Automotive diagnostic communication link protocol switching circuit and control method

Abstract

The application relates to a car diagnosis communication link protocol switching circuit and a control method. The switching circuit comprises a host computer, a communication protocol transceiver module, a parallel structure switching module, a total and partial structure switching module and an OBD connector. The second data end of the communication protocol transceiver module is connected with the corresponding communication signal input end of the parallel structure switching module. The logic signal input end of the parallel structure switching module is connected with the first logic signal output end of the host computer. The communication signal output end of the parallel structure switching module is connected with the communication signal input end of the total and partial structure switching module. The communication signal output end of the total and partial structure switching module is connected with the plurality of communication pins of the OBD connector. The logic signal input end of the total and partial structure switching module is connected with the second logic signal output end of the host computer. The application can adapt to the application scene that the diagnosis communication pin position is uncertain in different car types, and significantly improves the flexibility and universality of the diagnosis link switching.

Description

Technical Field

[0001] This invention relates to the technical field of automotive diagnostic communication link protocol switching, and in particular to an automotive diagnostic communication link protocol switching circuit and control method. Background Technology

[0002] Currently, vehicle diagnostic tools communicate with the vehicle's OBD interface to read fault information and operational data from the vehicle's electronic control unit, thereby diagnosing the vehicle's operating status. Because different vehicle models use different diagnostic communication methods, various diagnostic communication link protocols have emerged in the automotive diagnostic field. Diagnostic tools need to switch between different communication protocols to adapt to the diagnostic needs of different vehicles.

[0003] In existing technologies, switching of diagnostic communication links is typically achieved through relays, discrete devices, or analog switches, and the link structure is mostly designed based on fixed OBD pin definitions. However, with the evolution of vehicle electronic architecture, more and more vehicle models no longer use the traditionally defined OBD pin combinations in diagnostic communication. For example, CAN 2.0 communication is no longer limited to pins 6 and 14, but may be distributed in other pin positions, resulting in greater uncertainty in the pin combinations for diagnostic communication.

[0004] Therefore, existing diagnostic link switching solutions based on fixed pin architecture cannot achieve flexible switching of any pin of the OBD interface. They usually require the addition of a large number of switching devices or redesign of the link structure, which leads to a significant increase in system complexity and cost, making it difficult to meet the diagnostic application requirements of multiple vehicle models and multiple pin combinations. Summary of the Invention

[0005] To address the problem that existing diagnostic communication link switching schemes, based on a fixed OBD pin architecture, are difficult to flexibly switch between multiple protocols on any pin of the OBD interface, this application provides an automotive diagnostic communication link protocol switching circuit and control method.

[0006] A vehicle diagnostic communication link protocol switching circuit includes a host computer, a communication protocol transceiver module, a parallel structure switching module, a main-to-branch structure switching module, and an OBD connector.

[0007] The first data communication terminal of the communication protocol transceiver module is connected to the data communication terminals of multiple components to be diagnosed that use different communication protocols. The second data terminal of the communication protocol transceiver module is connected to the corresponding communication signal input terminal of the parallel structure switching module. The logic signal input terminal of the parallel structure switching module is connected to the first logic signal output terminal of the host computer.

[0008] The communication signal output terminal of the parallel structure switching module is connected to the communication signal input terminal of the main-to-branch structure switching module. The host computer is used to select at most one target protocol from various communication protocols and build a first communication path through the parallel structure switching module, so that the communication signal corresponding to the target protocol is output to the main-to-branch structure switching module through the first communication path. The communication signals corresponding to the unselected communication protocols are electrically isolated from the signal output terminal of the parallel structure switching module.

[0009] The communication signal output terminal of the master-slave structure switching module is connected to multiple communication pins of the OBD connector, and the logic signal input terminal of the master-slave structure switching module is connected to the second logic signal output terminal of the host computer. The host computer is used to select the corresponding target pin among the various communication pins so that the communication signal can communicate through the target pin. The communication pins that are not selected are kept disconnected from the signal output terminal of the parallel structure switching module.

[0010] By adopting the above technical solution, and introducing a hierarchical switching architecture under unified control by the host computer into the diagnostic communication link, the selection of communication protocol and the selection of OBD physical pins are controlled independently. This makes diagnostic communication no longer dependent on fixed pin definitions, thereby enabling the establishment of flexible, controllable and non-interfering communication paths between various diagnostic communication protocols and multiple communication pins of the OBD interface. This effectively solves the problem of difficulty in adapting when the positions of diagnostic communication pins for different vehicle models are uncertain.

[0011] Preferably, the parallel structure switching module includes at least one switching management chip. The switching management chip is provided with multiple sets of protocol transceiver ports and two bus output ports. The protocol transceiver ports include a CAN2 transceiver port, a single-wire CAN transceiver port, a K-line transceiver port, an L-line transceiver port, a PWM transceiver port, and a VPW transceiver port. The protocol transceiver ports are respectively connected to the data communication terminals of multiple components to be diagnosed that use different communication protocols. Both of the bus output ports are connected to the signal input terminals of the total-to-splitting structure switching module.

[0012] By adopting the above technical solution, the physical layer signals of multiple different diagnostic communication protocols are centrally connected to the parallel structure switching module, and the single target protocol is selected under unified control. This ensures that non-target protocols are electrically isolated from the subsequent links, thereby avoiding bus conflicts and signal interference caused by the simultaneous access of multiple protocols and ensuring the stability and uniqueness of the diagnostic communication process.

[0013] Preferably, when the communication protocol corresponding to the protocol transceiver port is a differential communication protocol, there are two protocol transceiver ports corresponding to the differential communication protocol, and they are respectively connected to the corresponding bus output ports so that the two bus output ports respectively carry the high-level signal and low-level signal of the differential communication protocol. When the communication protocol corresponding to the protocol transceiver port is a single-wire communication protocol, there is only one protocol transceiver port corresponding to the single-wire communication protocol, and it is connected to any bus output port.

[0014] By adopting the above technical solution, and by using different signal carrying methods for differential communication protocols and single-wire communication protocols, the high and low level signals of the differential protocol can be transmitted through independent channels, while the single-wire protocol signal occupies only a single channel. This allows for compatibility with multiple diagnostic communication protocols with different physical layer characteristics under the same switching structure, thereby improving the system's adaptability to changes in protocol types.

[0015] Preferably, the switching management chip is provided with a protocol selection control port, a first enable control port, and a built-in first management element. The first management element is connected to both the protocol selection control port and the enable control port. The first management element is used to select at most one set of protocol transceiver ports from multiple sets of protocol transceiver ports according to a preset logic truth table, and is used to control the switching management chip to be in an on or off state. The protocol selection control port includes a logic level A port and a logic level B port, both of which are connected to the host computer. Both the logic level A port and the logic level B port are connected to the built-in first management element of the switching management chip. Each protocol transceiver port is connected to the corresponding bus output port through a first switch conducting element. The enable signal output terminal of the first management element is connected to the controlled terminal of the first switch conducting element.

[0016] By adopting the above technical solution, and by introducing a protocol selection and enable control mechanism based on a logical truth table inside the switching management chip, the communication protocol switching process has clear logical judgment rules. When there is an abnormality or the conditions are not met, the communication path can be automatically blocked, and the corresponding path can be established when the conditions are met, thereby improving the reliability and security of diagnosing the communication switching process.

[0017] Preferably, the master-slave structure switching module includes a first structure switch unit and a second structure switch unit. The communication signal input terminal of the first structure switch unit is connected to one of the bus output ports, and the communication signal input terminal of the second structure switch unit is connected to another of the bus output ports. The logic signal input terminals of the first structure switch unit and the second structure switch unit are each connected to the second logic signal output terminal of the host computer. The communication signal output terminal of the first structure switch unit is provided with multiple first pin connection ports, and the communication signal output terminal of the second structure switch unit is provided with multiple second pin connection ports. The first pin connection ports and the second pin connection ports are paired up and connected to the corresponding communication pins through the common node after pairing up.

[0018] By adopting the above technical solution and introducing a master-slave structure switching method on the communication bus, communication signals from the parallel structure can be orderly distributed to multiple communication pins of the OBD interface, and differential communication requirements can be supported through paired structures. This achieves flexible mapping of multiple OBD pins without increasing complex wiring, and improves the adaptability of the diagnostic link under different pin combinations.

[0019] Preferably, both the first and second structural switch units have a built-in second management element. The first and second pin connection ports are connected to their respective bus output ports via second switch conduction elements. The controlled terminals of each second switch conduction element are connected to the enable signal output terminal of the second management element. The second management element has logic level ports A0, A1, A2, and A3, all connected to the host computer. The second management element also has a second enable control port for controlling the first and second structural switch units to be in an on or off state.

[0020] By adopting the above technical solution, and by introducing address-based logic control and independent enable mechanism in the overall structure, the communication signal is only physically connected when the target pin is explicitly selected and in an enabled state, while the other pins are always kept disconnected. This effectively avoids misconnection, parallel connection or transient interference, and ensures the controllability and electrical safety of the diagnostic communication path.

[0021] A control method for an automotive diagnostic communication link protocol switching circuit, comprising:

[0022] Obtain diagnostic requirement information for the component to be diagnosed, and determine the target protocol based on the diagnostic requirement information;

[0023] According to the target protocol, a corresponding protocol selection control signal and a first enable control signal are generated. The protocol selection control signal is used to control the parallel structure switching module to build a first communication path, and the first enable control signal is used to control the parallel structure switching module to be in the on state.

[0024] Based on the target protocol, obtain the communication pin configuration relationship of the corresponding OBD connector, and determine the corresponding target pin according to the communication pin configuration relationship;

[0025] Based on the target pin, a corresponding pin selection control signal and a second enable control signal are generated. The pin selection control signal is used to control the master-slave structure switching module to establish a second communication path, and the second enable control signal is used to control the master-slave structure switching module to be in the on state.

[0026] By adopting the above technical solution, the diagnostic communication process is divided into consecutive steps such as target protocol determination, communication path establishment, and target pin selection. This makes the switching process of the diagnostic link form a clear control flow, ensuring that there is a clear sequential relationship between communication protocol selection and physical pin mapping, thereby improving the overall coordination and execution stability of the diagnostic system in multi-protocol and multi-pin scenarios.

[0027] Preferably, the step of generating the corresponding protocol selection control signal and the first enable control signal according to the target protocol includes:

[0028] Map the target protocol to the corresponding protocol identifier information;

[0029] Real-time acquisition of abnormal status information;

[0030] The preset logic truth table is invoked, and based on the protocol identification information and abnormal state information, it is determined whether the corresponding first logic level combination can be identified.

[0031] If the corresponding first logic level combination cannot be determined, a first enable control signal is generated to control the parallel structure switching module to be in the off state.

[0032] If the corresponding first logic level combination can be determined, a first enable control signal is generated to control the parallel structure switching module to be in the on state, and a corresponding protocol selection control signal is generated based on the first logic level combination.

[0033] By adopting the above technical solution, and by introducing protocol identifier mapping, abnormal state judgment and logical truth table judgment mechanism in the protocol selection process, the protocol switching has the control capabilities of being determinable, blocking and recoverable. When the communication conditions are not met, the link establishment can be blocked in time, and the corresponding control signal can be generated again when the conditions are met, thereby reducing the impact of erroneous protocol selection on the diagnostic system.

[0034] Preferably, the step of obtaining the communication pin configuration relationship of the corresponding OBD connector based on the target protocol, and determining the corresponding target pin according to the communication pin configuration relationship, includes:

[0035] Based on the target protocol, the communication pin configuration relationship of the corresponding OBD connector is read from the pre-stored configuration relationship table;

[0036] Based on the communication pin configuration relationship, a set of candidate pins that meet the communication requirements of the target protocol is selected;

[0037] Based on the pin availability constraints under the current diagnostic status, the candidate pin set is evaluated to determine the corresponding target pin.

[0038] By adopting the above technical solution, a candidate pin set is generated based on the pre-stored communication pin configuration relationship after the protocol is determined, and the pin availability in the current diagnostic state is used for judgment. This makes the selection process of the target pin clear and avoids blindly establishing communication connections in the case of pin conflicts or unavailability, thereby improving the adaptability and reliability of diagnostic communication in complex vehicle interface environments.

[0039] Preferably, the step of generating a corresponding pin selection control signal and a second enable control signal based on the target pin includes:

[0040] Map the target pin to the corresponding pin identification information;

[0041] Real-time determination of whether communication prerequisites are met;

[0042] If the aforementioned communication prerequisites are not met, a second enable control signal is generated to control the total-to-subsidiary structure switching module to be in the off state.

[0043] If the aforementioned communication prerequisites are met, a second enable control signal is generated to control the main-branch structure switching module to be in the on state, and a preset logic truth table is called to determine the corresponding second logic level combination based on the pin identification information.

[0044] Based on the second logic level combination, a corresponding pin selection control signal is generated.

[0045] By adopting the above technical solution, under the premise that the target pin is determined, the pin information is converted into a logic level combination that can directly drive the switching structure, and the physical connection is enabled and controlled in combination with the communication preconditions. This ensures that the diagnostic communication link is established only when the execution conditions are met, effectively avoiding transient false connections and unexpected conduction during the switching process, and improving the safety and stability of the diagnostic communication execution phase.

[0046] In summary, this application includes at least one of the following beneficial technical effects:

[0047] This application introduces a layered and decoupled link switching structure into the automotive diagnostic communication link. This separates the selection of the communication protocol and the selection of the physical communication pins from the same switching level, and controls them independently through a parallel structure switching module and a master-slave structure switching module, respectively. First, the communication protocol transceiver module uniformly accesses the physical layer signals of multiple diagnostic communication protocols. Then, under the control of the host computer, the parallel structure switching module selects at most one target protocol from multiple communication protocols to establish the first communication path. This ensures that the unselected communication protocol is electrically isolated from the subsequent link, thus avoiding bus interference problems caused by multiple protocols accessing simultaneously. After the unique selection of the communication protocol is completed, the communication signal corresponding to the target protocol is not directly bound to a fixed OBD pin. Instead, the master-slave structure switching module, under the independent control of the host computer, switches the communication signal to the target communication pin of the OBD connector as needed according to a preset pin selection logic, while the remaining unselected communication pins remain disconnected. Through the synergistic effect of the two-stage switching structure described above, the selection of the communication protocol and the mapping relationship of the OBD pins are decoupled, thereby breaking through the structural limitations of traditional diagnostic links that rely on fixed pin definitions. This enables flexible switching of multiple diagnostic communication protocols between any communication pins on the OBD interface. This application not only adapts to application scenarios where the location of diagnostic communication pins is uncertain in different vehicle models, but also significantly improves the flexibility and versatility of diagnostic link switching while ensuring the uniqueness of the communication path and electrical isolation. It provides a clear and highly scalable solution for vehicle fault diagnosis across multiple vehicle models and protocols. Attached Figure Description

[0048] Figure 1 This is a flowchart of a vehicle diagnostic communication link protocol switching circuit according to one embodiment of this application.

[0049] Figure 2 This is a detailed flowchart of the parallel structure switching module and the main-branch structure switching module in a vehicle diagnostic communication link protocol switching circuit according to an embodiment of this application;

[0050] Figure 3 This is a schematic diagram of the specific circuit structure of the built-in chip of the parallel structure switching module in an embodiment of the automotive diagnostic communication link protocol switching circuit of this application;

[0051] Figure 4 This is a schematic diagram of the specific circuit structure of the built-in chip of the general-to-branch structure switching module in an embodiment of the automotive diagnostic communication link protocol switching circuit of this application;

[0052] Figure 5 This is a flowchart of a control method for a vehicle diagnostic communication link protocol switching circuit according to an embodiment of this application. Detailed Implementation

[0053] The present application will be further described in detail below with reference to the accompanying drawings.

[0054] In one embodiment, such as Figure 1 As shown, this application discloses an automotive diagnostic communication link protocol switching circuit, which includes a host computer, a communication protocol transceiver module, a parallel structure switching module, a main-to-branch structure switching module, and an OBD connector.

[0055] The first data communication terminal of the communication protocol transceiver module is connected to the data communication terminals of multiple components to be diagnosed that use different communication protocols. The second data terminal of the communication protocol transceiver module is connected to the corresponding communication signal input terminal of the parallel structure switching module. The logic signal input terminal of the parallel structure switching module is connected to the first logic signal output terminal of the host computer.

[0056] The communication signal output terminal of the parallel structure switching module is connected to the communication signal input terminal of the main-branch structure switching module. The host computer is used to select at most one target protocol from various communication protocols and build a first communication path through the parallel structure switching module. The communication signal corresponding to the target protocol is output to the main-branch structure switching module through the first communication path. The communication signals corresponding to the unselected communication protocols are electrically isolated from the signal output terminal of the parallel structure switching module.

[0057] The communication signal output terminal of the master-slave structure switching module is connected to multiple communication pins of the OBD connector, and the logic signal input terminal of the master-slave structure switching module is connected to the second logic signal output terminal of the host computer. The host computer is used to select the corresponding target pin among the various communication pins so that the communication signal can communicate through the target pin. The communication pins that are not selected are kept disconnected from the signal output terminal of the parallel structure switching module.

[0058] In this embodiment, an automotive diagnostic communication link protocol switching circuit is composed of a host computer, a communication protocol transceiver module, a parallel structure switching module, a main-to-branch structure switching module, and an OBD connector. The components form a clear hierarchical structure in terms of electrical connections and control logic. The communication protocol transceiver module is used to complete the physical layer transmission and reception of different diagnostic communication protocols. Its first data communication terminal is connected to the data communication terminal of the diagnostic component using different communication protocols, enabling diagnostic communication signals from different electronic control units of the vehicle to undergo level conversion, driving, and reception processing according to their respective protocol characteristics. The second data communication terminal of the communication protocol transceiver module is connected to the corresponding communication signal input terminal of the parallel structure switching module, thereby unifying the communication signals of multiple protocols into the subsequent switching structure. The parallel structure switching module is located between the communication protocol transceiver module and the master-slave structure switching module in terms of circuit structure. Its logic signal input terminal is connected to the first logic signal output terminal of the host computer, enabling the host computer to uniformly schedule and control different communication protocols according to the current diagnostic requirements. In actual operation, under the control of the host computer, the parallel structure switching module allows only one communication signal corresponding to the target protocol to be selected and output. The remaining unselected protocol communication signals are effectively isolated electrically, thereby avoiding interference caused by multiple diagnostic communication signals entering the downstream link at the protocol level. The communication signal selected by the parallel structure switching module is sent to the master-slave structure switching module through its communication signal output terminal. The communication signal input terminal of the master-slave structure switching module is connected one-to-one with the output terminal of the parallel structure switching module, so that the communication signal of the selected target protocol can be further distributed to the OBD connector side. The logic signal input terminal of the master-slave structure switching module is connected to the second logic signal output terminal of the host computer. This allows the host computer to independently control the mapping relationship between the communication signal and each communication pin of the OBD connector after completing the communication protocol selection. During operation, the master-slave structure switching module connects the communication signal to the target communication pin only according to the control signal given by the host computer. The remaining unselected communication pins are kept disconnected from the communication link, thereby avoiding misconnection of non-target pins or crosstalk. Through the above structural connection relationship and control logic, the host computer implements separate control at the protocol selection level and the pin mapping level, so that the determination of the communication protocol is no longer directly bound to the fixed definition of the OBD pins. This allows for flexible switching between the diagnostic communication protocol and any communication pin of the OBD interface while ensuring the uniqueness of the communication path and electrical isolation. This is suitable for vehicle application scenarios where the position of the diagnostic communication pins is uncertain or changes frequently.

[0059] Furthermore, such as Figure 2-3As shown, the parallel structure switching module includes at least one switching management chip. The switching management chip is equipped with multiple sets of protocol transceiver ports and two bus output ports. The protocol transceiver ports include CAN2 transceiver port, single-wire CAN transceiver port, K-line transceiver port, L-line transceiver port, PWM transceiver port and VPW transceiver port. The protocol transceiver ports are respectively connected to the data communication terminals of multiple components to be diagnosed using different communication protocols. Both bus output ports are connected to the signal input terminals of the main-branch structure switching module.

[0060] In this embodiment, the parallel structure switching module is used to establish a controllable protocol selection relationship among multiple diagnostic communication protocols, which can be implemented by at least one switching management chip. This switching management chip has multiple sets of protocol access ports, used to connect to the physical layer signals corresponding to different diagnostic communication protocols. For example, one set of protocol access ports can be used to receive communication signals from a CAN2.0 transceiver, and another set can be used to receive communication signals from single-wire diagnostic protocols such as single-wire CAN, K-line, or PWM. Each protocol access port is electrically connected to the output side of the corresponding protocol in the communication protocol transceiver module, thereby allowing diagnostic communication signals of different protocols to be independently introduced into the switching management chip. To facilitate unified processing at subsequent stages, the switching management chip also has two bus output ports, serving as a unified signal output interface for the parallel structure switching module. Both bus output ports are connected to the signal input terminals of the master-slave structure switching module, allowing the selected target protocol signal to be further transmitted to the pin switching structure.

[0061] In actual operation, the switching management chip does not simultaneously activate all protocol access ports. Instead, through its internal control logic, it allows only one set of ports from multiple protocol access ports to establish an electrical connection with the bus output port. For example, when the current diagnostic task requires the CAN2.0 communication protocol, the protocol access port corresponding to the CAN2.0 protocol is selected, and its communication signal is directed to the two bus output ports, while other protocol access ports remain disconnected from the bus output ports. When the diagnostic task switches to a single-wire communication protocol, only the protocol access port corresponding to that single-wire protocol is selected, and its communication signal is directed to one of the bus output ports, while the other bus output port remains idle. In this way, different diagnostic communication protocols are mutually exclusive before entering the subsequent circuitry, enabling the parallel structure switching module to play a role in centralized convergence and unique output at the protocol level.

[0062] Furthermore, such as Figure 3As shown, when the communication protocol corresponding to the protocol transceiver port is a differential communication protocol, there are two protocol transceiver ports corresponding to the differential communication protocol, and they are respectively connected to the corresponding bus output ports so that the two bus output ports carry the high-level signal and low-level signal of the differential communication protocol respectively. When the communication protocol corresponding to the protocol transceiver port is a single-wire communication protocol, there is only one protocol transceiver port corresponding to the single-wire communication protocol, and it is connected to any bus output port.

[0063] In this embodiment, to accommodate the differences in physical layer structure between different diagnostic communication protocols, the parallel structure switching module is designed differently for differential communication protocols and single-wire communication protocols in terms of protocol access port configuration. For differential communication protocols, such as CAN2.0 or PWM-type differential transmission protocols, the communication signal at the physical layer consists of a pair of mutually referenced signal lines, carrying high-level and low-level signals respectively. In this case, the switching management chip sets up two sets of independent protocol access ports for each differential communication protocol. One set of ports is used to receive the high-level component of the differential signal, and the other set of ports is used to receive the low-level component of the differential signal. These two sets of ports are electrically connected to the corresponding differential output terminals in the communication protocol transceiver module. When the above two sets of protocol access ports are selected, they establish a conduction relationship with the two bus output ports inside the switching management chip, so that the two signals of the differential communication protocol can be introduced into the subsequent circuit in pairs. This maintains the integrity and symmetry of the differential signal inside the parallel structure switching module, avoiding common-mode interference or signal distortion caused by signal merging or multiplexing.

[0064] For single-wire communication protocols, such as single-wire CAN, K-line, L-line, or VPW, the communication process relies solely on a single signal line to complete data transmission, eliminating the need for differential transmission of paired signals. In this case, the switching management chip sets up a corresponding protocol access port for each single-wire communication protocol. This protocol access port is electrically connected to the output of the corresponding single-wire protocol in the communication protocol transceiver module. When the single-wire communication protocol is selected, its protocol access port establishes a conduction relationship with only one of the bus output ports inside the switching management chip, while the other bus output port remains unconnected or idle. This avoids the unnecessary distribution of single-wire signals across multiple channels within the parallel structure switching module. Through this configuration, the parallel structure switching module can simultaneously support differential and single-wire communication protocols within the same hardware structure, without requiring separate switching channels for different protocol types.

[0065] Furthermore, such as Figure 3As shown, the switching management chip has a protocol selection control port, a first enable control port, and a built-in first management element. The first management element is connected to both the protocol selection control port and the enable control port. The first management element is used to select at most one set of protocol transceiver ports from multiple sets of protocol transceiver ports according to a preset logic truth table, and is used to control the switching management chip to be in an on or off state. The protocol selection control port includes a logic level A port and a logic level B port, both of which are connected to the host computer. Both logic level A port and logic level B port are connected to the built-in first management element of the switching management chip. Each protocol transceiver port is connected to the corresponding bus output port through a first switch conducting element. The enable signal output terminal of the first management element is connected to the controlled terminal of the first switch conducting element.

[0066] In this embodiment, the protocol selection and isolation control within the parallel structure switching module is implemented by the control structure within the switching management chip. This switching management chip is equipped with a protocol selection control port for receiving external control commands and a first enable control port for controlling the overall conduction state. The protocol selection control port can consist of multiple logic level input terminals, for example, two logic input ports, used to receive protocol selection encoding signals output from the host computer. These encoding signals correspond to different diagnostic communication protocols in different logic level combinations. The first enable control port receives an enable signal output from the host computer. This enable signal indicates whether a protocol-level communication path is currently allowed. When this port is in an invalid state, the switching management chip does not establish any conduction relationship between the protocol access port and the bus output port.

[0067] The switching management chip internally includes a first management element, which can be implemented using a logic decoding circuit, a state control circuit, or a combination thereof. This element is used to parse the logic levels input to the protocol selection control port. The first management element has a pre-configured logic truth table that defines the correspondence between different combinations of logic levels of the protocol selection control port and specific protocol access ports. During operation, when the first enable control port indicates that conduction is allowed, the first management element decodes the currently input protocol selection code according to the logic truth table, determining a unique target protocol access port from multiple sets of protocol access ports. When the first enable control port indicates that it is in the off state, the first management element ignores the input state of the protocol selection control port and forces all protocol access ports to be in a non-selected state.

[0068] Inside the switching management chip, a first switching element is provided between each set of protocol access ports and its corresponding bus output port. This first switching element can be implemented as an analog switch, a controlled transistor, or a field-effect transistor, and its controlled end is connected to the control output end of the first management element. After the first management element determines the target protocol access port, its control output end outputs a conduction control signal to the first switching element corresponding to the target protocol access port, causing the first switching element to enter the conducting state, thereby establishing an electrical connection between the target protocol access port and the corresponding bus output port. At the same time, the first management element keeps the first switching elements corresponding to other non-target protocol access ports in the closed state, so that the communication signals of non-target protocols are completely electrically isolated from the bus output ports.

[0069] Furthermore, such as Figure 2 and Figure 4 As shown, the master-slave structure switching module includes a first structure switch unit and a second structure switch unit. The communication signal input terminal of the first structure switch unit is connected to a bus output port, and the communication signal input terminal of the second structure switch unit is connected to another bus output port. The logic signal input terminals of the first structure switch unit and the second structure switch unit are both connected to the second logic signal output terminal of the host computer. The communication signal output terminal of the first structure switch unit is provided with multiple first pin connection ports, and the communication signal output terminal of the second structure switch unit is provided with multiple second pin connection ports. The first pin connection ports and the second pin connection ports are paired up and connected to the corresponding communication pins through the common node after pairing up.

[0070] In this embodiment, the master-slave structure switching module is used to controllably distribute communication signals among multiple physical pins of the OBD connector. Its overall structure consists of two sets of independent structural switching units. These two sets of structural switching units are functionally symmetrical and electrically carry different communication channels from the parallel structure switching module. Specifically, one set of structural switching units receives a first bus signal from the parallel structure switching module, and the other set receives a second bus signal from the same module. The two bus signals remain independent after entering the master-slave structure switching module, thus providing a unified structural basis for differential and single-wire communication. The input side of each set of structural switching units is connected to the corresponding bus output channel of the parallel structure switching module via wiring, while its output side leads out multiple pin connection channels for selectively connecting to various communication pins of the OBD connector.

[0071] In terms of structural design, each set of structural switch units has multiple pin connection ports on its output side. These pin connection ports are connected to the communication pins in the OBD connector according to a predetermined pin mapping rule. To adapt to the application requirements of differential communication protocols, the pin connection ports of the two sets of structural switch units are designed in pairs in terms of layout and connection method. That is, each pin connection port in the first structural switch unit is paired with a corresponding pin connection port in the second structural switch unit. These paired ports are electrically converged to the same OBD communication pin node. Through this paired structure, when the system needs to establish a differential communication link, the two communication signals from the two sets of structural switch units can be synchronously mapped to two different OBD communication pins through their corresponding pair of pin connection ports, thereby forming a complete differential signal channel. When the system needs to establish a single-line communication link, only the pin connection port corresponding to one set of structural switch units is activated, while the pin connection port of the other set of structural switch units remains unconnected, thereby avoiding the simultaneous distribution of a single-line communication signal to multiple channels.

[0072] Furthermore, such as Figure 4 As shown, both the first and second structure switch units have a built-in second management element. The first and second pin connection ports are connected to their respective bus output ports through second switch conduction elements. The controlled terminals of each second switch conduction element are connected to the enable signal output terminal of the second management element. The second management element has logic level ports A0, A1, A2, and A3, which are all connected to the host computer. The second management element has a second enable control port for controlling the first and second structure switch units to be in the on or off state.

[0073] In this embodiment, to achieve precise selection and reliable disconnection of communication signals among multiple communication pins of the OBD connector, a second management element is further provided inside the main-to-branch structure switching module for unified control of pin-level switching behavior. The second management element can be implemented using an address decoding control circuit, state control logic, or a combination thereof. Its main function is to receive pin selection control information from the host computer and convert this control information into specific pin conduction control actions. In the actual circuit, the second management element has multiple logic control input terminals, such as four logic level input ports: A0, A1, A2, and A3. These logic level input ports are used to receive pin address encoding signals output by the host computer, and different logic level combinations correspond to different communication pin positions in the OBD connector.

[0074] In terms of structural connection, each pin connection port of the first and second structural switching units is connected to its respective bus input channel through a corresponding second switching conduction element. The second switching conduction element can be implemented using devices such as analog switches, electrically controlled transistors, or field-effect transistors, and its controlled terminal is uniformly connected to the control output terminal of the second management element. When the second management element receives the A0–A3 logic level input, it decodes the address code according to the preset logic truth relationship and determines the target pin channel that needs to establish a conduction relationship. During this process, only the second switching conduction element corresponding to the target pin is controlled to enter the conduction state, so that the communication signal from the parallel structural switching module is connected to the target OBD communication pin through the corresponding structural switching unit. The other second switching conduction elements corresponding to non-target pins remain in the off state, thereby achieving unique selection of the communication path at the pin level.

[0075] To enhance the controllability and safety of the pin switching process, the second management element also has an independent second enable control port for unified control of the on / off state of the master-slave structure switching module. When the second enable control port is not activated, the second management element controls all second switch conducting elements to be in the off state regardless of the A0–A3 input state, keeping the communication signal disconnected from the communication pins of the OBD connector, thereby avoiding misconnection during system power-on, control signal switching, or non-communication phases. When the second enable control port is activated, the second management element selectively activates the corresponding second switch conducting elements according to the current address encoding result of A0–A3, establishing an effective pin-level communication path.

[0076] like Figure 5 As shown, a control method for an automotive diagnostic communication link protocol switching circuit is provided. The control method includes:

[0077] S10. Obtain diagnostic requirement information for the component to be diagnosed, and determine the target protocol based on the diagnostic requirement information;

[0078] S20. According to the target protocol, generate the corresponding protocol selection control signal and the first enable control signal. The protocol selection control signal is used to control the parallel structure switching module to build the first communication path, and the first enable control signal is used to control the parallel structure switching module to be in the conducting state.

[0079] S30. Based on the target protocol, obtain the communication pin configuration relationship of the corresponding OBD connector, and determine the corresponding target pin according to the communication pin configuration relationship;

[0080] S40. Based on the target pin, generate the corresponding pin selection control signal and the second enable control signal. The pin selection control signal is used to control the main-to-branch structure switching module to build the second communication path, and the second enable control signal is used to control the main-to-branch structure switching module to be in the on state.

[0081] In this embodiment, the component to be diagnosed refers to an electronic control unit or a functional module with a diagnostic communication interface installed on the vehicle, such as an engine control unit, transmission control unit, body control module, or emission control-related module. This component typically establishes a diagnostic communication path with the OBD interface via the vehicle's internal bus. Diagnostic requirement information refers to control information describing the current diagnostic task objective. It can be generated by the host computer when entering the diagnostic process and specifically includes the type identifier of the component to be diagnosed, the current diagnostic stage, the type of data to be read, or communication method constraints. This diagnostic requirement information serves as the basis for subsequent communication strategy selection. The target protocol refers to the unique communication protocol selected from multiple diagnostic communication protocols supported by the system after analyzing the diagnostic requirement information, used to establish communication with the component to be diagnosed. This target protocol remains fixed within the same diagnostic cycle to avoid communication rule conflicts.

[0082] The protocol selection control signal is a control signal generated by the host computer according to the target protocol. In engineering implementation, it can be represented as a set of logic level codes used to indicate the position of the protocol channel to be selected within the parallel structure switching module. The first enable control signal is a control signal that cooperates with the protocol selection control signal. It is used to indicate whether the parallel structure switching module allows the establishment of a protocol-level communication path. When the first enable control signal is in an active state, the parallel structure switching module responds to the protocol selection control signal and performs a switching action. When the signal is in an inactive state, the parallel structure switching module keeps all protocol paths disconnected. The parallel structure switching module is a protocol-level switching unit located between the communication protocol transceiver module and the subsequent pin switching structure. Its function is to select only the communication signal corresponding to the target protocol from multiple diagnostic communication protocols and electrically isolate the communication signals of other unselected protocols, thereby forming a unique first communication path. The first communication path refers to the protocol-level communication path formed by the communication protocol transceiver channel corresponding to the target protocol after being selected by the parallel structure switching module. This communication path is used to transmit the communication signal of the target protocol to the subsequent circuit.

[0083] Communication pin configuration relationships refer to a pre-established set of data describing the correspondence between different diagnostic communication protocols and OBD connector communication pins. This configuration relationship can be stored in a host computer or control system in the form of tables, mapping rules, or parameterized data, reflecting the possible communication pin locations used by different protocols under different vehicle or interface specifications. The target pin refers to the OBD connector communication pin ultimately determined for actual communication, based on the aforementioned communication pin configuration relationships and the current diagnostic status, given a predetermined target protocol. This target pin remains unique within a diagnostic communication cycle to ensure a stable communication path.

[0084] The pin selection control signal is a control signal generated by the host computer based on the target pin. In engineering implementation, it can be represented as a set of addressable logic codes used to indicate the pin channel positions that need to be activated within the main-to-specific structure switching module. The second enable control signal is used to control whether the main-to-specific structure switching module allows the establishment of physical pin connections. When the second enable control signal is active, the main-to-specific structure switching module establishes the corresponding physical connection relationship based on the pin selection control signal. When the signal is inactive, the main-to-specific structure switching module keeps all pin paths disconnected. The main-to-specific structure switching module is a pin-level switching unit located between the parallel structure switching module and the OBD connector. Its function is to distribute communication signals from the first communication path to the target communication pins of the OBD connector as needed, and to ensure that other unselected pins do not participate in communication. The second communication path refers to the complete physical communication path formed between the target protocol signal output by the parallel structure switching module, after being mapped by the main-to-specific structure switching module, and the target pin. This second communication path is used to realize the actual data interaction between the diagnostic instrument and the device under diagnosis.

[0085] Furthermore, the step of generating the corresponding protocol selection control signal and the first enable control signal according to the target protocol includes:

[0086] S201. Map the target protocol to the corresponding protocol identifier information;

[0087] S202. Obtain abnormal status information in real time;

[0088] S203. Call the preset logic truth table, and determine whether the corresponding first logic level combination can be determined based on the protocol identification information and the abnormal state information.

[0089] S204. If the corresponding first logic level combination cannot be determined, a first enable control signal is generated to control the parallel structure switching module to be in the off state.

[0090] S205. If the corresponding first logic level combination can be determined, a first enable control signal is generated to control the parallel structure switching module to be in the on state, and a corresponding protocol selection control signal is generated based on the first logic level combination.

[0091] In this embodiment, the target protocol refers to a unique diagnostic communication protocol determined in the preceding diagnostic process for establishing communication with the component under test. This target protocol remains stable within the current diagnostic cycle and serves as the basis for protocol-level switching and control. Protocol identification information is the result of an engineered representation of the target protocol. It is not the protocol itself, but rather an abstract identifier used for internal switching logic within the control circuit. For example, different diagnostic communication protocols can be represented using numerical encoding, enumeration numbers, or logical indexes, enabling the control system to distinguish and process different protocols in a unified format. By mapping the target protocol to protocol identification information, it is possible to avoid directly processing complex protocol names or characteristics in subsequent control logic, thereby improving the versatility and implementability of the control logic.

[0092] Abnormal state information refers to a set of status information used during protocol switching and communication preparation to reflect whether the current system operating state meets the conditions for establishing a protocol-level communication path. This abnormal state information can originate from the status monitoring results inside the host computer, feedback signals from the communication module, or circuit-level detection signals. It is used to indicate whether there are situations in the system that do not allow protocol switching or communication establishment, such as incomplete initialization, unstable state during switching, or detection of abnormal operating conditions. In this step, abnormal state information participates as a constraint in subsequent logical judgments to prevent the forced establishment of a communication path under inappropriate system states.

[0093] A logic truth table is pre-defined control rule data used to define the control results corresponding to different protocol identification information under different system states. It can be implemented through table lookup, rule mapping, or fixed logical relationships. In engineering, this logic truth table describes the combined input conditions of protocol identification information and abnormal state information, as well as the control decision results to be output when the conditions are met or not. The first logic level combination refers to a set of logic level signals used to drive the parallel structure switching module, obtained by calling the logic truth table under preset conditions. This logic level combination typically consists of multiple logic signals and is used to clearly indicate the location of the protocol channel that needs to be selected within the parallel structure switching module.

[0094] When a valid first logic level combination cannot be determined from the logic truth table based on protocol identification information and abnormal state information, it indicates that the current system state does not meet the conditions for establishing a protocol-level communication path. In this case, the generated first enable control signal is used to control the parallel structure switching module to remain in the off state, ensuring that its internal protocol channels remain disconnected from subsequent circuits, thereby preventing the misselection of communication protocols under abnormal or unstable conditions. In this situation, the first enable control signal uniformly blocks the protocol-level communication path, ensuring the system is in a safe non-communication state.

[0095] When the corresponding first logic level combination can be determined through the logic truth table based on the protocol identification information and abnormal state information, it indicates that the current system state allows the establishment of a protocol-level communication path. At this time, the generated first enable control signal is used to control the parallel structure switching module to enter the conduction state, enabling it to respond to the protocol selection control signal and perform a switching action. The protocol selection control signal is a control signal generated based on the first logic level combination. In engineering implementation, it can be represented as a set of explicit logic level outputs, used to drive the switching conduction elements inside the parallel structure switching module, thereby selecting the communication channel corresponding to the target protocol from multiple diagnostic communication protocol channels and introducing the communication signal of the target protocol into the subsequent link.

[0096] Furthermore, the step of obtaining the communication pin configuration relationship of the corresponding OBD connector based on the target protocol, and determining the corresponding target pin based on the communication pin configuration relationship, includes:

[0097] S301. Based on the target protocol, read the communication pin configuration relationship of the corresponding OBD connector from the pre-stored configuration relationship table;

[0098] S302. Based on the communication pin configuration relationship, select a set of candidate pins that meet the communication requirements of the target protocol;

[0099] S303. Based on the pin availability constraints under the current diagnostic status, determine the candidate pin set and identify the corresponding target pin.

[0100] In this embodiment, the target protocol is the diagnostic communication protocol type determined in the preceding steps, used to define the physical layer communication conditions that must be met in the subsequent pin selection process. The pre-stored configuration table is a pin mapping data structure pre-established and stored in the host computer or control system. This configuration table describes the available OBD connector communication pin combinations for different diagnostic communication protocols under different vehicle or interface specifications. This configuration table can be derived from standard protocol specifications, OEM definitions, or historical diagnostic experience data, and is maintained in a parameterized form, enabling the system to quickly obtain pin configuration relationships matching the target protocol without manual intervention during operation.

[0101] The communication pin configuration relationship is a pin mapping result directly corresponding to the target protocol, read from the configuration relationship table. It clarifies the allowed OBD communication pin locations and their combinations at the physical connection level for the target protocol. This communication pin configuration relationship not only describes the numbering information of individual pins but also includes the pairing relationships of pins in differential or single-wire communication scenarios, signal direction attributes, and necessary electrical characteristic constraints, thus providing a complete engineering basis for subsequent pin selection. By introducing the communication pin configuration relationship, the pin selection process is kept consistent with the specific protocol characteristics, avoiding situations where pins are available at the protocol level but the physical connection is incompatible.

[0102] A candidate pin set refers to a set of OBD communication pins that meet the basic communication requirements of the target protocol, selected after analyzing the communication pin configuration relationships. All pins in this set have the potential to establish a communication path at the protocol specification level. This selection process eliminates pins incompatible with the target protocol, such as those that do not meet differential pairing requirements or lack corresponding signal functions, thereby narrowing the subsequent judgment range and improving the reliability and efficiency of pin selection. The generation of the candidate pin set allows the system to apply preliminary constraints based on protocol characteristics when faced with multiple possible pin combinations.

[0103] Pin availability constraints are status conditions used to reflect whether each communication pin is allowed to be occupied in the current diagnostic state. They can comprehensively consider factors such as the current diagnostic stage, existing communication connections, system resource occupancy status, and security control requirements. In engineering implementation, pin availability constraints can be reflected through status flags, locking mechanisms, or real-time detection results to prevent multiple communication tasks from contending for the same physical pin within the same time period. By applying these pin availability constraints to the candidate pin set, currently unavailable pin options can be further excluded while still meeting protocol requirements.

[0104] The target pin refers to the OBD connector communication pin ultimately determined for establishing the actual communication connection after considering the overall communication pin configuration relationships, the candidate pin set, and pin availability constraints under the current diagnostic status. This target pin maintains uniqueness and determinism within the current diagnostic cycle to ensure stable execution of subsequent pin-level switching and communication processes. Through this determination process, the selection of the target pin conforms to both the communication characteristics of the target protocol and the engineering feasibility requirements of the system's current operating state.

[0105] Furthermore, the step of generating the corresponding pin selection control signal and the second enable control signal based on the target pin includes:

[0106] S401. Map the target pin to the corresponding pin identification information;

[0107] S402. Real-time determination of whether the communication prerequisites are met;

[0108] S403. If the communication prerequisite is not met, a second enable control signal is generated to control the total-to-branch structure switching module to be in the off state.

[0109] S404. If the communication preconditions are met, a second enable control signal is generated to control the main-branch structure switching module to be in the on state, and the preset logic truth table is called to determine the corresponding second logic level combination according to the pin identification information.

[0110] S404. Generate the corresponding pin selection control signal based on the second logic level combination.

[0111] In this embodiment, the process of generating a pin selection control signal and a second enable control signal based on the target pin has a similar execution framework to the aforementioned protocol-level switching process in terms of overall control logic, but its control object and judgment criteria are significantly different. Compared to protocol-level gating control based on the target protocol, this step focuses on the actual landing position of the communication signal at the physical pin level. Its control granularity is further refined from protocol channel switching to the specific communication pin of the OBD connector. The pin selection control signal is no longer used to identify the protocol type, but rather to represent the position code of the target pin in the OBD connector, enabling the master-slave structure switching module to accurately map the communication signal to the corresponding physical pin.

[0112] The second enable control signal is functionally similar to the first enable control signal, both used to control whether the corresponding switching module allows the establishment of a communication path. However, its scope is limited to the pin-level switching structure. When the second enable control signal is in an invalid state, even if the target pin has been determined and the corresponding pin selection control signal has been generated, the master-slave structure switching module still keeps all pin paths disconnected to avoid establishing a physical connection prematurely if the pin status is not ready or the communication conditions are not met. When the second enable control signal is in an active state, the master-slave structure switching module performs the specific pin conduction operation according to the pin selection control signal. By making the enable control of pin-level switching independent of the protocol-level switching process, the system can further precisely control the communication path at the physical pin level after the protocol confirmation is completed, thereby reducing the risk of misconnection, short-term parallel connection, or pin conflict.

[0113] Specifically, the automotive diagnostic communication link protocol switching circuit is used to establish a controllable communication connection between multiple automotive diagnostic communication protocols and multiple communication pins of the OBD connector, so as to meet the communication requirements of different vehicle models and different diagnostic protocols. The switching circuit as a whole includes a communication protocol transceiver module, a parallel structure switching module, and a master-slave structure switching module, wherein each module is connected sequentially according to the signal processing order.

[0114] The communication protocol transceiver module provides physical layer transceiver functions for various automotive diagnostic communication protocols. It supports diagnostic communication protocols including CAN2.0, single-wire CAN, K-line, L-line, PWM, and VPW, and is suitable for diagnostic communication scenarios in 12V or 24V bus systems, depending on the vehicle's power supply system. For differential communication protocols, the transceiver module outputs both high-level and low-level signals; for single-wire communication protocols, it outputs only a single communication signal.

[0115] The parallel structure switching module is connected to the communication protocol transceiver module and is used to select a target protocol from multiple communication protocols and establish a first communication path. The parallel structure switching module internally has multiple protocol access channels and uses a controlled switch conduction structure to aggregate the communication signals corresponding to the target protocol to two bus output channels, one as the first bus output channel and the other as the second bus output channel. For differential communication protocols, the high-level signal is output through the first bus output channel, and the low-level signal is output through the second bus output channel; for single-wire communication protocols, the communication signal is output through only one bus output channel, while the other bus output channel remains closed.

[0116] The master-slave structure switching module is connected to the first bus output channel and the second bus output channel respectively, and is used to switch the communication signal from the parallel structure switching module to the target communication pin of the OBD connector as needed. The OBD connector includes multiple pins, wherein the number of pins used for communication is less than the total number of pins. The master-slave structure switching module can select the target pin among the communication pins and maintain electrical isolation between the unselected pins and the communication signal.

[0117] The working process of this embodiment will be explained below with reference to specific communication protocol examples.

[0118] When the automotive diagnostic tool communicates with the first and ninth communication pins of the OBD connector via the CAN2.0 communication protocol, the CAN high-level signal output by the communication protocol transceiver module is selected by the parallel structure switching module and enters the first bus output channel, while the CAN low-level signal is selected by the parallel structure switching module and enters the second bus output channel. Subsequently, the main-to-substructure switching module switches the communication signal in the first bus output channel to the first communication pin and the communication signal in the second bus output channel to the ninth communication pin, thereby establishing a complete differential communication path.

[0119] When the automotive diagnostic tool communicates with the seventh and fifteenth communication pins of the OBD connector via the K-line and L-line communication protocols, the K-line signal output by the communication protocol transceiver module is selected by the parallel structure switching module and enters the first bus output channel, while the L-line signal is selected by the parallel structure switching module and enters the second bus output channel. The main-to-branch structure switching module then switches the signal in the first bus output channel to the seventh communication pin and the signal in the second bus output channel to the fifteenth communication pin to achieve the communication connection of the corresponding protocol.

[0120] When the automotive diagnostic tool communicates with the second and tenth communication pins of the OBD connector via the PWM communication protocol, the PWM high-level signal output by the communication protocol transceiver module is selected by the parallel structure switching module and enters the first bus output channel, while the PWM low-level signal is selected by the parallel structure switching module and enters the second bus output channel. The main-to-branch structure switching module switches the two communication signals to the corresponding communication pins according to the control signal, thereby completing the PWM protocol communication connection.

[0121] When the vehicle diagnostic tool communicates with the first communication pin of the OBD connector via the single-wire CAN communication protocol, the single-wire CAN signal output by the communication protocol transceiver module is selected by the parallel structure switching module and enters the first bus output channel, while the second bus output channel remains closed. The main-to-branch structure switching module switches the communication signal in the first bus output channel to the first communication pin, thereby establishing a single-wire communication path.

[0122] When the automotive diagnostic tool communicates with the second communication pin of the OBD connector via the VPW communication protocol, the VPW signal output by the communication protocol transceiver module is selected by the parallel structure switching module and enters the first bus output channel, while the second bus output channel remains closed. The main-to-branch structure switching module switches the communication signal in the first bus output channel to the second communication pin, thereby realizing the VPW protocol communication connection.

[0123] Through the above structure and working method, this embodiment can flexibly switch between multiple diagnostic communication protocols and multiple communication pins of the OBD connector, and ensure that when any communication protocol is selected, the signal paths corresponding to other communication protocols remain closed, thereby avoiding signal interference and leakage risks. At the same time, it reduces the number of components, making the overall circuit structure compact and suitable for integrated applications.

[0124] The logic truth table for the parallel structure switching module is shown in the table below:

[0125]

[0126] The truth table for the total score structure switching module is shown in the table below:

[0127] Enable A3 A2 A1 A0 Non-conducting switch 0 X X X X No switch is conducting. 1 0 0 0 0 1 1 0 0 0 1 2 1 0 0 1 0 3 1 0 0 1 1 4 1 0 1 0 0 5 1 0 1 0 1 6 1 0 1 1 0 7 1 0 1 1 1 8 1 1 0 0 0 9 1 1 0 0 1 10 1 1 0 1 0 11 1 1 0 1 1 12 1 1 1 0 0 13 1 1 1 0 1 14 1 1 1 1 0 15 1 1 1 1 1 16

[0128] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A switching circuit for automotive diagnostic communication links, characterized in that, The automotive diagnostic communication link protocol switching circuit includes a host computer, a communication protocol transceiver module, a parallel structure switching module, a master-slave structure switching module, and an OBD connector. The first data communication terminal of the communication protocol transceiver module is connected to the data communication terminals of multiple components to be diagnosed that use different communication protocols. The second data terminal of the communication protocol transceiver module is connected to the corresponding communication signal input terminal of the parallel structure switching module. The logic signal input terminal of the parallel structure switching module is connected to the first logic signal output terminal of the host computer. The communication signal output terminal of the parallel structure switching module is connected to the communication signal input terminal of the main-to-branch structure switching module. The host computer is used to select at most one target protocol from various communication protocols and build a first communication path through the parallel structure switching module, so that the communication signal corresponding to the target protocol is output to the main-to-branch structure switching module through the first communication path. The communication signals corresponding to the unselected communication protocols are electrically isolated from the signal output terminal of the parallel structure switching module. The communication signal output terminal of the master-slave structure switching module is connected to multiple communication pins of the OBD connector, and the logic signal input terminal of the master-slave structure switching module is connected to the second logic signal output terminal of the host computer. The host computer is used to select the corresponding target pin among the various communication pins so that the communication signal can communicate through the target pin. The communication pins that are not selected are kept disconnected from the signal output terminal of the parallel structure switching module.

2. The automotive diagnostic communication link protocol switching circuit according to claim 1, characterized in that, The parallel structure switching module includes at least one switching management chip. The switching management chip is provided with multiple sets of protocol transceiver ports and two bus output ports. The protocol transceiver ports include a CAN2 transceiver port, a single-wire CAN transceiver port, a K-line transceiver port, an L-line transceiver port, a PWM transceiver port, and a VPW transceiver port. The protocol transceiver ports are respectively connected to the data communication terminals of multiple components to be diagnosed that use different communication protocols. Both of the bus output ports are connected to the signal input terminals of the total-to-splitting structure switching module.

3. The automotive diagnostic communication link protocol switching circuit according to claim 2, characterized in that, When the communication protocol corresponding to the protocol transceiver port is a differential communication protocol, there are two protocol transceiver ports corresponding to the differential communication protocol, and they are respectively connected to the corresponding bus output ports so that the two bus output ports respectively carry the high-level signal and low-level signal of the differential communication protocol. When the communication protocol corresponding to the protocol transceiver port is a single-wire communication protocol, there is only one protocol transceiver port corresponding to the single-wire communication protocol, and it is connected to any bus output port.

4. The automotive diagnostic communication link protocol switching circuit according to claim 3, characterized in that, The switching management chip is provided with a protocol selection control port, a first enable control port, and a built-in first management element. The first management element is connected to both the protocol selection control port and the enable control port. The first management element is used to select at most one set of protocol transceiver ports from multiple sets of protocol transceiver ports according to a preset logic truth table, and is used to control the switching management chip to be in an on or off state. The protocol selection control port includes a logic level A port and a logic level B port, both of which are connected to the host computer. Both the logic level A port and the logic level B port are connected to the built-in first management element of the switching management chip. Each protocol transceiver port is connected to the corresponding bus output port through a first switch conducting element. The enable signal output terminal of the first management element is connected to the controlled terminal of the first switch conducting element.

5. The automotive diagnostic communication link protocol switching circuit according to claim 2, characterized in that, The master-slave structure switching module includes a first structure switch unit and a second structure switch unit. The communication signal input terminal of the first structure switch unit is connected to one of the bus output ports, and the communication signal input terminal of the second structure switch unit is connected to another of the bus output ports. The logic signal input terminals of the first structure switch unit and the second structure switch unit are each connected to the second logic signal output terminal of the host computer. The communication signal output terminal of the first structure switch unit is provided with multiple first pin connection ports, and the communication signal output terminal of the second structure switch unit is provided with multiple second pin connection ports. The first pin connection ports and the second pin connection ports are paired up and connected to the corresponding communication pins through the common node after pairing up.

6. The automotive diagnostic communication link protocol switching circuit according to claim 5, characterized in that, Both the first and second structural switch units have a built-in second management element. The first and second pin connection ports are connected to their respective bus output ports via second switch conduction elements. The controlled terminals of each second switch conduction element are connected to the enable signal output terminal of the second management element. The second management element has logic level ports A0, A1, A2, and A3, all connected to the host computer. The second management element also has a second enable control port for controlling the first and second structural switch units to be in an on or off state.

7. A control method for a vehicle diagnostic communication link protocol switching circuit, characterized in that, Using a vehicle diagnostic communication link protocol switching circuit as described in any one of claims 1-6, the control method includes: Obtain diagnostic requirement information for the component to be diagnosed, and determine the target protocol based on the diagnostic requirement information; According to the target protocol, a corresponding protocol selection control signal and a first enable control signal are generated. The protocol selection control signal is used to control the parallel structure switching module to build a first communication path, and the first enable control signal is used to control the parallel structure switching module to be in the on state. Based on the target protocol, obtain the communication pin configuration relationship of the corresponding OBD connector, and determine the corresponding target pin according to the communication pin configuration relationship; Based on the target pin, a corresponding pin selection control signal and a second enable control signal are generated. The pin selection control signal is used to control the master-slave structure switching module to establish a second communication path, and the second enable control signal is used to control the master-slave structure switching module to be in the on state.

8. The control method for a vehicle diagnostic communication link protocol switching circuit according to claim 7, characterized in that, The step of generating the corresponding protocol selection control signal and the first enable control signal according to the target protocol includes: Map the target protocol to the corresponding protocol identifier information; Real-time acquisition of abnormal status information; The preset logic truth table is invoked, and based on the protocol identification information and abnormal state information, it is determined whether the corresponding first logic level combination can be identified. If the corresponding first logic level combination cannot be determined, a first enable control signal is generated to control the parallel structure switching module to be in the off state. If the corresponding first logic level combination can be determined, a first enable control signal is generated to control the parallel structure switching module to be in the on state, and a corresponding protocol selection control signal is generated based on the first logic level combination.

9. The control method for a vehicle diagnostic communication link protocol switching circuit according to claim 7, characterized in that, The step of obtaining the communication pin configuration relationship of the corresponding OBD connector based on the target protocol, and determining the corresponding target pin according to the communication pin configuration relationship, includes: Based on the target protocol, the communication pin configuration relationship of the corresponding OBD connector is read from the pre-stored configuration relationship table; Based on the communication pin configuration relationship, a set of candidate pins that meet the communication requirements of the target protocol is selected; Based on the pin availability constraints under the current diagnostic status, the candidate pin set is evaluated to determine the corresponding target pin.

10. The control method for a vehicle diagnostic communication link protocol switching circuit according to claim 9, characterized in that, The step of generating a corresponding pin selection control signal and a second enable control signal based on the target pin includes: Map the target pin to the corresponding pin identification information; Real-time determination of whether communication prerequisites are met; If the aforementioned communication prerequisites are not met, a second enable control signal is generated to control the total-to-subsidiary structure switching module to be in the off state. If the aforementioned communication prerequisites are met, a second enable control signal is generated to control the main-branch structure switching module to be in the on state, and a preset logic truth table is called to determine the corresponding second logic level combination based on the pin identification information. Based on the second logic level combination, a corresponding pin selection control signal is generated.

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