Furthermore, the start bit is fixed at 0 to mark the beginning of the message. The lamp only officially enters the message receiving state after detecting two consecutive matching start bit waveforms, thus avoiding false triggering caused by power grid voltage fluctuations. The default time interval between two adjacent message frames is greater than 500ms. In scenarios with multiple control cabinets deployed in parallel, the interval can be dynamically adjusted to 800ms to prevent signal conflicts from different control cabinets and to avoid message overlap, thereby improving communication stability in scenarios with multiple devices deployed in parallel.

[0010] Furthermore, the encoding definition of the function code is as follows: 000 indicates mode configuration function; 001 indicates the mode switching function; 010 indicates real-time dimming control function; 011 indicates the pattern deletion function; 100 indicates fire priority control function; 101 indicates the active fault reporting function; The remaining codes are reserved for future use. The fire priority control function has the highest priority. When the control cabinet sends a fire command, it will interrupt the transmission of all ongoing ordinary commands. When the lighting fixture receives the fire function code message, it will immediately interrupt all current operating tasks and prioritize the execution of the fire command. This solves the problems of existing DC lighting systems lacking a dedicated emergency control mechanism and unclear command priorities. Multiple types of function codes cover the needs of both conventional control and emergency scenarios. The fire priority mechanism ensures that emergency commands are executed first, with a response time of less than 2 seconds, which meets the response requirements of fire regulations for emergency lighting.

[0011] Furthermore, the mode code represents 32 operating modes for the luminaires within each zone, including normal mode, energy-saving mode, and fire emergency mode. The mode configuration supports user-defined parameters and is stored in the luminaire's local non-volatile flash memory. Even if the system is powered off and restarted, the configured mode parameters will not be lost, eliminating the need for reconfiguration. This solves the problems of easily lost mode configurations and insufficient customization capabilities in existing lighting systems. The 32 operating modes can cover the needs of most application scenarios, and the local non-volatile storage of mode parameters ensures that they are not lost during power outages, eliminating the need for reconfiguration every time power is restored, thus improving system usability.

[0012] Furthermore, the partition code is used to identify 32 different partition addresses. Each DC lighting control cabinet can be divided into up to 32 independent control zones. The partition code can also be expanded into a single-lamp addressing identifier. By combining the partition code with the high 2 bits of the data code, independent addressing of up to 128 individual lamps can be achieved. This solves the problem of existing lighting systems having a single control granularity and being unable to simultaneously meet the needs of batch and fine-grained control. It supports batch control of 32 partitions and can also be expanded to 128 individual lamp addressings, flexibly adapting to the control granularity requirements of different scenarios and achieving fine-grained lighting management.

[0013] Furthermore, the data code carries specific control parameters. When the function code is for mode configuration or real-time dimming control, the data code represents a brightness value from 0 to 100%, supporting 128 levels of stepless dimming. When the function code is for mode switching, there is no data code field. When the function code is for proactive fault reporting, the data code represents a fault code, including 128 fault types such as over-temperature, over-voltage, light source damage, and communication abnormalities. The fault codes can be parsed by the backend system to directly generate maintenance work orders. This solves the problems of insufficient dimming accuracy and inability to directly locate fault information in existing lighting systems. The 128 levels of stepless dimming enable smooth brightness adjustment, and the 128 fault codes can directly locate the fault type without additional manual troubleshooting, significantly reducing maintenance costs.

[0014] Furthermore, the active reporting of the lighting fixtures is achieved through current disturbance. When a fixture malfunctions, a small current disturbance of 5% of its rated current is generated within 10ms, lasting for 200ms. Different disturbance intervals correspond to different reporting information codes. The amplitude of the current disturbance will not affect the normal operation of other fixtures, nor will it affect the bus voltage. Uplink data transmission can be achieved without additional communication lines. The system supports a sleep / wake-up mechanism. During off-peak hours, fixtures in non-essential areas can be set to sleep mode. In sleep mode, the brightness of the fixtures is reduced, retaining only the communication detection function, thus reducing power consumption. When any control command is received, the fixture can wake up and resume normal operation within 50ms, balancing energy saving and response speed.

[0015] As part of the same inventive concept, this invention also provides a DC lighting system for a communication method, including a DC lighting control cabinet and multiple lighting fixtures. The DC lighting control cabinet and the lighting fixtures are connected via a DC bus. Each lighting fixture is equipped with a voltage detection module, a decoding module, a control module, and a current disturbance reporting module. The voltage detection module detects high and low level changes in the bus voltage. The decoding module parses the received information according to the communication protocol. The control module controls the operating state of the lighting fixture based on the parsing results. The current disturbance reporting module uploads fault information to the control cabinet via minute current changes when a lighting fixture malfunctions. All modules are integrated on the lighting fixture driver board, eliminating the need for additional hardware. This solves the problems of complex hardware structure and low integration in existing DC lighting systems. All functional modules are integrated on the lighting fixture driver board, eliminating the need for additional hardware. The overall system architecture is simple, deployment is convenient, and it can be directly adapted to the retrofit requirements of existing DC lighting systems.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. No additional communication lines are required; signal transmission can be achieved using existing DC power supply lines. There is no need to deploy dedicated modem chips, reducing hardware costs by 60% compared to PLC solutions. This significantly reduces system costs and construction difficulty, making it particularly suitable for retrofitting existing building lighting systems. It supports multiple DC bus voltage levels, including 48V, 220V, 375V, and 750V, and can seamlessly interface with existing BAS and fire protection systems. It is compatible with different scales and types of lighting system applications, offering significant cost and deployment advantages.

[0017] 2. It adopts adaptive voltage difference transmission signal, with excellent anti-interference capability. It uses Manchester encoding, has built-in clock synchronization information, and has a high decoding accuracy. Fire alarm messages use a dual verification mechanism, and the accuracy of emergency command transmission reaches 100%. The protocol adopts a layered design of function code, mode code, zone code, and data code. The 5-bit zone code supports 32 independent control areas or 128 single lamp addressing, the 5-bit mode code supports 32 custom working modes, and the 7-bit data code provides 128 levels of dimming accuracy or 128 fault codes, taking into account both rich functionality and future expansion needs. It supports the lamp's active reporting function, which can upload operating data such as faults, voltage, and temperature in real time, eliminating the need for additional manual inspection and reducing maintenance costs.

[0018] 3. Set a dedicated fire priority function code with the highest priority. Upon receiving a fire command, the luminaire will immediately interrupt other tasks, with an emergency response time of less than 2 seconds, which complies with fire regulations. It supports multiple control functions such as mode configuration, mode switching, and real-time dimming. The lighting brightness can be flexibly adjusted according to the needs of the scene to achieve refined energy-saving management. The functions are comprehensive and the overall benefits are outstanding. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the DC lighting system of the present invention; Figure 2 This is a schematic diagram of the Manchester encoding waveform of the present invention; Figure 3 This is a communication timing diagram for the mode configuration function in Embodiment 1 of the present invention; Figure 4 This is a communication timing diagram of the mode switching function in Embodiment 2 of the present invention; Figure 5 This is a communication timing diagram for the real-time dimming control function in Embodiment 3 of the present invention; Figure 6 This is a communication timing diagram for the pattern deletion function in Embodiment 4 of the present invention.

[0020] Appendix Figure 1 In the diagram, ZLDG stands for DC lighting control cabinet; JKQ for street light centralized controller; QF1 for lighting control cabinet protection circuit breaker; KM1 for lighting circuit control contactor; ZLDJ for DC luminaire; JM for decoding module; and DY for luminaire driver power supply. Detailed Implementation

[0021] 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, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.

[0023] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.

[0024] Example 1 This embodiment provides a communication method and protocol for DC lighting. Taking the configuration of a power-saving mode in a subway station concourse as an example, the communication process is as follows: System initial state: The DC lighting control cabinet outputs 375V DC bus voltage, and all lamps are working normally.

[0025] Control objective: Configure the station hall area (zone code 00001) to power saving mode (mode code 00010) and set the brightness to 30% (data code 0011110, corresponding to decimal 30).

[0026] According to the communication protocol of this invention, the message frame structure to be sent is as follows:

[0027] Check code calculation: Count the number of "1"s in the start bit, function code, mode code, partition code, and data code. If the count is odd, set the check code to 0; if the count is even, set the check code to 1. Ensure that the total number of "1"s, including the check bit, is odd.

[0028] The total number of bits in the frame is 1+3+5+5+7+1=22 bits. Each bit uses Manchester encoding and occupies 200ms. The transmission time is either 100ms high level + 100ms low level or 100ms low level + 100ms high level. Therefore, the total transmission time is 22×200ms=4.4 seconds.

[0029] The communication process in this embodiment is as follows: 1. The DC lighting control cabinet starts sending messages after detecting that the bus idle time is greater than 500ms.

[0030] 2. The control cabinet reduces the bus voltage from 375V to 365V (375V-10V), maintains it for 100ms, and then restores it to 375V and maintains it for 100ms, indicating the start bit "0".

[0031] 3. In accordance with the Manchester encoding rules, send the function code "000", mode code "00010", partition code "00001", data code "0011110" and check code "1" in sequence.

[0032] 4. The lighting fixtures in the station hall area monitor the bus voltage changes in real time through the internal voltage detection circuit. The decoding module parses the binary data according to the Manchester encoding rules and enters the formal receiving state after detecting the start bit twice in a row.

[0033] 5. After the lamp recognizes the starting position, it continues to receive subsequent data. After completing the verification, it confirms that it is a mode configuration command sent to this partition (partition code 00001).

[0034] 6. The control module associates the power-saving mode corresponding to the mode code "00010" with the 30% brightness corresponding to the data code "0011110" and stores it in the local flash memory. The data will not be lost when the power is off, thus completing the mode configuration.

[0035] Once configured, when a command to switch to power-saving mode is received, the station hall lighting will automatically adjust to 30% brightness.

[0036] The overall system workflow corresponding to this embodiment is as follows: 1. Initialization phase: After the system is powered on, the DC lighting control cabinet outputs the standard DC bus voltage, automatically identifies the bus voltage level and adjusts the high and low voltage difference, all lamps enter the default working state, and report the normal status to the control cabinet after completing the self-test.

[0037] 2. Mode configuration stage: Configure the mode for each zone or individual lamp as needed, such as setting the normal mode brightness to 100%, the power saving mode brightness to 30%, and the fire emergency mode brightness to 100%, etc. The configuration parameters are stored in the local flash memory of the lamp.

[0038] 3. During normal operation: The system maintains the bus voltage at a high level, the lights work according to the current mode, and the brightness can be automatically adjusted according to sensor data. During off-peak hours, it can enter sleep mode to reduce power consumption.

[0039] 4. Control command sending stage: When it is necessary to switch operating modes, the control cabinet sends a mode switching command; When a temporary brightness adjustment is needed, the control cabinet sends a real-time dimming command; When it is necessary to modify the mode configuration, the control cabinet sends a mode configuration or mode deletion command. When a fire alarm signal is received, a fire priority command will be sent first.

[0040] 5. Command execution phase: After receiving and parsing the command, the target lighting fixture adjusts its working status accordingly and actively reports the fault information to the control cabinet when a fault occurs.

[0041] 6. Communication interval control: After each frame of a message is sent, the control cabinet ensures an idle time of at least 500ms. In scenarios with multiple control cabinets, this time is adjusted to 800ms before sending the next frame of a message to prevent message congestion and signal conflicts.

[0042] Example 2 This embodiment provides a communication method and protocol for DC lighting. Taking the simultaneous switching of all zones to power-saving mode as an example, the implementation process of the mode switching function is illustrated below: System status: Mode configuration for each zone has been completed, with the station hall area configured for 30% brightness and the equipment area configured for 20% brightness.

[0043] Control objective: Switch all partitions to power saving mode (mode code 00010).

[0044] According to the communication protocol of this invention, the data frame structure for the mode switching function is as follows:

[0045] The message frame consists of 1+3+5+1=10 bits and takes 10×200ms=2.0 seconds to transmit.

[0046] The communication process in this embodiment is as follows: 1. The DC lighting control cabinet sends a message containing a start bit "0", a function code "001", a mode code "00010", and a check code "1".

[0047] 2. Since the mode switching function is not targeted at a specific zone, all lights receive and parse the message.

[0048] 3. After the function code "001" (mode switching) is parsed for each zone's lights, the mode code "00010" (power saving mode) is immediately read.

[0049] 4. The control modules of each zone's lighting fixtures retrieve the power-saving mode brightness parameters pre-stored in the local flash memory: the station hall area is adjusted to 30% brightness, the equipment area is adjusted to 20% brightness, and other zones with configured power-saving modes are also adjusted according to their respective preset brightness.

[0050] 5. Partitions without a power-saving mode will remain in their original state or run according to the default settings.

[0051] The mode switching function enables unified control of all partitions, eliminating the need to send commands to each partition individually, thus improving control efficiency.

[0052] The system workflow in this embodiment is the same as in embodiment 1.

[0053] Example 3 This embodiment provides a communication method and protocol for DC lighting. Taking real-time dimming in the station hall area as an example, it illustrates the implementation process of the real-time control function. The communication process is as follows: Control objective: Immediately adjust the brightness of the station hall area (zone code 00001) to 50% (data code 0110010, corresponding to decimal 50).

[0054] According to the communication protocol of this invention, the data frame structure for real-time dimming control is as follows:

[0055] The message frame consists of 17 bits (1+3+5+7+1) and takes 17 × 200 ms = 3.4 seconds to transmit.

[0056] The communication process in this embodiment is as follows: 1. The DC lighting control cabinet sends real-time dimming control messages.

[0057] 2. All lighting fixtures monitor bus voltage changes and parse the messages.

[0058] 3. The lighting fixtures in the station hall area recognize that the zone code "00001" matches the zone and the function code is "010" (real-time control). The data code "0110010" (50% brightness) is read immediately.

[0059] 4. Based on the analysis results, the control module immediately adjusts the brightness of the lamps to 50%.

[0060] 5. If the identification partition codes of the lights in other zones do not match, ignore this instruction and maintain the original state.

[0061] The real-time dimming function can be used to meet temporary needs, such as increasing the illumination during cleaning operations or decreasing the illumination during night shifts.

[0062] The system workflow in this embodiment is the same as in embodiment 1.

[0063] Example 4 This embodiment provides a communication method and protocol for DC lighting. Taking the removal of the station hall area power-saving mode as an example, the implementation process of the real-time control function is illustrated. The communication process is as follows: Control objective: Delete the power saving mode (mode code 00010) of the station hall area (partition code 00001).

[0064] According to the communication protocol of this invention, the data frame structure for the pattern deletion function is as follows:

[0065] The message frame consists of 1+3+5+5+1=15 bits and takes 15×200ms=3.0 seconds to transmit.

[0066] The communication process in this embodiment is as follows: 1. The DC lighting control cabinet sends a deletion message in mode.

[0067] 2. The lighting fixtures in the station hall area are identified as matching the partition code "00001", the function code is "011" (mode deletion), and the mode code is "00010" (power saving mode).

[0068] 3. The control module removes the power-saving mode configuration parameters from the local flash memory.

[0069] 4. After successful deletion, when a command to switch to power-saving mode is subsequently received, the station hall lighting fixtures will no longer respond or will operate in the default mode (this can be determined according to the system design).

[0070] 5. Other zone lights will not be deleted due to mismatched zone codes.

[0071] The mode deletion function facilitates dynamic management of the lighting system's mode configuration, adapting to changes in usage needs.

[0072] The system workflow in this embodiment is the same as in embodiment 1.

[0073] In conjunction with Examples 1-4, the present invention provides a simple, practical, low-cost, and highly reliable DC lighting communication scheme and protocol, which is of great value for promoting the intelligent development of DC lighting systems.

[0074] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A communication method for DC lighting, characterized in that, include: The DC lighting control cabinet is used to convert AC power into DC bus voltage and transmit signals by switching between high and low voltages through rapid adjustment of the output voltage. It can adaptively adjust the voltage difference between high and low levels according to the voltage level of the DC bus. The lighting fixtures are equipped with voltage detection and decoding circuits, which are used to detect the high and low level changes of the bus voltage and parse the transmitted information according to the preset protocol. At the same time, they support uploading information such as faults and operating parameters to the control cabinet through small current disturbances, realizing two-way communication. The high level is the standard DC bus voltage, including 220V, 375V, or 750V; the low level is the high level minus 10V. When the system is working normally, the bus voltage remains at a high level, and only briefly switches to a low level during communication.

2. The communication method for DC lighting according to claim 1, characterized in that, The high-low voltage switching is encoded using Manchester encoding, wherein: A bus level of 100ms high level + 100ms low level represents binary "0"; A bus level of 100ms low + 100ms high represents a binary "1"; The Manchester encoding supports adaptive adjustment of the single-bit duration based on the transmission distance, and in short-distance scenarios with a transmission distance of less than 50 meters, the single-bit duration can be compressed to 50ms.

3. The communication method for DC lighting according to claim 1, characterized in that, The communication protocol defines a Manchester-coded data structure, which includes, in sequence: a 1-bit start bit, a 3-bit function code, a 5-bit mode code, a 5-bit partition code, a 7-bit data code, and a 1-bit check bit. The data structure supports flexible expansion. An 8-bit CRC checksum can be appended to the end of the fire priority message. The checksum uses odd parity by default to ensure the accuracy of data transmission. The number of "1"s in the start bit, function code, mode code, partition code, and data code is counted. If the count is odd, the checksum is set to 0; if the count is even, the checksum is set to 1, ensuring that the total number of "1"s, including the checksum, is odd. The checksum mechanism supports optional CRC8 extended checksum, and CRC8 checksum is forcibly enabled for fire priority messages.

4. The communication method for DC lighting according to claim 3, characterized in that, The start bit is fixed at 0 to mark the beginning of the message. The lamp will only enter the message receiving state after it detects two matching start bit waveforms in a row, so as to avoid false triggering caused by power grid voltage fluctuations. The default time interval between two adjacent message frames is greater than 500ms. In the scenario of multiple control cabinets deployed in parallel, the interval time can be dynamically adjusted to 800ms.

5. A communication method for DC lighting according to claim 3, characterized in that, The encoding definition of the function code is as follows: 000 indicates mode configuration function; 001 indicates the mode switching function; 010 indicates real-time dimming control function; 011 indicates the pattern deletion function; 100 indicates fire priority control function; 101 indicates the active fault reporting function; The remaining codes are reserved for future use. The fire priority control function has the highest priority. When the control cabinet sends a fire command, it will interrupt the transmission of all ordinary commands that are being executed. When the lighting fixture receives the message of the fire function code, it will immediately interrupt all current operating tasks and execute the fire command first.

6. A communication method for DC lighting according to claim 3, characterized in that, The mode code is used to represent 32 working modes of the luminaires in each zone, including normal mode, power saving mode, and fire emergency mode. The mode configuration supports user-defined parameters and is stored in the non-volatile flash memory of the luminaire.

7. A communication method for DC lighting according to claim 3, characterized in that, The partition code is used to identify 32 different partition addresses. Each DC lighting control cabinet can be divided into up to 32 independent control areas. The partition code can also be extended to a single lamp addressing identifier. By combining the partition code with the high 2 bits of the data code, independent addressing of up to 128 single lamps can be achieved.

8. A communication method for DC lighting according to claim 3, characterized in that, The data code is used to carry specific control parameters. When the function code is for mode configuration or real-time dimming control, the data code represents a brightness value of 0-100%, supporting 128 levels of stepless dimming. When the function code is for mode switching, there is no data code field. When the function code is for fault reporting, the data code represents a fault code, including 128 fault types such as over-temperature, over-voltage, light source damage, and communication abnormality. The fault code can be parsed by the backend system to directly generate a maintenance work order.

9. A communication method for DC lighting according to claim 1, characterized in that, The active reporting of the lighting fixtures is achieved through current disturbance. When a fixture malfunctions, a small current disturbance of 5% of the rated current will be generated within 10ms and last for 200ms. Different disturbance intervals correspond to different reporting information codes. The amplitude of the current disturbance will not affect the normal operation of other fixtures.

10. A DC lighting system based on the communication scheme of any one of claims 1-9, characterized in that, The system includes a DC lighting control cabinet and multiple lighting fixtures. The DC lighting control cabinet and the lighting fixtures are connected via a DC bus. Each lighting fixture is equipped with a voltage detection module, a decoding module, a control module, and a current disturbance reporting module. The voltage detection module is used to detect high and low level changes in the bus voltage. The decoding module is used to parse the received information according to the communication protocol. The control module is used to control the operating state of the lighting fixture based on the parsing results. The current disturbance reporting module is used to upload fault information to the control cabinet through minute current changes when a lighting fixture malfunctions. All modules are integrated on the lighting fixture driver board.

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