Automobile diagnosis communication link protocol switching circuit and control method

Abstract

The invention relates to an automobile diagnosis communication link protocol switching circuit and a control method. The protocol switching circuit comprises an upper computer, a communication protocol receiving and transmitting module, a parallel structure switching module, a total-branch structure switching module and an OBD connector. A second data end of the communication protocol transceiver module is respectively connected with a corresponding communication signal input end of the parallel structure switching module, and a logic signal input end of the parallel structure switching module is connected with a first logic signal output end of the upper computer; the communication signal output end of the parallel structure switching module is connected with the communication signal input end of the main-branch structure switching module, the communication signal output end of the main-branch structure switching module is connected with a plurality of communication pins of the OBD connector, and the logic signal input end of the main-branch structure switching module is connected with the second logic signal output end of the upper computer. The method and the device can be adapted to application scenes in which the positions of the diagnosis communication pins are uncertain in different vehicle types, and the flexibility and the universality of diagnosis link switching are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile diagnosis communication link protocol switching, in particular to an automobile diagnosis communication link protocol switching circuit and a control method. BACKGROUND

[0002] At present, a vehicle fault diagnosis instrument establishes communication with the OBD interface of a vehicle to read fault information and operation data in the electronic control unit of the vehicle, thereby realizing diagnosis of the operation state of the vehicle. Due to differences in diagnosis communication modes of different vehicle models, various diagnosis communication link protocols have been formed in the field of automobile diagnosis, and the diagnosis instrument needs to be switched between different communication protocols to adapt to the diagnosis requirements of different vehicles.

[0003] In the prior art, the switching of diagnosis communication links is usually realized by means of relays, discrete devices or analog switches, and the link structure is designed based on fixed OBD pin definitions. However, with the evolution of vehicle electronic architecture, more and more vehicle models no longer use the traditional defined OBD pin combination in diagnosis communication, for example, CAN2.0 communication is no longer limited to the 6th pin and the 14th pin, but can be distributed in other pin positions, thereby causing great uncertainty in the diagnosis communication pin combination.

[0004] Therefore, the existing diagnosis link switching scheme based on the fixed pin architecture is difficult to realize flexible switching of any OBD interface pins, and usually requires adding a large number of switching devices or redesigning the link structure, resulting in a significant increase in system complexity and cost, which is difficult to meet the diagnosis application requirements of multiple vehicle models and multiple pin combinations. SUMMARY

[0005] In order to solve the problem that the existing diagnosis communication link switching scheme is based on a fixed OBD pin architecture and is difficult to realize flexible switching of multiple protocols between any OBD interface pins, the present application provides an automobile diagnosis communication link protocol switching circuit and a control method.

[0006] An automobile diagnosis communication link protocol switching circuit, comprising a host computer, a communication protocol transceiver module, a parallel structure switching module, a total and partial structure switching module, and an OBD connector; A first data communication end of the communication protocol transceiver module is connected with a data communication end of a plurality of diagnosis elements applying different communication protocols, respectively, a second data end of the communication protocol transceiver module is connected with a corresponding communication signal input end of the parallel structure switching module, respectively, and a logic signal input end of the parallel structure switching module is connected with a 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 upper computer is used for selecting at most one target protocol in each communication protocol, and a first communication path is built through the parallel structure switching module, so that the communication signal corresponding to the target protocol is output to the total and partial structure switching module through the first communication path, and the communication signal corresponding to the communication protocol which is not selected is electrically isolated from the signal output end of the parallel structure switching module. The communication signal output end of the total and partial structure switching module is connected with the communication signal input end of the total and partial structure switching module, the upper computer is used for selecting at most one target protocol in each communication protocol, and a first communication path is built through the parallel structure switching module, so that the communication signal corresponding to the target protocol is output to the total and partial structure switching module through the first communication path, and the communication signal corresponding to the communication protocol which is not selected is electrically isolated from the signal output end of the parallel structure switching module.

[0007] By adopting the above technical scheme, by introducing a hierarchical switching architecture controlled by the upper computer in the diagnosis communication link, the selection of the communication protocol and the selection of the OBD physical pin are independently controlled, so that the diagnosis communication is no longer dependent on the fixed pin definition, so that flexible, controllable and mutually independent communication paths can be established between the multiple diagnosis communication protocols and the multiple communication pins of the OBD interface, thereby effectively solving the problem that different vehicle models are difficult to adapt when the diagnosis communication pin position is uncertain.

[0008] Preferably, the parallel structure switching module comprises at least one switching management chip, a plurality of groups of protocol transceiver ports and two bus output ports are arranged on the switching management chip, the protocol transceiver ports comprise CAN2 transceiver ports, single-wire CAN transceiver ports, K-line transceiver ports, L-line transceiver ports, PWM transceiver ports and VPW transceiver ports, the protocol transceiver ports are connected with data communication ends of a plurality of to-be-diagnosed elements applying different communication protocols, and the two bus output ports are connected with the signal input end of the total and partial structure switching module.

[0009] By adopting the above technical scheme, by concentrating the physical layer signals of multiple different diagnosis communication protocols into the parallel structure switching module, and under the unified control, the gating of a single target protocol is realized, so that the non-target protocol is electrically isolated from the rear link, thereby avoiding bus conflict and signal interference caused by simultaneous access of multiple protocols, and ensuring the stability and uniqueness of the diagnosis communication process.

[0010] Preferably, when the communication protocol corresponding to the protocol transceiver port is a differential communication protocol, two protocol transceiver ports corresponding to the differential communication protocol are provided, and are connected with the corresponding bus output ports respectively, so that the two bus output ports carry high-level signals and low-level signals of the differential communication protocol respectively; when the communication protocol corresponding to the protocol transceiver port is a single-wire communication protocol, only one protocol transceiver port corresponding to the single-wire communication protocol is provided, and is connected with any bus output port.

[0011] By using the above technical solution, different signal carrying modes are used for the differential communication protocol and the single-wire communication protocol, so that the high-level signals and the low-level signals of the differential protocol can be transmitted through independent channels respectively, and the single-wire protocol signal only occupies a single channel, thereby multiple diagnostic communication protocols with different physical layer characteristics are compatible under the same switching structure, and the adaptability of the system to protocol type changes is improved.

[0012] 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 with the protocol selection control port and the enable control port, the first management element is used for selecting at most one protocol transceiver port from a plurality of protocol transceiver ports according to a preset logic truth table, and is used for controlling the switching management chip to be in a conducting state or a cutoff state; the protocol selection control port includes a logic level A port and a logic level B port connected with the upper computer, the logic level A port and the logic level B port are connected with the built-in first management element of the switching management chip, each protocol transceiver port is connected with the corresponding bus output port through a first switch conducting element, and an enable signal output end of the first management element is connected with a controlled end of the first switch conducting element.

[0013] By using the above technical solution, the protocol selection and enable control mechanism based on the logic truth table is introduced into the switching management chip, so that the switching process of the communication protocol has clear logic determination rules, the communication path can be automatically blocked when an exception or a condition is not met, and the corresponding path is established when the condition is met, thereby improving the reliability and safety of the diagnostic communication switching process.

[0014] Preferably, the total and partial structure switching module comprises a first structure switch unit and a second structure switch unit, a communication signal input end of the first structure switch unit is connected with one bus output port, a communication signal input end of the second structure switch unit is connected with another bus output port, a logic signal input end of each of the first structure switch unit and the second structure switch unit is connected with a second logic signal output end of the upper computer, a plurality of first pin connection ports are arranged on a communication signal output end of the first structure switch unit, a plurality of second pin connection ports are arranged on a communication signal output end of the second structure switch unit, the first pin connection ports and the second pin connection ports are paired two by two, and the paired two-by-two common nodes are connected with corresponding communication pins.

[0015] By adopting the technical scheme, the communication signals from the parallel structure can be sequentially distributed to the plurality of communication pins of the OBD interface by introducing the total and partial structure switching mode on the communication bus, and the differential communication demand is supported by the paired structure, so that the flexible mapping of the plurality of OBD pins is realized without increasing the complex wiring, and the adaptation capability of the diagnostic link under different pin combinations is improved.

[0016] Preferably, the first structure switch unit and the second structure switch unit are both internally provided with a second management element, the first pin connection ports and the second pin connection ports are connected with the corresponding bus output ports through the second switch conduction elements, the controlled ends of the second switch conduction elements are connected with the enable signal output end of the second management element, the second management element is provided with a logic level A0 port, a logic level A1 port, a logic level A2 port and a logic level A3 port connected with the upper computer, and the second management element is provided with a second enable control port for controlling the first structure switch unit and the second structure switch unit to be in the conduction state or the cutoff state.

[0017] By adopting the technical scheme, the address logic control and the independent enable mechanism are introduced in the total and partial structure, so that the communication signal is only physically connected when the target pin is selected and in the allowed state, and the remaining pins are always in the disconnected state, thereby effectively avoiding the misconnection, parallel connection or transient interference, and ensuring the controllability and electrical safety of the diagnostic communication path.

[0018] A control method of an automobile diagnostic communication link protocol switching circuit, using an automobile diagnostic communication link protocol switching circuit, the control method comprises: obtaining diagnostic demand information of a to-be-diagnosed element, determining a target protocol based on the diagnostic demand 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 a conducting state; Based on the target protocol, the communication pin configuration relationship of the corresponding OBD connector is obtained, and the corresponding target pin is determined according to the communication pin configuration relationship. According to 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 total and partial structure switching module to build a second communication path, and the second enable control signal is used to control the total and partial structure switching module to be in a conducting state.

[0019] By adopting the above technical solution, by dividing the diagnosis communication process into target protocol determination, communication path establishment and target pin selection, the switching process of the diagnosis link forms a clear control flow, ensures that the communication protocol selection and the physical pin mapping have a clear sequence relationship, and thus improves the overall coordination and execution stability of the diagnosis system in a multi-protocol and multi-pin scene.

[0020] Preferably, in the step of generating a corresponding protocol selection control signal and a first enable control signal according to the target protocol, the step comprises: mapping the target protocol into corresponding protocol identification information; real-time acquisition of abnormal state information; calling a preset logical truth table, judging whether a corresponding first logic level combination can be determined based on the protocol identification information and the abnormal state information; if the corresponding first logic level combination cannot be determined, generating a first enable control signal for controlling the parallel structure switching module to be in a cut-off state; if the corresponding first logic level combination can be determined, generating a first enable control signal for controlling the parallel structure switching module to be in a conducting state, and generating a corresponding protocol selection control signal based on the first logic level combination.

[0021] By adopting the above technical solution, by introducing the protocol identification mapping, abnormal state judgment and logical truth table judgment mechanism in the protocol selection process, the protocol switching has the control ability of being determinable, blockable and recoverable, the link establishment can be prevented in time when the communication condition is not met, and the corresponding control signal is generated again when the condition is met, thereby reducing the influence of the error protocol selection on the diagnosis system.

[0022] Preferably, in the step of acquiring 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, the step comprises: Based on the target protocol, read out the communication pin configuration relationship of the corresponding OBD connector in the pre-stored configuration relationship table; According to the communication pin configuration relationship, filter out a candidate pin set meeting the communication requirement of the target protocol; Based on the pin availability constraint under the current diagnosis state, determine the target pin corresponding to the candidate pin set.

[0023] By adopting the above technical solution, the candidate pin set is generated based on the pre-stored communication pin configuration relationship after the protocol is determined, and the pin availability under the current diagnosis state is determined, so that the selection process of the target pin has a clear basis, and blind establishment of communication connection is avoided in the case of pin conflict or unavailability, thereby improving the adaptability and reliability of diagnosis communication in a complex vehicle interface environment.

[0024] Preferably, in the step of generating the corresponding pin selection control signal and the second enable control signal according to the target pin, the step comprises: mapping the target pin to corresponding pin identification information; determining whether the communication precondition is met in real time; if the communication precondition is not met, generating a second enable control signal for controlling the total and partial structure switching module to be in an off state; if the communication precondition is met, generating a second enable control signal for controlling the total and partial structure switching module to be in an on state, and calling a pre-set logic truth table to determine the corresponding second logic level combination according to the pin identification information; generating the corresponding pin selection control signal according to the second logic level combination.

[0025] By adopting the above technical solution, the pin information is converted into a logic level combination that can directly drive the switching structure under the premise that the target pin has been determined, and the physical connection is enabled and controlled in combination with the communication precondition, so that the diagnosis communication link is established only when the execution condition is met, effectively avoiding transient misconnection and unintended conduction in the switching process, and improving the safety and stability of the diagnosis communication execution phase.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: The application introduces a layered decoupling link switching structure in the automobile diagnosis communication link, that is, the selection of the communication protocol and the selection of the physical communication pin are separated from the same switching level, and are independently controlled through the parallel structure switching module and the total and partial structure switching module. First, the physical layer signals of multiple diagnosis communication protocols are uniformly accessed through the communication protocol transceiver module, and then the parallel structure switching module selects at most one target protocol from multiple communication protocols to establish a first communication path under the control of the upper computer, so that the communication protocols not selected are electrically isolated from the rear link, thereby avoiding the bus interference problem caused by multiple protocols accessing at the same time. After completing the unique selection of the communication protocol, the communication signal corresponding to the target protocol is not directly bound to the fixed OBD pin, but further introduces the total and partial structure switching module, which switches the communication signal to the target communication pin of the OBD connector according to the preset pin selection logic under the independent control of the upper computer, and the remaining communication pins not selected are in a disconnected state. Through the synergistic effect of the above two-level switching structure, the selection of the communication protocol and the mapping relationship of the OBD pin are decoupled from each other, thereby breaking through the structural limitation of the traditional diagnosis link relying on the fixed pin definition, and realizing the flexible switching of multiple diagnosis communication protocols between any communication pins of the OBD interface. The application can not only adapt to the application scene of uncertain diagnosis communication pin position in different vehicle models, but also significantly improve the flexibility and universality of the diagnosis link switching under the premise of ensuring the uniqueness and electrical isolation of the communication path, and provides a clear structure and strong scalability solution for multi-vehicle, multi-protocol automobile fault diagnosis. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a flow block diagram of an automobile diagnosis communication link protocol switching circuit in an embodiment of the application.

[0028] Figure 2 is a specific flow block diagram of the parallel structure switching module and the total and partial structure switching module in the automobile diagnosis communication link protocol switching circuit in an embodiment of the application. Figure 3 is a specific circuit structure schematic diagram of the built-in chip in the parallel structure switching module in the automobile diagnosis communication link protocol switching circuit in an embodiment of the application. Figure 4 is a specific circuit structure schematic diagram of the built-in chip in the total and partial structure switching module in the automobile diagnosis communication link protocol switching circuit in an embodiment of the application. Figure 5 is a flow chart of a control method of an automobile diagnosis communication link protocol switching circuit in an embodiment of the application. DETAILED DESCRIPTION

[0029] The application will be further described in detail below with reference to the accompanying drawings.

[0030] In an embodiment, as shown in Figure 1 The application discloses a car diagnosis communication link protocol switching circuit, which 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 first data communication end of the communication protocol transceiver module is connected with the data communication end of a plurality of application elements to be diagnosed in different communication protocols, and 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 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 host computer is used for selecting at most one target protocol from the communication protocols, and building a first communication path through the parallel structure switching module, so that the communication signal corresponding to the target protocol is output to the total and partial structure switching module through the first communication path. The communication signal output end of the total and partial structure switching module is connected with a plurality of communication pins of the OBD connector, and 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 host computer is used for selecting a corresponding target pin from the communication pins, so that the communication signal is communicated through the target pin, and the unselected communication pins are kept in a disconnected state with the signal output end of the parallel structure switching module.

[0031] In the embodiment, the automobile diagnosis communication link protocol switching circuit is composed of a host computer, a communication protocol transceiver module, a parallel structure switching module, a total and partial structure switching module, and an OBD connector, which form a clear hierarchical structure in the electrical connection relationship and control logic. The communication protocol transceiver module is used to complete the physical layer transceiving of different diagnosis communication protocols. The first data communication end of the communication protocol transceiver module is connected with the data communication end of the element to be diagnosed applying different communication protocols, so that the diagnosis communication signals from different electronic control units of the vehicle can complete the level conversion, driving and receiving processing according to the respective protocol characteristics. The second data communication end of the communication protocol transceiver module is connected with the corresponding communication signal input end of the parallel structure switching module, so as to uniformly introduce 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 total and partial structure switching module in the circuit structure. The logic signal input end of the parallel structure switching module is connected with the first logic signal output end of the host computer, so that the host computer can uniformly schedule and control different communication protocols according to the current diagnosis demand. In the actual working process, the parallel structure switching module allows at most one communication signal corresponding to the target protocol to be selected and output under the control of the host computer, and the rest of the unselected protocol communication signals are effectively isolated in the electrical aspect, so as to avoid the interference of multiple diagnosis communication signals entering the subsequent link at the protocol level. The communication signal selected by the parallel structure switching module is sent to the total and partial structure switching module through the communication signal output end thereof. The communication signal input end of the total and partial structure switching module is connected with the output end of the parallel structure switching module one by one, so that the communication signal of the selected target protocol can be further distributed to the OBD connector side. 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, so that the host computer can independently control the mapping relationship between the communication signal and each communication pin of the OBD connector after completing the selection of the communication protocol. In the working process, the total and partial structure switching module only connects the communication signal to the target communication pin according to the control signal given by the host computer, and the rest of the unselected communication pins are kept in the disconnected state with the communication link, so as to avoid the misconnection or crosstalk of the non-target pin. Through the above structure connection relationship and control logic, the host computer separately implements the 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 with the fixed definition of the OBD pin, thereby realizing the flexible switching between the diagnosis communication protocol and the OBD interface of any communication pin under the premise of ensuring the uniqueness of the communication path and the electrical isolation, which is suitable for the vehicle application scenarios where the diagnosis communication pin position is uncertain or changes frequently.

[0032] Further, as Figures 2-3The parallel structure switching module shown includes at least one switching management chip, and a plurality of protocol transceiving ports and two bus output ports are arranged on the switching management chip. The protocol transceiving ports include CAN2 transceiving ports, single-wire CAN transceiving ports, K-line transceiving ports, L-line transceiving ports, PWM transceiving ports and VPW transceiving ports. The protocol transceiving ports are respectively connected with data communication ends of a plurality of to-be-diagnosed elements applying different communication protocols. The two bus output ports are both connected with the signal input end of the total-distribution structure switching module.

[0033] In the embodiment, the parallel structure switching module is used to establish a controllable protocol gating relationship between a plurality of diagnostic communication protocols. The parallel structure switching module can be implemented by at least one switching management chip. The switching management chip is structurally provided with a plurality of protocol access ports for respectively accessing physical layer signals corresponding to different diagnostic communication protocols. For example, one group of protocol access ports can be used to receive communication signals from a CAN2.0 transceiver, and another group of protocol access ports 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 with an output side of a corresponding protocol in a communication protocol transceiving module, so that diagnostic communication signals of different protocols can be independently introduced into the switching management chip. In order to facilitate unified processing in the later stage, the switching management chip is further provided with two bus output ports as a unified signal output interface of the parallel structure switching module. The two bus output ports are both connected with the signal input end of the total-distribution structure switching module, so that the target protocol signal selected by gating can be further transmitted to the pin switching structure.

[0034] In actual work, all protocol access ports in the switching management chip are not simultaneously turned on, but only one group of ports is allowed to be electrically connected with the bus output ports in the plurality of protocol access ports through the control logic in the switching management chip. For example, when the CAN2.0 communication protocol is required for the current diagnostic task, the protocol access port corresponding to the CAN2.0 protocol is gated, and its communication signal is directed to the two bus output ports, while the other protocol access ports are kept disconnected from the bus output ports. When the diagnostic task is switched to a single-wire communication protocol, only the protocol access port corresponding to the single-wire protocol is gated, and its communication signal is directed to one of the bus output ports, while the other bus output port is in an idle state. Through the above method, different diagnostic communication protocols are mutually exclusive and gated before entering the later stage circuit, so that the parallel structure switching module plays a role of centralized gathering and unique output at the protocol level.

[0035] Further, as shown in FIG. 6, the parallel structure switching module is used to establish a controllable protocol gating relationship between a plurality of diagnostic communication protocols. The parallel structure switching module can be implemented by at least one switching management chip. The switching management chip is structurally provided with a plurality of protocol access ports for respectively accessing physical layer signals corresponding to different diagnostic communication protocols. For example, one group of protocol access ports can be used to receive communication signals from a CAN2.0 transceiver, and another group of protocol access ports 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 with an output side of a corresponding protocol in a communication protocol transceiving module, so that diagnostic communication signals of different protocols can be independently introduced into the switching management chip. In order to facilitate unified processing in the later stage, the switching management chip is further provided with two bus output ports as a unified signal output interface of the parallel structure switching module. The two bus output ports are both connected with the signal input end of the total-distribution structure switching module, so that the target protocol signal selected by gating can be further transmitted to the pin switching structure. Figure 3As shown, when the communication protocol corresponding to the protocol transceiver port is a differential communication protocol, two protocol transceiver ports corresponding to the differential communication protocol are provided and connected with the corresponding bus output ports, respectively, so that the two bus output ports carry high-level signals and low-level signals of the differential communication protocol, respectively. When the communication protocol corresponding to the protocol transceiver port is a single-wire communication protocol, only one protocol transceiver port corresponding to the single-wire communication protocol is provided and connected with any bus output port.

[0036] In the embodiment, in order to adapt to the differences in the physical layer structure of different diagnostic communication protocols, the parallel structure switching module is designed differently for the differential communication protocol and the single-wire communication protocol in the configuration mode of the protocol access port. For the differential communication protocol, such as CAN2.0 or PWM differential transmission protocol, the communication signal on the physical layer is composed of a pair of mutually referenced signal lines, which carry high-level signals and low-level signals, respectively. In this case, the switching management chip sets two groups of independent protocol access ports for each differential communication protocol, one group of ports is used to receive the high-level component of the differential signal, and the other group of ports is used to receive the low-level component of the differential signal. The two groups of ports are respectively connected with the corresponding differential output end in the communication protocol transceiver module in electrical connection. When the above two groups of protocol access ports are selected, they respectively 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 a paired manner, thereby maintaining the integrity and symmetry of the differential signal inside the parallel structure switching module, and avoiding common mode interference or signal distortion caused by signal merging or multiplexing.

[0037] For the single-wire communication protocol, such as single-wire CAN, K-line, L-line, or VPW protocol, its communication process only relies on a single signal line to complete data transmission, and does not need to transmit differential signals in pairs. In this case, the switching management chip only sets a group of corresponding protocol access ports for each single-wire communication protocol, which is connected with the output end of the corresponding single-wire protocol in the communication protocol transceiver module in electrical connection. When the single-wire communication protocol is selected, its protocol access port only establishes a conduction relationship with one of the bus output ports inside the switching management chip, and the other bus output port remains unconnected or idle, thereby avoiding unnecessary distribution of single-wire signals to multiple channels inside the parallel structure switching module. Through this configuration mode, the parallel structure switching module can simultaneously support differential communication protocols and single-wire communication protocols under the same hardware structure, without the need to design independent switching channels for different protocol types.

[0038] Further, as shown in FIG. 6, the parallel structure switching module 100 is connected with the communication protocol transceiver module 200 through the protocol access port 101, and the communication protocol transceiver module 200 is connected with the external communication bus 300 through the bus output port 201. Figure 3As shown, 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 with the protocol selection control port and the enable control port, the first management element is used for selecting at most one group of protocol transceiver ports from a plurality of groups of protocol transceiver ports according to a preset logic truth table, and is used for controlling the switching management chip to be in a conducting state or a cutoff state; the protocol selection control port comprises a logic level A port and a logic level B port which are connected with the upper computer, the logic level A port and the logic level B port are connected with the built-in first management element of the switching management chip, each protocol transceiver port is connected with a corresponding bus output port through a first switch conducting element, and an enable signal output end of the first management element is connected with a controlled end of the first switch conducting element.

[0039] In the embodiment, the protocol gating and isolation control inside the parallel structure switching module is realized by the control structure inside the switching management chip, the switching management chip is provided with a protocol selection control port for receiving external control instructions and a first enable control port for controlling the overall conducting state. The protocol selection control port can be composed of a plurality of logic level input ends, for example, two-way logic input ports are set, which are used for receiving protocol selection encoding signals output from the upper computer, and the encoding signals correspond to different diagnostic communication protocols in the form of different logic level combinations. The first enable control port is used for receiving an enable signal output from the upper computer, which is used to indicate whether the protocol level communication path is currently allowed to be established, when the port is in an invalid state, the switching management chip inside does not establish a conducting relationship between any protocol access port and the bus output port.

[0040] The switching management chip is provided with a first management element inside, which can be realized by a logic decoding circuit, a state control circuit or a combination thereof, and is used for analyzing the logic level input of the protocol selection control port. The first management element is pre-configured with a set of logic truth table inside, which is used to define the correspondence between different logic level combinations of the protocol selection control port and specific protocol access ports. In the actual working process, when the first enable control port indicates that the conducting is allowed, the first management element decodes the current input protocol selection encoding according to the logic truth table, and determines a unique target protocol access port from a plurality of protocol access ports; when the first enable control port indicates that it is in a cutoff state, the first management element ignores the input state of the protocol selection control port, and forcibly controls all protocol access ports to be in a non-gating state.

[0041] In the switch management chip, a first switch-on element is arranged between each group of protocol access ports and the corresponding bus output port. The first switch-on element can be realized in the form of an analog switch, a controlled transistor or a field effect transistor, and its control end is connected with the control output end of the first management element. After the first management element determines the target protocol access port, it outputs a switch-on control signal to the first switch-on element corresponding to the target protocol access port, so that the first switch-on element enters the switch-on 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 switch-on elements corresponding to other non-target protocol access ports in the off state, so that the communication signals of the non-target protocols are completely isolated from the bus output port in an electrical manner.

[0042] Further, as shown in Figure 2 and Figure 4 , the total and partial structure switch module includes a first structure switch unit and a second structure switch unit, the communication signal input end of the first structure switch unit is connected with a bus output port, the communication signal input end of the second structure switch unit is connected with another bus output port, the logic signal input ends of the first structure switch unit and the second structure switch unit are both connected with the second logic signal output end of the upper computer, the communication signal output end of the first structure switch unit is provided with a plurality of first pin connection ports, the communication signal output end of the second structure switch unit is provided with a plurality of second pin connection ports, the first pin connection ports and the second pin connection ports are paired, and the paired common nodes are connected with the corresponding communication pins.

[0043] In the embodiment, the total and partial structure switch module is used to realize the controllable distribution of communication signals among the plurality of physical pins of the OBD connector, and the overall structure is composed of two groups of independent structure switch units, which are symmetrical in function and respectively bear different communication channels from the parallel structure switch module in electrical connection. Specifically, one group of structure switch units is used to receive the first bus signal from the parallel structure switch module, and the other group of structure switch units is used to receive the second bus signal from the parallel structure switch module. The two bus signals remain independent after entering the total and partial structure switch module, thereby providing a unified structural basis for differential communication and single-wire communication. The input side of each group of structure switch units is connected with the corresponding bus output channel of the parallel structure switch module through wiring, and the output side respectively leads out a plurality of pin connection channels for selectively connecting with each communication pin of the OBD connector.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In the structural connection relationship, the pin connection ports of the first and second structural switch units are connected to their respective bus input channels through corresponding second switch conduction elements. The second switch conduction elements can be realized by analog switches, electrically controlled transistors or field effect tubes, etc., and their control ends are uniformly connected to the control output end of the second management element. When the second management element receives A0-A3 logic level input, it decodes the address code according to the preset logic truth value relationship and determines the target pin channel that needs to establish a conduction relationship. In this process, only the second switch conduction element corresponding to the target pin is controlled to enter the conduction state, so that the communication signal from the parallel structure switching module is connected to the target OBD communication pin through the corresponding structural switch unit, and the remaining second switch conduction elements corresponding to the non-target pin remain in the off state, thereby realizing the unique selection of the communication path at the pin level.

[0048] To enhance the controllability and safety of the pin switching process, the second management element is also provided with an independent second enable control port for uniformly controlling the on or off state of the total and partial structure switching module. When the second enable control port is not activated, the second management element controls all second switch conduction elements to be in the off state regardless of the A0-A3 input state, so that the communication signal and each communication pin of the OBD connector remain disconnected, thereby avoiding the misconnection phenomenon during system power-on, control signal switching or non-communication stage; when the second enable control port is activated, the second management element selectively turns on the corresponding second switch conduction element according to the current A0-A3 address code result to establish an effective pin-level communication path.

[0049] As shown in Figure 5 A control method of an automobile diagnostic communication link protocol switching circuit, using an automobile diagnostic communication link protocol switching circuit, the control method comprising: S10, obtaining diagnosis demand information of a to-be-diagnosed element, and determining a target protocol based on the diagnosis demand information; S20, generating a corresponding protocol selection control signal and a first enable control signal according to the target protocol, the protocol selection control signal being used to control the parallel structure switching module to build a first communication path, and the first enable control signal being used to control the parallel structure switching module to be in a conduction state; S30, obtaining a communication pin configuration relationship of a corresponding OBD connector based on the target protocol, and determining a corresponding target pin according to the communication pin configuration relationship; S40, generating a corresponding pin selection control signal and a second enable control signal according to the target pin, the pin selection control signal being used to control the total and partial structure switching module to build a second communication path, and the second enable control signal being used to control the total and partial structure switching module to be in a conduction state.

[0050] In the embodiment, the element to be diagnosed refers to an electronic control unit installed on a vehicle or a functional module with a diagnostic communication interface, such as an engine control unit, a transmission control unit, a vehicle body control module, or an emission control related module, etc. The diagnostic communication path is usually established through the vehicle internal bus and the OBD interface. The diagnostic requirement information refers to control information used to describe the current diagnostic task target, which can be generated by the host computer when entering the diagnostic process, and specifically includes the type identification of the element to be diagnosed, the current diagnostic stage, the required data category to be read, or the communication mode constraint, etc. The diagnostic requirement information is used as the basis for subsequent communication strategy selection. The target protocol refers to the unique communication protocol selected from the multiple diagnostic communication protocols supported by the system for establishing communication with the element to be diagnosed after analyzing the diagnostic requirement information. The target protocol remains determined within the same diagnostic cycle to avoid conflicts in communication rules.

[0051] The protocol selection control signal is a control signal generated by the host computer according to the target protocol, which can be represented as a set of logic level codes in engineering implementation, used to indicate the protocol channel position to be selected within the parallel structure switching module. The first enable control signal is a control signal cooperating with the protocol selection control signal, 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 to perform switching action. When the signal is in an inactive state, the parallel structure switching module remains in all protocol path disconnected state. The parallel structure switching module is a protocol level switching unit located between the communication protocol transceiver module and the rear pin switching structure, which functions to select only the communication signal corresponding to the target protocol in multiple diagnostic communication protocols, and electrically isolate other protocol communication signals that are not selected, 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. The communication path is used to transmit the communication signal of the target protocol to the rear circuit.

[0052] The communication pin configuration relationship refers to a data set pre-established to describe the correspondence between different diagnostic communication protocols and OBD connector communication pins. The configuration relationship can be stored in the form of table, mapping rule or parameterized data in the host computer or control system, used to reflect the communication pin positions that different protocols may use under different vehicle or interface specifications. The target pin refers to the OBD connector communication pin finally determined for actual communication according to the communication pin configuration relationship and in combination with the current diagnostic state after screening under the premise that the target protocol has been determined. The target pin remains unique within a diagnostic communication cycle to ensure stable communication path.

[0053] The pin selection control signal is a control signal generated by the host computer according to the target pin, which can be represented as a set of address logic codes in engineering implementation, used to indicate the pin channel position that needs to be turned on inside the total-distribution structure switching module. The second enable control signal is a control signal used to control whether the total-distribution structure switching module allows to establish a physical pin connection. When the second enable control signal is in an effective state, the total-distribution structure switching module establishes the corresponding physical connection relationship according to the pin selection control signal; when the signal is in an invalid state, the total-distribution structure switching module keeps all pin channels disconnected. The total-distribution structure switching module is a pin-level switching unit located between the parallel structure switching module and the OBD connector, which functions to distribute the communication signals from the first communication path to the target communication pins of the OBD connector as needed, and ensures that the other pins not selected 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 and the target pin after mapping by the total-distribution structure switching module. The second communication path is used to realize the actual data interaction between the diagnostic instrument and the element to be diagnosed.

[0054] Further, in the step of generating the corresponding protocol selection control signal and the first enable control signal according to the target protocol, the step includes: S201, mapping the target protocol into corresponding protocol identification information; S202, acquiring abnormal state information in real time; S203, calling a preset logic truth table, and judging whether the corresponding first logic level combination can be determined based on the protocol identification information and the abnormal state information; S204, if the corresponding first logic level combination cannot be determined, generating the first enable control signal used to control the parallel structure switching module to be in a cutoff state; S205, if the corresponding first logic level combination can be determined, generating the first enable control signal used to control the parallel structure switching module to be in a conduction state, and generating the corresponding protocol selection control signal based on the first logic level combination.

[0055] In the embodiment, the target protocol refers to a unique diagnostic communication protocol determined in the pre-diagnosis process for establishing communication with the element to be diagnosed, which remains stable in the current diagnosis cycle and is used as the basis for protocol-level switching and control. The protocol identification information is the result of engineering expression of the target protocol, which is not the protocol itself but an abstract identification form for controlling the internal switching logic of the circuit. For example, different diagnostic communication protocols can be represented in the form of digital coding, enumeration number or logical index, enabling the control system to distinguish and process different protocols in a unified format. By mapping the target protocol to protocol identification information, the control logic can avoid directly processing complex protocol names or protocol characteristics in subsequent control logic, thereby improving the universality and realizability of the control logic.

[0056] The abnormal state information refers to a set of state information reflecting whether the current system operating state meets the condition for establishing a protocol-level communication path during protocol switching and communication preparation. The abnormal state information can be derived from the internal state monitoring results of the host computer, feedback signals of the communication module or circuit-level detection signals, and is used to indicate whether the system has conditions that do not allow protocol switching or communication establishment, such as incomplete initialization, unstable state during switching or detection of abnormal operating conditions. The abnormal state information is used as a constraint condition in the subsequent logic judgment in this step, to prevent forced establishment of a communication path in an inappropriate system state.

[0057] The logic truth table is a pre-set control rule data used to define the control results corresponding to different protocol identification information in different system states, which can be implemented in the form of lookup table, rule mapping or fixed logic relationship. The logic truth table is used in engineering to describe the combination of protocol identification information and abnormal state information as input conditions, and the control decision results to be output when the conditions are met or not met. The first logic level combination refers to a set of logic level signals obtained by calling the logic truth table when the pre-set conditions are met, which is used to drive the parallel structure switching module. The logic level combination usually consists of multiple logic signals, which are used to explicitly indicate the protocol channel position to be selected in the parallel structure switching module.

[0058] When the protocol identification information and abnormal state information cannot determine an effective first logic level combination based on the logic truth table, it means that the current system state does not meet the condition for establishing a protocol-level communication path. In this case, the first enable control signal is generated to control the parallel structure switching module to remain in the off state, maintaining the disconnection between the internal protocol channels and the subsequent circuit, thereby avoiding the misselection of communication protocols in abnormal or unstable states. The first enable control signal plays a role in blocking the protocol-level communication path in this case, ensuring that the system is in a safe non-communication state.

[0059] When the corresponding first logic level combination can be determined by the logical truth table based on the protocol identification information and the abnormal state information, it indicates that the current system state allows the establishment of a protocol-level communication path, and the generated first enable control signal is used to control the parallel structure switching module to enter the conduction state, so that it can respond to the protocol selection control signal to perform switching actions. The protocol selection control signal is a control signal generated based on the first logic level combination, which can be expressed as a set of explicit logic level outputs in engineering implementation, used to drive the switch conduction elements inside the parallel structure switching module, so as to select the communication channel corresponding to the target protocol in the multiple diagnostic communication protocol channels, and introduce the communication signal of the target protocol into the subsequent link.

[0060] Further, based on the target protocol, the communication pin configuration relationship of the corresponding OBD connector is obtained, and in the step of determining the corresponding target pin according to the communication pin configuration relationship, the step includes: S301, based on the target protocol, reading out the communication pin configuration relationship of the corresponding OBD connector from the pre-stored configuration relationship table; S302, according to the communication pin configuration relationship, screening out a candidate pin set meeting the communication requirements of the target protocol; S303, based on the pin availability constraint under the current diagnostic state, judging the candidate pin set to determine the corresponding target pin.

[0061] In the embodiment, the target protocol is the diagnostic communication protocol type determined in the previous step, which is used to limit the physical layer communication conditions required to be met in the subsequent pin selection process. The pre-stored configuration relationship table is a pin mapping data structure established and stored in the host computer or control system in advance, which is used to describe the available OBD connector communication pin combination information corresponding to different diagnostic communication protocols under different vehicle or interface specifications. The configuration relationship table can be derived from standard protocol specifications, vehicle manufacturer definitions or historical diagnostic experience data, and is maintained in a parameterized form, so that the system can quickly obtain the pin configuration relationship matching the target protocol without manual intervention during operation.

[0062] The communication pin configuration relationship is the pin mapping result directly corresponding to the target protocol read from the configuration relationship table, which is used to explicitly indicate the OBD communication pin positions and their combination methods allowed to be used by the target protocol at the physical connection level. The communication pin configuration relationship not only describes the number information of a single pin, but also can include the paired relationship, signal direction attribute and necessary electrical characteristic constraint of the pin in the differential communication or single-wire communication scene, thereby providing complete engineering basis for subsequent pin screening. By introducing the communication pin configuration relationship, the pin selection process is consistent with the specific protocol characteristics, avoiding the situation that the protocol level is available but the physical connection is not matched.

[0063] The candidate pin set refers to a set of OBD communication pins that meet the basic communication requirements of the target protocol after analyzing the communication pin configuration relationship. The pins in this set all have the possibility to establish communication channels at the protocol specification level. This screening process is used to eliminate pins that are incompatible with the target protocol, such as not meeting the differential pair requirement or not having the corresponding signal function, thereby narrowing the subsequent determination range and improving the reliability and efficiency of pin selection. The generation of the candidate pin set enables the system to make preliminary constraints based on protocol characteristics when facing multiple possible pin combinations.

[0064] The pin availability constraint is a state condition used to reflect whether each communication pin is allowed to be occupied under the current diagnosis state. It can consider factors such as the current diagnosis stage, existing communication connection situation, system resource occupation state, or safety control requirements. In engineering implementation, the pin availability constraint can be reflected by state flags, locking mechanisms, or real-time detection results to prevent multiple communication tasks from competing for the same physical pin in the same time period. By applying the pin availability constraint to the candidate pin set, currently unavailable pin options can be further excluded while meeting the protocol requirements.

[0065] The target pin refers to the OBD connector communication pin that is finally determined to establish an actual communication connection after integrating the communication pin configuration relationship, the candidate pin set, and the pin availability constraint under the current diagnosis state. This target pin remains unique and deterministic within the current diagnosis cycle to ensure stable execution of subsequent pin-level switching and communication processes. Through the above determination process, the determination of the target pin meets both the communication characteristics of the target protocol and the engineering feasibility requirements under the current system operating state.

[0066] Further, in the step of generating the corresponding pin selection control signal and the second enable control signal according to the target pin, the step includes: S401, mapping the target pin to corresponding pin identification information; S402, determining whether the communication precondition is met in real time; S403, if the communication precondition is not met, generating a second enable control signal for controlling the total and partial structure switching module to be in the cutoff state; S404, if the communication precondition is met, generating a second enable control signal for controlling the total and partial structure switching module to be in the on state, and calling a pre-set logic truth table to determine the corresponding second logic level combination according to the pin identification information; S404, generating the corresponding pin selection control signal according to the second logic level combination.

[0067] In the embodiment, the process of generating the pin selection control signal and the second enable control signal according to the target pin has a similar execution framework as the aforementioned protocol level switching process in the overall control logic, but there are obvious differences in the control object and the basis for judgment. Compared with the 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, and the control granularity is further refined from the 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 to represent the position code of the target pin in the OBD connector, so that the total-structure switching module can accurately map the communication signal to the corresponding physical pin.

[0068] The second enable control signal is similar in function to the first enable control signal, both of which are used to control whether the corresponding switching module allows the establishment of a communication path, but its scope of action is limited to the pin level switching structure. When the second enable control signal is in the inactive state, even if the target pin has been determined and the corresponding pin selection control signal has been generated, the total-structure switching module still maintains the state of all pin paths being disconnected, in order to avoid establishing a physical connection prematurely in the case where the pin state is not ready or the communication conditions are not met; when the second enable control signal is in the active state, the total-structure switching module only performs the specific pin conduction operation according to the pin selection control signal. By independently enabling the pin level switching and the protocol level switching process, the system can further accurately control the communication path at the physical pin level after the protocol confirmation is completed, thereby reducing the risk of misconnection, short-time parallel connection, or pin conflict.

[0069] Specifically, the automobile diagnostic communication link protocol switching circuit is used to establish a controllable communication connection between multiple automobile diagnostic communication protocols and multiple communication pins of the OBD connector, in order to meet the communication needs 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 total-structure switching module, wherein the modules are connected in sequence according to the signal processing order.

[0070] The communication protocol transceiver module is used to provide physical layer transceiving functions for multiple automobile diagnostic communication protocols, which can support diagnostic communication protocols including CAN2.0, single-wire CAN, K-line, L-line, PWM, and VPW, and is suitable for diagnostic communication scenarios of 12V passenger car systems or 24V passenger car systems according to the differences in vehicle power supply systems. For differential communication protocols, the communication protocol transceiver module outputs high-level signals and low-level signals respectively; for single-wire communication protocols, the communication protocol transceiver module only outputs a single communication signal.

[0071] The parallel structure switching module is connected with the communication protocol transceiver module, and is used for selecting a target protocol from multiple communication protocols and establishing a first communication path. The parallel structure switching module is internally provided with multiple groups of protocol access channels, and the communication signals of the target protocol are collected to two bus output channels through a controlled switch conduction structure, one of which is a first bus output channel and the other is a second bus output channel. For a differential communication protocol, 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 a single-wire communication protocol, the communication signal is output through one of the bus output channels, and the other bus output channel remains in a closed state.

[0072] The bus-branch structure switching module is connected with the first bus output channel and the second bus output channel respectively, and is used for switching the communication signals from the parallel structure switching module to the target communication pins of the OBD connector as needed. The OBD connector includes multiple pins, and the number of pins used for communication is less than the total number of pins. The bus-branch structure switching module can select a target pin from the communication pins, and keep electrical isolation between the unselected pins and the communication signals.

[0073] The working process of the embodiment is described below in combination with a specific communication protocol example.

[0074] When the automobile diagnostic instrument communicates with the first communication pin and the ninth communication pin of the OBD connector through the CAN2.0 communication protocol, the CAN high-level signal output by the communication protocol transceiver module enters the first bus output channel after being selected by the parallel structure switching module, and the CAN low-level signal enters the second bus output channel after being selected by the parallel structure switching module; then, the bus-branch structure switching module switches the communication signals in the first bus output channel to the first communication pin and switches the communication signals in the second bus output channel to the ninth communication pin, thereby establishing a complete differential communication path.

[0075] When the automobile diagnostic instrument communicates with the seventh communication pin and the fifteenth communication pin of the OBD connector through the K-line and L-line communication protocol, the K-line signal output by the communication protocol transceiver module enters the first bus output channel after being selected by the parallel structure switching module, and the L-line signal enters the second bus output channel after being selected by the parallel structure switching module; then, the bus-branch structure switching module switches the signals in the first bus output channel to the seventh communication pin and switches the signals in the second bus output channel to the fifteenth communication pin, so as to realize the communication connection of the corresponding protocol.

[0076] When the automobile diagnostic instrument communicates with the second communication pin and the tenth communication pin of the OBD connector through the PWM communication protocol, the PWM high level signal output by the communication protocol transceiver module enters the first bus output channel after being selected by the parallel structure switching module, and the PWM low level signal enters the second bus output channel after being selected by the parallel structure switching module; the bus-branch structure switching module switches the above two communication signals to the corresponding communication pins according to the control signal, so as to complete the communication connection of the PWM protocol.

[0077] When the automobile diagnostic instrument communicates with the first communication pin of the OBD connector through the single-wire CAN communication protocol, the single-wire CAN signal output by the communication protocol transceiver module enters the first bus output channel after being selected by the parallel structure switching module, and the second bus output channel remains in a closed state; the bus-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.

[0078] When the automobile diagnostic instrument communicates with the second communication pin of the OBD connector through the VPW communication protocol, the VPW signal output by the communication protocol transceiver module enters the first bus output channel after being selected by the parallel structure switching module, and the second bus output channel remains in a closed state; the bus-branch structure switching module switches the communication signal in the first bus output channel to the second communication pin, thereby realizing the communication connection of the VPW protocol.

[0079] Through the above structure and working mode, the embodiment can realize flexible switching between various diagnostic communication protocols and multiple communication pins of the OBD connector, and ensure that when any communication protocol is selected, the signal path corresponding to other communication protocols remains in a closed state, thereby avoiding signal interference and the risk of electric leakage, reducing the number of devices, making the overall circuit structure compact, and being suitable for integrated application.

[0080] The logic truth table of the parallel structure switching module is shown in the following table:

[0081] The logic truth table of the bus-branch structure switching module is shown in the following table: enabled 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 The above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present 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 build 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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