Transceiver device for a subscriber station of a serial bus system, and method for a communication using differential signals in a serial bus system

Abstract

The invention relates to a transceiver device (12) for a subscriber station (10; 30) of a serial bus system (1; 1A) and to a method for a communication using differential signals in a serial bus system (1; 1A). The transceiver device has a transmitting module (121) for transmitting a digital transmission signal (TxD; Tx) as an analog differential signal (CAN_H, CAN_L; LINE+, LINE-) to a bus (40; 40A) of the bus system (1; 1A) in order to transmit a message (45; 48) to at least one other subscriber station (10; 20; 30) of the bus system (1; 1A), a receiving module (122) for receiving signals (CAN_H, CAN_L; LINE+, LINE-) from the bus (40; 40A) and for generating a digital received signal (RxD; Rx) from the analog differential signal (CAN_H, CAN_L; LINE+, LINE-), a first connection (TXD / TX) for receiving the transmission signal (TxD; Tx) from a communication control device (11; 11A), a second connection (RXD / RX) for outputting the digital received signal (RxD; Rx) to the communication control device (11; 11A), and a COM-IF detection module (124) for evaluating whether the digital transmission signal (TxD; Tx) at the first connection (TXD / TX) has at least one specified property of a communication standard of two communication standards (CAN; 10BASE- T1S) for which the transmitting module (121) and the receiving module (122) are designed for communication in the serial bus system (1; 1A), said transceiver device (12) being adjustable for the communication on the bus (40; 40A) on the basis of the evaluation result of the COM-IF detection module (124).

Description

[0001] Description

[0002] Transmitting / receiving device for a subscriber station of a serial bus system and method for communication with differential signals in a serial bus system

[0003] The present invention relates to a transmit / receive device for a subscriber station of a serial bus system and a method for communication with differential signals in a serial bus system.

[0004] State of the art

[0005] Serial bus systems have a bus to which participating devices are connected via a transceiver to communicate with each other. During communication, data is exchanged between the participating devices, which can be, for example, sensors, control units in a vehicle or a production plant, etc. Various standards or data transmission protocols exist for data transmission in serial bus systems. Well-known standards for serial bus systems with differential signals include CAN XL, 10BASE-T1 S-Ethernet, FlexRay, LVDS (Low Voltage Differential Signaling), and others.

[0006] Each of these serial bus systems uses differential signals with different signal states, which serially signal the data to be exchanged.

[0007] It is possible that one part of the technical system uses a bus system with a different communication standard than another part. For example, a CAN bus system might be used for communication in a vehicle's emergency braking system, whereas a 10BASE-T1 S-bus system might be used for communication in a windshield wiper system.

[0008] The problem is that communication in the CAN bus system and communication in the 10BASE-T1 S-bus system are not compatible. For example, if at least one control unit needs to be replaced due to a defect, a replacement control unit that supports the communication standard of the bus system to which the replaced control unit was connected is not always available in time.

[0009] In addition, the data from some of the vehicle's devices, such as a rain sensor or a warning signal generator, etc., are needed for parts of the technical system that communicate using different communication standards.

[0010] To solve this problem, two devices, in particular two rain sensors and / or warning signal generators, etc., could be used, one of which is connected to the CAN bus system and the other to the 10BASE-T1 S-bus system.

[0011] Alternatively, such a device may have communication devices designed for communication in the CAN bus system and communication devices designed for communication in the 10BASE-T1 S-bus system.

[0012] However, this requires significantly more equipment than a technical system that uses only one communication standard. Consequently, the technical system requires more space and is considerably more expensive to manufacture and maintain.

[0013] Disclosure of the invention

[0014] Therefore, the object of the present invention is to provide a transmit / receive device for a subscriber station of a serial bus system and a method for communication with differential signals in a serial bus system, which solve the aforementioned problems. In particular, a transmit / receive device for a subscriber station of a serial bus system and a method for communication with differential signals in a serial bus system are to be provided that solve the compatibility problem between different communication standards in a technical system.

[0015] The problem is solved by a transmit / receive device for a subscriber station of a serial bus system with the features of claim 1. The transmit / receive device has a transmit module for sending a digital transmit signal as an analog differential signal to a bus of the bus system in order to send a message to at least one other subscriber station of the bus system, a receive module for receiving signals from the bus and for generating a digital receive signal from the analog differential signal, a first connection for receiving the transmit signal from a communication control device, a second connection for outputting the digital receive signal to the communication control device, and a COM-IF detection module for evaluating whether the digital transmit signal at the first connection has at least one predetermined property of a communication standard of two communication standards.for which the transmit module and the receive module are designed for communication in the serial bus system, wherein the transmit / receive device for communication on the bus is adjustable based on the evaluation result of the COM-IF acquisition module.

[0016] The described transceiver can use a special module at the digital transmit signal port to detect whether the combined transceiver should behave according to the 10BASE-T1 S standard or the CAN-XL standard, without requiring an additional port or non-standard inputs from the communication control unit, particularly its controller. The module is designed to recognize the patterns transmitted by the connected communication control unit at the digital transmit signal port for communication within the bus system.

[0017] Thus, the described transmitter / receiver device can independently recognize which communication standard a connected communication control device uses. This results in a very high degree of flexibility for selecting the communication standard for the bus system and thus the communication control device, provided the described transmitter / receiver device is connected to the bus in its original configuration.

[0018] An additional advantage is that electrical circuit components, such as the power supply, etc., of the described transceiver can be used for two different communication standards. As a result, the described transceiver can save semiconductor space. This optimizes the space requirements of the transceiver and the bus system. Consequently, the described transceiver is extremely resource-efficient and cost-effective.

[0019] Due to the design of the described transceiver, the effort required to adapt the communication control unit to the transceiver is very low. Only the wiring of the connections (pins) for the bus lines needs to be adapted to the communication control unit being used.

[0020] Furthermore, due to the design of the described transmitting / receiving device, reliable communication with a very low error rate is nevertheless enabled in an uncomplicated and cost-effective manner for at least two different differential bus systems.

[0021] The described transceiver enables a relatively simple change in the communication standard for an existing wiring setup. This is because the described transceiver can be used with minimal configuration effort for bus systems that support communication using different communication standards. If necessary, this also allows an existing device in a technical system, particularly a vehicle, to be flexibly connected to different bus systems that support communication using different communication standards, as required.

[0022] The described transmit / receive device is designed to be configured as a CAN SIC transmit / receive device and / or CAN XL transmit / receive device and / or 10BASE-T1 S transmit / receive device, depending on the connected communication control device.

[0023] Overall, the described transmitting / receiving device can not only realize communication in the bus system between other subscriber stations with the (high) bit rates required for the respective communication standard, but is also designed in such a way that the transmissible bit rate is not reduced by errors in the communication.

[0024] The described transceiver can be used particularly for gateway products. Such gateway products typically include a power supply unit and several interfaces. For example, a voltage supply U_bat is regulated to 5V to operate multiple CAN transceivers and / or LIN transceivers. Such a gateway can contain several identical transceivers as described above, which can then be operated by Tierl as transceivers for CAN-XL (CAN-SIC) or 10BASE-T1 S via the controller.

[0025] Further advantageous configurations of the transmitting / receiving device are described in the dependent claims.

[0026] The previously described transmit / receive device may also have a third connection for setting one of two predetermined voltage levels, with the COM-IF detection module also being designed to evaluate whether the digital transmit signal at the first connection occurs in combination with one of the two predetermined voltage levels at the third connection.

[0027] According to one embodiment, the COM-IF acquisition module is designed to evaluate, with regard to the presence of a first predetermined property of a communication standard of the two communication standards, whether signal edges occur at the first connection in combination with a predetermined first voltage level of the two predetermined voltage levels at the third connection.

[0028] Additionally or alternatively, the COM-IF detection module can be designed to evaluate, with regard to the presence of a second predetermined property of a communication standard of the two communication standards, whether reset commands are periodically received at the first terminal in combination with a predetermined second voltage level of the two predetermined voltage levels at the third terminal.

[0029] Optionally, the COM-IF acquisition module is designed to perform its evaluation with regard to the presence of the second predetermined property of one of the two communication standards only after a period of time has elapsed which corresponds to the maximum frame length of a frame which is used for the message when communicating with one of the two communication standards.

[0030] Additionally or alternatively, the COM-IF acquisition module can be designed to evaluate, with regard to the presence of a third predetermined property of a communication standard of the two communication standards, which minimum symbol length of the transmitted signal is captured.

[0031] Additionally or alternatively, the COM-IF acquisition module can be configured to evaluate, with respect to the presence of a fourth predetermined property of one of the two communication standards, which duty cycle of a symbol of the transmitted signal is being acquired. The previously described transmit / receive device may also have an operating mode selection module for selecting an operating mode of the transmit module and / or the receive module based on an evaluation result of the COM-IF acquisition module.

[0032] The operating mode selection module can be designed to also evaluate the transmitted signal at the first terminal and the voltage level at the third terminal in order to select the operating mode of the transmitting module and / or the receiving module.

[0033] Additionally or alternatively, it is possible that the COM-IF determination module is designed to further evaluate the transmitted signal with regard to at least one predetermined property after passing an evaluation result to the operating mode selection module.

[0034] The second connection can be switched as an output or as an input based on an evaluation result from the COM-IF acquisition module.

[0035] In one embodiment, the transmitting module is designed to generate the analog differential signals in a first communication phase of the message with a different physical layer than in a second communication phase, when using one of the two communication standards.

[0036] The two communication standards CAN XL and 10BASE-T1 S are optional. The previously described transceiver can be part of a subscriber station for a serial bus system. The subscriber station can also be a communication control unit for managing communication within the bus system and generating the transmit signal. The subscriber station can be configured for communication within the bus system in such a way that, at least temporarily, exclusive, collision-free access to the bus system's bus is guaranteed for a subscriber station.

[0037] At least two of the previously described transmit / receive devices can be part of a gateway for forwarding messages between at least a first bus system and a second bus system, wherein one of the at least two transmit / receive devices of the gateway is connected to the first bus system and another of the at least two transmit / receive devices is connected to the second bus system.

[0038] The aforementioned problem is further solved by a method for communication with differential signals in a serial bus system with the features of claim 16. The method is carried out with a transmit / receive device for a subscriber station of the bus system, which has a transmit module, a receive module, a first terminal, a second terminal, and a COM-IF detection module, wherein the method comprises the steps of receiving, at the first terminal, a digital transmit signal from a communication control device, wherein the transmit signal is configured for transmission as an analog differential signal to a bus of the bus system in order to send a message to at least one other subscriber station of the bus system; evaluating, with the COM-IF detection module, whether the digital transmit signal at the first terminal has at least one predetermined property of a communication standard of two communication standards.for which the transmit module and the receive module are designed for communication in the serial bus system, switching the transmit / receive device based on the evaluation of the COM-IF acquisition module into one of the two communication standards, transmitting, with the transmit module, the transmit signal as an analog differential signal onto the bus according to the set communication standard, and / or receiving, with the receive module, analog differential signals from the bus to output a digital receive signal according to the set communication standard to the communication control unit.

[0039] The method offers the same advantages as previously mentioned in relation to the transmitting / receiving equipment.

[0040] Furthermore, the described transmit / receive device also performs a method for setting the transmit / receive device to one of two communication standards for communication with differential signals in a serial bus system in the procedure for communication with differential signals in a serial bus system.

[0041] Other possible implementations of the invention also include combinations of features or embodiments described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In such cases, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0042] Drawings

[0043] The invention is described in more detail below with reference to the accompanying drawing and by means of exemplary embodiments. The drawing shows:

[0044] Fig. 1 shows a simplified block diagram of a gateway with bus systems according to a first embodiment;

[0045] Fig. 2 is a diagram illustrating the structure of a frame for a message that can be sent by a subscriber station of a bus system according to the first embodiment;

[0046] Fig. 3 shows a block diagram of a transmit / receive device of a subscriber station of the bus system of Fig. 1;

[0047] Fig. 4 shows a block diagram of the transmit / receive device of Fig. 3 when the transmit / receive device is set for a first communication standard for differential signals on the bus with frame according to Fig. 2;

[0048] Fig. 5 shows a block diagram of the transmit / receive device of Fig. 3 when the transmit / receive device is set for a second communication standard for differential signals on the bus;

[0049] Figures 6 to 9 show an example of a time course of signals received by the transmit / receive device in the configuration of Figure 4 for a frame of Figure 2 or generated on the bus; Figure 10 shows another example of a time course of signals received by the transmit / receive device in the configuration of Figure 4 during an arbitration phase (SIC operating mode);

[0050] Fig. 11 shows the time course of the bus signals CAN_H, CAN_L, which are sent to the bus by the transmit / receive device of Fig. 4 due to the transmit signal of Fig. 10;

[0051] Figures 12 to 15 show an example of the time course of signals received by the transmit / receive device in the configuration of Figure 5 or generated on the bus; and

[0052] Fig. 16 shows the time course of a reset signal received by the transmit / receive device in the configuration of Fig. 5.

[0053] In the figures, identical or functionally equivalent elements are provided with the same reference symbols unless otherwise specified.

[0054] Description of the exemplary implementations

[0055] Fig. 1 shows a first bus system 1 and a second bus system 1A, which are connected to each other via a gateway 5. However, the gateway 5 can be connected to more than two bus systems 1 and 1A, although this is not shown in the figures.

[0056] The first bus system 1 can, for example, be at least partially a CAN bus system, such as a Classical CAN bus system, a CAN FD bus system, a CAN XL bus system, etc., according to the international standard ISO 11898-1:2024. The second bus system 1A can, for example, be at least partially a 10BASE-T1 S bus system according to the international standard IEEE 802.3cg™. However, the bus systems 1 and 1A are not limited to this. In particular, the bus systems 1 and 1A can be configured to operate according to the same communication standard. The bus systems 1 and 1A can be used in a vehicle, especially a motor vehicle, an aircraft, etc., or in a hospital, etc.

[0057] Although the bus systems 1 , 1 A are described below using CAN bus systems and 10BASE-T1 S-bus systems, none of the bus systems 1 , 1 A are limited to this. Alternatively, at least one of the bus systems 1 , 1 A can be another serial bus system 1 that uses differential signals in particular.

[0058] In Fig. 1, the bus system 1 has a plurality of participant stations 10, 20, 30, which, like the gateway 5, are each connected to a bus 40 or bus line with a first bus wire 41 and a second bus wire 42. In a CAN bus system, the bus wires 41 and 42 can also be called CANH and CANL for carrying signals CAN_H and CAN_L on the bus 40. The bus wires 41 and 42 together form the bus line for the bus 40.

[0059] In the example shown in Fig. 1, bus system 1A has a subscriber station 50, which, like gateway 5, is connected to a bus 40A or bus line with a first bus wire 41A and a second bus wire 42A. In a 10BASE-T1 S-bus system 1A, the bus wires 41A and 42B are called LINE+ and LINE-, respectively. The bus wires 41A and 42B together form the bus line for bus 40A.

[0060] Messages 45, 46, and 47, in the form of signals, can be transmitted via the first bus 40 between the individual participant stations 10, 20, and 30 and the gateway 5. Messages 48, in the form of signals, can be transmitted via the second bus 40A between participant station 50 and the gateway 5. The gateway 5 can convert messages 45, 46, and 47 into the required communication standard and forward them to bus 40A, and / or forward a message 48 to bus 40. The participant stations 10, 20, 30, and 50 are, for example, control units or display devices of a motor vehicle.

[0061] As shown in Fig. 1, the subscriber stations 10, 30 each have a communication control unit 11 and a transmit / receive unit 12. The transmit / receive unit 12 has a transmit module 121 and a receive module 122.

[0062] The subscriber station 20 has a communication control unit 21 and a transmit / receive unit 22. The transmit / receive unit 22 has a transmit module 221 and a receive module 222.

[0063] The subscriber station 50 has a communication control unit 11 A and a transmit / receive unit 12. The transmit / receive unit 12 also has a transmit module 121 and a receive module 122, although this is not shown in Fig. 1.

[0064] The transmit / receive equipment 12 of subscriber stations 10 and 30, and the transmit / receive equipment 22 of subscriber station 20, are each directly connected to bus 40, even though this is not shown in Fig. 1. The same applies to the transmit / receive equipment 12 of subscriber station 50 with respect to bus 40A.

[0065] The communication control units 11 and 21 each serve to control communication between the respective subscriber stations 10, 20, and 30 via bus 40 and at least one other subscriber station of subscriber stations 10, 20, and 30 that is connected to bus 40. The same applies to the communication control unit 11A of subscriber station 50 with respect to bus 40A.

[0066] The communication control unit 11 creates and reads initial messages 45 and 47, which are, for example, modified CAN messages 45 and 47. These modified CAN messages 45 and 47 are based, for example, on the CAN XL format. The transmit / receive unit 12 is used to send and receive messages 45 and 47 from bus 40. The transmit module 121 receives a digital transmit signal TxD generated by the communication control unit 11 for one of the messages 45 and 47 and converts it into signals for transmission on bus 40. The digital transmit signal TxD can be a pulse-width modulated signal, at least temporarily or in sections. The receive module 122 receives signals transmitted on bus 40 corresponding to messages 45 to 47 and generates a digital receive signal RxD from them.

[0067] The receiver module 122 sends the receive signal RxD to the communication control unit 11.

[0068] Additionally, the communication control unit 11 can be configured to create and read second messages 46, which are, for example, CAN FD messages 46. The transmit / receive unit 12 can be configured accordingly.

[0069] The communication control unit 11 A is described in more detail with reference to Fig. 5.

[0070] The communication control unit 21 of Fig. 1 can be implemented like a conventional CAN controller according to ISO 11898-1:2015, i.e., like a CAN FD-tolerant Classical CAN controller or a CAN FD controller. The communication control unit 21 creates and reads secondary messages 46, for example, CAN FD messages or Classical CAN messages. The transmit / receive unit 22 is used to send and receive the messages 46 from the bus 40. The transmit module 221 receives a digital transmit signal TxD created by the communication control unit 21 and converts it into signals for a message 46 on the bus 40. The receive module 222 receives signals transmitted on the bus 40 corresponding to messages 45 to 47 and generates a digital receive signal RxD from them. The transmit / receive unit 22 may be implemented like a conventional CAN FD transceiver or CAN SIC transceiver.

[0071] To send messages 45, 46, 47 to bus 40 using CAN SIC or CAN XL, proven features are adopted that contribute to the robustness and user-friendliness of CAN and CAN FD, in particular the frame structure with identifier and arbitration according to the well-known CSMA / CR method. The CSMA / CR method necessitates the existence of so-called recessive states on bus 40, which can be overwritten by other participating stations 10, 20, 30 with dominant levels or states on bus 40. With the two participating stations 10 and 30, the generation and subsequent transmission of messages 45 and 47 using various CAN formats, especially the Classical CAN format, the CAN FD format, or the CAN XL format, as well as the reception of such messages 45 and 47, is possible. This is described in more detail below for message 45.

[0072] If no communication takes place on bus 40, at least one of the participant stations 10, 20, 30, in particular their communication control unit 11, 21, can be put into a sleep mode. This saves energy.

[0073] In CAN XL, the subscriber station 10, 30 switches its transmit / receive device 12 to a SLOW or SIC operating mode in order to participate in communication on the bus 40. In SLOW or SIC operating mode, the subscriber station 10, 30 can participate in an arbitration between the subscriber stations 10, 20, 30 of the bus system 1 during an arbitration phase 451 (first communication phase) of a frame from Fig. 2.

[0074] Fig. 2 shows a frame 450 for message 45, which is in particular a CAN XL frame, as provided by the communication control unit 11 to the transmit / receive unit 12 for transmission on bus 40. In this embodiment, the communication control unit 11 creates the frame 450 as compatible with CAN FD. Alternatively, the frame 450 is compatible with any successor standard for CAN FD. The frame 450 has a maximum duration T_450, which corresponds to a predetermined maximum frame length.

[0075] According to Fig. 2, the frame 450 for CAN communication on bus 40 is divided into different communication phases 451 and 452, namely an arbitration phase 451 (first communication phase) and a data phase 452 (second communication phase). Following a start bit SOF, the frame 450 has an arbitration field 453, a control field 454, a first switching field 455, a data field 456, a checksum field 457, a second switching field 458, and a frame termination field 459. The checksum field 457, the second switching field 458, and the frame termination field 459 form a frame termination phase 457, 458.

[0076] 459 of the frame 450.

[0077] In arbitration phase 451, an identifier (ID) in the arbitration field 453 is used to negotiate bitwise between participating stations 10, 20, and 30 which station wants to send the message 45, 46 with the highest priority and therefore receives exclusive access to bus 40 of bus system 1 for sending in the subsequent data phase 452. A physical layer, similar to that used in CAN, CAN FD, or CAN SIC, is employed in arbitration phase 451. This physical layer corresponds to the physical layer, or layer 1, of the well-known OSI model (Open Systems Interconnection model).

[0078] During phase 451, the well-known CSMA / CR protocol is used, which allows simultaneous access to bus 40 by participant stations 10, 20, and 30 without destroying the higher-priority message 45 or 46. This makes it relatively easy to add further bus participant stations 10, 20, and 30 to bus system 1, which is very advantageous.

[0079] The CSMA / CR protocol necessitates the existence of recessive states on bus 40, which can be overridden by other participant stations 10, 20, 30 with dominant levels or states on bus 40. In the recessive state, high impedance conditions prevail at individual participant stations 10, 20, 30, which, in combination with the parasitic effects of the bus circuitry, results in longer time constants. This limits the maximum bit rate of today's CAN FD physical layer to approximately 2 megabits per second in real-world vehicle applications.

[0080] At the end of the arbitration phase 451, the first switching field 455 switches to the operating mode for the data phase 452. With CAN-XL, the subscriber station 10, 30, in particular its transmit / receive unit 12, which won the arbitration and is therefore the sender of the frame 450 in the data phase 452, switches to a FAST_TX operating mode. However, with CAN XL, the subscriber station 10, 30, in particular its transmit / receive unit 12, which lost the arbitration and is therefore only the receiver of the frame 450 in the data phase, switches to a FAST_RX operating mode.

[0081] In data phase 452, in addition to part of the first switching field 455, the payload data of the CAN-XL frame 450 or message 45 from data field 456, as well as the checksum field 457 and part of the second switching field 458, are sent. At the end of data phase 452, the second switching field 458 switches back to arbitration phase 451.

[0082] A sender of message 45 only begins sending bits of data phase 452 to bus 40 when the subscriber station 10, as the sender, has won the arbitration and thus has exclusive access to bus 40 of bus system 1 for sending.

[0083] Thus, in the arbitration phase 451, the participating stations 10 and 30 partially use a format known from CAN / CAN-FD according to ISO 11898-1:2015, particularly up to and including the FDF bit. However, compared to CAN or CAN FD in the data phase 452, the second communication phase, an increase in the net data transmission rate to over 10 megabits per second, specifically 20 Mbit / s, is possible. Furthermore, increasing the size of the payload per frame, particularly to approximately 2 kilobytes or any other value, is possible.

[0084] Fig. 3 shows the transceiver 12 in more detail, which can be used for one of the subscriber stations 10, 30. The transceiver 12 has a TXD / TX connection for a transmit signal from Fig. 6, Fig. 10, or Fig. 12, or the reset signal from Fig. 16; an RXD / RX connection for a receive signal from Fig. 9 or Fig. 15; an STB / ED connection, in particular for a status signal; a CANH / LINE+ connection for the CAN_H or LINE+ signal; and a CANL / LINE- connection for the CAN_L or LINE- signal. Additionally, the transceiver 12 has connections for a power supply VCC, ground (GND), and VIO for an optional alternative power supply to the TXD / TX, RXD / RX, and STB / ED connections. However, the number of connections of the transmit / receive device 12 is not limited to the stated number of 8 connections. Instead, the number of connections can be chosen as needed.

[0085] The transmit / receive device 12 also has the transmit module 121, the receive module 122, an operating mode selection module 123, and a communication interface acquisition module 124. The communication interface acquisition module 124 is hereinafter referred to as the COM-IF acquisition module 124.

[0086] The COM-IF acquisition module 124 has a test block 1241 for checking the status of the TXD / TX, STB / ED terminals and / or a signal at the respective TXD / TX, STB / ED terminal. Furthermore, the COM-IF acquisition module 124 has a decision block 1242 for determining which communication control unit 11, 11A is connected to the transmit / receive unit 12. The COM-IF acquisition module 124 thus performs an evaluation of the status, in particular the voltage level or resistance value, of the TXD / TX, STB / ED terminals and / or a signal at the respective TXD / TX, STB / ED terminal. This is described in more detail below.

[0087] The transmitter module 121 can be configured as a full bridge with four transmission stages, which are not shown in the figures. The transmitter module 121 has an internal resistance of 1211.

[0088] The COM-IF acquisition module 124 can be a digital component, specifically a discrete-time system. The COM-IF acquisition module 124 can be operated at a predetermined frequency suitable for testing the signal at the TXD / TX connector. Specifically, the frequency is greater than 400 MHz.

[0089] The transmitter / receiver 22 can be constructed in the same way as the transmitter / receiver 12. Therefore, the transmitter / receiver 22 is not described separately. In the transmitter / receiver 12, the voltage supply for the first and second bus wires 41, 42 is provided via the at least one VCC terminal. In particular, a voltage of 5 V or 3.3 V, or any other desired voltage, can be connected to the VCC terminal. The connection to ground, in particular CAN_GND, is implemented via the GND terminal.

[0090] The transceiver 12 can be connected to bus 40 via the CANH / LINE+ and CANL / LINE- connections, specifically its first bus wire 41 for CAN_H or CAN-XL_H or LINE+ and its second bus wire 42 for CAN_L or CAN-XL_L or LINE-. More precisely, the transceiver module 121 is connected at its output to the CANH / LINE+ and CANL / LINE- connections. Furthermore, the receiver module 122 is connected at its input to the CANH / LINE+ and CANL / LINE- connections.

[0091] The transmitter module 121 is connected at its input to the TXD / TX terminal for receiving a transmit signal TxD shown in Fig. 6 or Fig. 10 from the communication control unit 11 of Fig. 1, or for receiving a transmit signal Tx shown in Fig. 12 or Fig. 16. Furthermore, the transmitter module 121 is connected at its input to an output of the operating mode selection module 123, at which an operating mode selection signal B_SW containing information for selecting the operating mode to be switched is output.

[0092] The receiver module 122 is also connected at its input to the output of the operating mode selection module 123, at which the operating mode switching signal B_SW is output. A first output of the receiver module 122 is connected to the RXD / RX terminal for outputting a receive signal RxD, as shown in Fig. 9, to the communication control unit 11 of Fig. 1, or for outputting a receive signal Rx, as shown in Fig. 15. A second output of the receiver module 122 is connected to the STB / ED terminal. The operating mode selection module 123 of Fig. 3 is connected at a first input terminal to the TXD / TX terminal for receiving the transmit signal TxD or Tx, as described above. Furthermore, the operating mode selection module 123 of Fig. 3 is connected at a second input terminal to the output of the COM-IF acquisition module 124. In addition, the operating mode selection module 123 of Fig. 3 is connected to the STB / ED connection via a third input port.The output terminal of the operating mode selection module 123 is connected to the transmit module 121 and to the receive module 122, as previously described.

[0093] The COM-IF acquisition module 124 of Fig. 3 is connected at its first input to the TXD / TX port to receive the transmit signal TxD or Tx, as described previously. Additionally, the COM-IF acquisition module 124 of Fig. 3 is connected at its second input to the STB / ED port.

[0094] The COM-IF acquisition module 124 evaluates the input at the TXD / TX and STB / ED ports to determine whether the transmit / receive device 12 is connected to a communication control unit 11 (CAN-XL controller) or a communication control unit 11A (10BASE-T1 S controller) as shown in Fig. 5. The COM-IF acquisition module 124 outputs its evaluation result to the operating mode selection module 123.

[0095] The operating mode selection module 123 is designed to determine the current operating mode from the inputs at the TXD / TX and STB / ED terminals and the output of the module 124, namely, for example, SLEEP, SLOW or SIC, FAST_TX, FAST_RX for CAN XL or LOW_POWER, NORMAL, TRANSMITTING, CONFIG for 10BASE-T1 S.

[0096] Furthermore, the operating mode selection module 123 is designed to forward its determination result, i.e., the information about the operating mode, to modules 121 and 122 in the signal B_SW. Specifically, the operating mode selection module 123 uses the signal B_SW to switch the operating mode of the transmit module 121 and the operating mode of the receive module 122 according to the required communication standard for which the transmit / receive device 12 is to be used. This is described below with reference to Fig. 4 in relation to a CAN bus system 1 and with reference to Fig. 5 in relation to a 10BASE-T1 S-bus system 1A.

[0097] Fig. 4 shows that the transceiver 12 in a CAN bus system 1 is connected between the communication control unit 11 of Fig. 1 and a DC choke 13 for communication according to the CAN XL standard. The DC choke 13 is connected to the bus wires 41, 42 of the bus line for bus 40 via a line connector 15. The DC choke 13 is also called a common-mode choke (CMC). The bus wires 41, 42 can be configured as twisted pairs. The first and second bus wires 41, 42 are terminated with a terminating resistor 49. The terminating resistor 49 is an external load resistor for the transmitter module 121. As mentioned previously, the transmitter module 121 can be configured as a full bridge with four transmitter stages.The resistor 49 is connected in the bridge branch of the full bridge between the terminals CANH / LINE+ and CANL / LINE- of the transmit / receive device 12, more precisely of the transmit module 121, for the bus wires 41, 42.

[0098] Fig. 5 shows that the transceiver 12 is connected in a 10BASE-T1 S bus system 1A for communication according to the 10BASE-T1 S standard between the communication control unit 11 A and the DC choke 13. The DC choke 13 is connected to the line connector 15 and thus to the bus wires 41, 42 and the terminating resistor 49 via an AC decoupling module 14, in particular a decoupling capacitor. The communication control unit 11 A is designed to control communication according to the 10BASE-T1 S standard. The AC decoupling module 14 can also be called an AC decoupling module. Otherwise, the same applies to the transceiver module 121 as described with reference to Fig. 3 and / or Fig. 4.

[0099] As shown in Figs. 4 and 5, the RXD / RX and STB / ED connections of the transceiver 12 can be switched differently for use in bus systems 1 and 1A. Table 1 below shows an example of the types and functions of the individual connections (SO8 connector or SO8 pin) of the transceiver 12.

[0100] Table 1: Comparison of the type and function of the connections of the transmit / receive device 12 for CAN XL and 10BASE-T1 S

[0101] If the transceiver 12 is configured as shown in Fig. 4, the signals shown in Fig. 6 to Fig. 11 are received or generated at the terminals of the transceiver 12. The transceiver 12 can be switched to different operating modes: SLEEP, SLOW or SIC, FAST_TX, FAST_RX, as specified in the international standard ISO 11898-1:2024 for CAN.

[0102] Fig. 6 shows an example of the time course of a digital transmit signal TxD, which the transmit / receive device 12 receives serially from the communication control device 11 for a frame 450 of Fig. 2. The transmit signal TxD is divided over time t into the two communication phases 451 and 452, as described previously.

[0103] In the first communication phase (arbitration phase) 451, the transmitted signal TxD has bits with a bit time t_bt1 and the two distinct states Hl (high), in particular 1, and LW (low), in particular 0. In the second communication phase (data phase) 452, the transmitted signal TxD is at least temporarily a pulse-width modulated signal with a bit time t_bt2 and the two distinct states LVO, LV1. The bit time t_bt2 is shorter than the bit time t_bt1.

[0104] As shown in Fig. 6, the transmitter / receiver 12, like the transmitter / receiver 22, uses a first physical layer 451_P in the first communication phase (arbitration phase) 451 to send the transmit signal TxD from Fig. 6 as differential bus signals CAN_H, CAN_L according to Fig. 7 to the bus 40. The physical layer 451_P of the transmitter / receiver 12 has the operating mode SLOW or SIC, as described in more detail above and below.

[0105] However, in the second communication phase (data phase) 452, the transmit / receive device 12 according to Fig. 6 can use a second physical layer 452_P, which differs from the first physical layer 451_P, to send the transmit signal TxD from Fig. 6 as differential bus signals CAN_H, CAN_L according to Fig. 7 to the bus 40. The physical layer 452_P has two operating modes for the transmit / receive device 12, namely FAST_TX and FAST_RX, as described in more detail above. As shown in Fig. 7, the signals CAN_H and CAN_L are serial analog signals and alternately have at least one dominant state 401 and / or at least one recessive state 402. In the dominant state 401, U = VCAN_H = 3.5 V and U = VCAN_L = 1.5 V. In the recessive state 402, U = VCAN_H = VCAN_L = 2.5 V. A dominant state 401 (dorn) is driven in phase 451 when the transmit signal TxD is NRZ-encoded and TXD = 0 or LW (LOW).A recessive state 402 (rec) is generated, or occurs in phase 451 during NRZ encoding of the transmit signal TxD, when TXD = 1 or Hl (HIGH = High) applies.

[0106] After the arbitration in arbitration phase 451, one of the participating stations 10, 20, 30 is determined as the winner. If the respective participating station 10, 30 recognizes the signal in the first switching field 455 of Fig. 2 for the switch from the first to the second communication phase 451, 452, the associated transmit / receive device 12 switches its physical layer 451_P to the physical layer 452_P of the data phase 452 at the end of the arbitration phase 451, as described previously.

[0107] As shown in Fig. 7, the transmitter module 121 then generates the states L0 or L1 sequentially and thus serially with the physical layer 452_P for the signals CAN_H, CAN_L on bus 40 in the data phase 452 or in the second operating mode (FAST_TX), depending on the transmit signal TxD from Fig. 6. The state L0 (VCAN_H = 3.0 V, VCAN_L = 2.0 V) is driven by a pulse width modulation (PWM encoding) of the transmit signal TxD for a first PWM symbol in the transmit signal TxD. The state L1 (VCAN_H = 2.0 V and VCAN_L = 3.0 V) is driven in the transmit signal TxD for a second PWM symbol LV1, which differs from the first PWM symbol LVO, during pulse width modulation (PWM coding) of the transmit signal TxD.

[0108] The frequency of the signals CAN_H and CAN_L can be increased in data phase 452 according to the transmit signal TxD. In the example shown in Figures 6 and 7, the bit time or bit duration t_bt2 in data phase 452 is shorter than the bit time or bit duration t_bt1 in arbitration phase 451. Therefore, the net data transmission rate in data phase 452 is increased in the example shown in Figures 6 and 7 compared to arbitration phase 451. In contrast, for example, the transmit / receive device 12 of the subscriber station 30 switches its Physical Layer 451_P at the end of the arbitration phase 451 from the first operating mode (SLOW or SIC) to the Physical Layer 452_P of the data phase 452 for the third operating mode (FAST_RX) of the transmit / receive device 12, if the subscriber station 30 is only a receiver, i.e., not a sender, of the frame 450 in the data phase 452.

[0109] If the transmit / receive device 12, in particular via the signaling in the second switching field 458 of Fig. 2, detects that a switch from the data phase 452 back to the arbitration phase 451 is required, the transmit / receive device 12 switches from transmitting (operating mode FAST_TX) and / or receiving (operating mode FAST_RX) signals with the physical layer 452_P to transmitting and / or receiving signals with the physical layer 451_P. Thus, all transmit / receive devices 12 switch their operating mode to the first operating mode (SLOW or SIC) after the end of the data phase 452. Therefore, all transmit / receive devices 12 can not only switch between the bit times t_bt1 and t_bt2, but also switch their physical layer, as described above.

[0110] According to Fig. 8, in the arbitration phase 451, an ideal differential signal VDIFF = CAN_H - CAN_L forms on bus 40 over time t, with values ​​of VDIFF = 2V for dominant states 401 (dorn) and VDIFF = 0V for recessive states 402 (rec). The VDIFF waveform in phase 451 is shown on the left side of Fig. 8. In contrast, in the data phase 452, a differential signal VDIFF = CAN_H - CAN_L forms on bus 40 over time t, corresponding to states L0 and L1 from Fig. 7, as shown on the right side of Fig. 8. State L0 has a value VDIFF = 1V. State L1 has a value VDIFF = -1V.

[0111] The receiver module 122 can distinguish between states 401 and 402 using any two of the receive thresholds T1, T2, and T3, which lie within the ranges TH_T1, TH_T2, and TH_T3. For this purpose, the receiver module 122 evaluates the signals from Fig. 7 or Fig. 8 at time t_A, as shown in Fig. 8. During the arbitration phase 451, the receiver module 122 uses the receive threshold T1 of, for example, 0.7 V and the receive threshold T2 of, for example, -0.35 V to evaluate the signals from Fig. 7 or Fig. 8. In contrast, during the data phase 452, the receiver module 122 only evaluates signals with the receive threshold T3. When switching between the first to third operating modes (SLOW or SIC, FAST_TX, FAST_RX), which were previously described with reference to Fig. 6, the receiver module 122 switches the receive thresholds T2, T3 in each case.

[0112] The reception threshold T2 is used to detect whether bus 40 is free when the subscriber station 12 is newly connected to the communication on bus 40 and attempts to integrate itself into the communication on bus 40.

[0113] Upon receiving the corresponding signals from bus 40, each transmit / receive device 12 generates the associated receive signal RxD, as shown in Fig. 9. Ideally, the receive signal RxD of Fig. 9 has no time offset from the transmit signal TxD of Fig. 6.

[0114] Fig. 10 shows an example of a portion of the digital transmit signal TxD, which the transmit module 121 receives from the communication control unit 11 during the arbitration phase 451, and from which it generates the signals CAN_H and CAN_L for the bus 40. In Fig. 10, the transmit signal TxD changes from a state LW (Low) to a state Hl (High) and back to the state LW (Low).

[0115] As shown in more detail in Fig. 11, the transmitter module 121 generates the signals CAN_H and CAN_L for the bus wires 41 and 42 for the transmit signal TxD from Fig. 10, such that an additional state 403 (sic) is present. The state 403 (SIC) can have different durations, as shown by state 403_0 (SIC) during the transition from state 402 (rec) to state 401 (dorn) and state 403_1 (sic) during the transition from state 401 (dorn) to state 402 (rec). State 403_0 (sic) is shorter in duration than state 403_1 (sic). To generate signals according to Fig. 11, the transmitter module 121 is switched to SIC mode.

[0116] The passage through the short sic state 403_0 is not required in the CiA610-3, and the state depends on the implementation. The duration of the "long" state 403_1 (sic) is specified for both CAN-SIC and the SIC operating mode in CAN-XL as t_sic < 530 ns, starting with the rising edge of the transmit signal TxD in Fig. 10.

[0117] In the "long" state 403_1 (SIC), the transmitter module 121 is designed to match the impedance between bus conductors 41 (CANH) and 42 (CANL) as closely as possible to the characteristic impedance Zw of the bus line used. Here, Zw = 1000 hm or 1200 hm. This matching prevents reflections and thus allows operation at higher bit rates. For simplicity, the following text will always refer to state 403 (sic) or sic-state 403.

[0118] The transmitter module 121 can be used to generate signals for bus 40 for the following CAN types: CAN-FD, CAN-SIC and CAN-XL.

[0119] Table 1: CAN types for transmitter module 121

[0120] Therefore, the transmitter module state 403 (sic) can be generated not only with CAN-SIC or CAN-XL (xl_sic). It can also be generated with CAN-FD. However, in CAN-FD, the time for the transmitter module state 403 (sic) can be shorter than with CAN-SIC or CAN-XL. Thus, the transmitter module 121 can generate two different bus states with CAN-FD, three different bus states with CAN-SIC, and five different states with CAN-XL.

[0121] When the transceiver 12 is configured as shown in Fig. 5, the signals shown in Fig. 12 to Fig. 15 are received or generated at the terminals of the transceiver 12. The transceiver 12 can be switched between different operating modes: LOW-POWER, NORMAL, TRANSMITTING, and CONFIG, as specified in the international standard IEEE 802.3cg™ for 10BAS ET 1 S.

[0122] Fig. 12 shows an example of a time course of a digital transmit signal Tx, which the transmit / receive device 12 receives from the communication control device 11 A of Fig. 5 in order to send the transmit signal Tx as differential bus signals LINE+, LINE- according to the 10BASE-T1 S standard to the bus 40A of the bus system 1 A;

[0123] According to Fig. 12, the transmitted signal Tx is divided over time t into several communication phases 460, 461, 462, which are assigned to the individual subscriber stations 10, 20, 30 by a master subscriber station for transmission. In communication phases 460 and 462, the transmit / receive device 12, specifically its transmit module 121 and receive module 122, is in NORMAL mode. In communication phase 461, the transmit / receive device 12 is permitted to transmit on bus 40A. Therefore, in phase 461, the transmitting mode is activated for the transmit / receive device 12, specifically its transmit module 121 and receive module 122. The transmission permission is allocated according to a round-robin algorithm, in which each participating station receives a transmission time slot in a transmission cycle, so that collisions on bus 40 can be avoided.In communication phases 460, 461, 462, the transmit signal Tx has bits with a bit time t_bt and the two different states Hl (high), in particular 1, and LW (low), in particular 0.

[0124] As shown in Fig. 13, the transmit / receive device 12 sends the transmit signal Tx from Fig. 12 as serial analog signals LINE+, LINE- to bus 40A. The signals alternately have at least one state VO, also called VLINE_POS, and / or at least one state V1, also called VLINE_NEG.

[0125] According to Fig. 14, a differential signal V_L forms on bus 40A over time t in the ideal case. For state VO, U = V_L (VO) = ​​+0.5 V. For state V1, U = V_L (V1) = -0.5 V.

[0126] The receiver module 122 can distinguish the states VO and V1 using any two of the reception thresholds T1_ETH, T2_ETH, and T3_ETH, which lie in the ranges TH_T1, TH_T2, and TH_T3. For this purpose, the receiver module 122 samples the signals from Fig. 13 or Fig. 14 at predetermined times. To evaluate the sampling result, the receiver module 122 uses all three reception thresholds T1_ETH, T2_ETH, and T3_ETH in NORMAL and TRANSMITTING modes. In contrast, in LOW-POWER mode, the receiver module 122 uses only the two reception thresholds T2_ETH and T3_ETH. The receive threshold T1_ETH typically has a value of 0.0 V, the receive threshold T2_ETH typically has a value of +0.15 V, and the receive threshold T3_ETH typically has a value of -0.15 V. When switching between the operating modes (NORMAL, TRANSMITTING, LOW-POWER) previously described with reference to Fig. 6, the receive module 122 switches the receive thresholds T1_ETH, T2_ETH, and T3_ETH as required.

[0127] Upon receiving the corresponding signals from bus 40, each transmit / receive device 12 generates the associated receive signal Rx, as shown in Fig. 15. Ideally, the receive signal Rx has no time offset from the transmit signal Tx.

[0128] To set the configuration of the transmitting / receiving device 12 according to Fig. 4 or according to Fig. 5, the transmitting / receiving device 12 proceeds as described below.

[0129] After the supply voltage is switched on at the VCC terminal, also known as power-up, the transmitter module 121 remains in a high-impedance state on the bus side, if possible. "High-impedance state" here means that the resistance value of the internal resistor 1211 in the transmitter module 121 is set to a value at least as high as the resistance value of the bus termination resistor 49. This ensures that the bus 40, 40A is not blocked with potentially incorrect symbols.

[0130] The transmitter module 121 remains in the high-impedance state on the bus side until it is certain, by checking the criteria described below, whether a communication control device 11 is connected to the inputs of the transmitter / receiver device 12, so that the device 12 should behave according to the CAN, in particular CAN-XL, standard, or whether a communication control device 11 A is connected, so that the device 12 should behave according to the 10BASE-T1 S standard.

[0131] The COM-IF acquisition module 124 forwards the respective decision as an evaluation result to the operating mode selection module 123.

[0132] Once the testing and / or evaluation is completed with modules 123, 124, in particular a decision is made or has been made regarding the communication standard, the transmitting / receiving device 12 behaves according to the corresponding communication standard.

[0133] However, the transmit / receive device 12 is designed to further check and / or evaluate at least one of the following criteria for plausibility. This ensures that any faults, such as a short circuit at the STB / ED and / or TX / TXD connection, are detected. The criteria for identifying the interface for the transmit / receive device 12 are as follows:

[0134] First criterion (TX edges at STB / ED = HIGH)

[0135] Module 124 is designed to check whether the STB / ED connection is in the HIGH state (Hl) and whether edges are being received at the TXD / TX connection. If the STB / ED connection is in the HIGH state (Hl) and edges are being received at the TX connection, module 124 determines that the connected communication control unit is a 11A communication control unit for 10BASE-T1 S. This is because equivalent behavior for CAN-XL does not exist.

[0136] Additionally or alternatively, module 124 is configured to check, for the first criterion, whether a state LW (low) is signaled at the STB / ED connection of the transmitter / receiver 12. If a state LW (low) is signaled at the STB / ED connection of the transmitter / receiver 12, module 124 determines that the connected communication control unit is a communication control unit 11 for CAN XL. This is because a communication control unit 11 for CAN in CAN-XL signals the switching of the operating mode from standby to low, normal, or SIC by a state LW (low) at the STB / ED connection of the transmitter / receiver 12.

[0137] Second criterion (Periodic reset commands R_ST (RESET commands) after power-up)

[0138] Module 124 is designed to check whether reset commands RS_C, as shown in Fig. 16, are periodically sent at the TXD / TX terminal. These commands are intended to reset the transceiver 12 from its initial LOW_POWER state to the NORMAL state according to the 10BASE-T1 S protocol. In the 10BASE-T1 S standard, a reset command R_C is instead called a RESET command. The lower part of Fig. 16 shows the state of a variable CMD over time t, which is determined by the signal waveform at the TXD / TX terminal over time t. "CMD" is an internal variable of a digital section of the transceiver 12. This digital section can, for example, be part of module 123 and / or module 124. The value of the variable CMD is adjusted according to the signal at TX, more precisely based on the signal waveform at the TXD / TX terminal over time t. The value of the variable CMD is used for navigating the internal states.In other words, the value of the variable CMD is used to determine and / or transition between the internal states: NORMAL, TRANSMITTING, LOW_POWER, LOW_POWER_WAKE, and CONFIGURATION. In the example shown in Fig. 16, the variable CMD has two defined states: N_N and R_ST. In the 10BASE-T1 S standard, state N_N is called NONE, and state R_ST is called RESET. State R_ST of the variable CMD means that a reset command has been detected at the TXD / TX terminal. State N_N means that no reset command has (yet) been detected at the TXD / TX terminal. The shaded states represent undefined states or states irrelevant in this context.

[0139] According to Fig. 16, a reset command RS_C maintains the state Hl (high) for a duration ttxda of at least 20 ns, and then typically the state LW (low) for a duration ttxrst = 80 ns. This is followed by a period of Hl (high) of at least 20 ns, tcgap. The duration tcgap is intended to bridge the gap between RS_C reset commands. After such a reset command RS_C, the communication control unit 11A waits for the transceiver 12 to pull or switch the STD / ED pin to the state LW (low) to indicate that the transceiver 12, configured for 10BASE-T1 S, is ready to wake up.

[0140] Module 124 thus evaluates whether, after power-on of the transceiver 12, at least one RS_C reset command as shown in Fig. 16 is sent at the TXD / TX terminal, and whether the transceiver 12 or the device 11A then pulls the STD / ED terminal to the LW (LOW) state. During the time it takes for the transceiver 12 or the device 11A to pull the STD / ED terminal to the LW (LOW) state, further RS_C reset commands may periodically arrive at the TXD / TX terminal, sent by a communication control device 11A. The frequency of these pulses (RS_C reset commands) is not explicitly defined and is left to the manufacturer's discretion.

[0141] Furthermore, module 124 evaluates whether the RS_C reset commands at the TXD / TX connector are spaced more than 245 ns apart. If the RS_C reset commands are spaced further than 245 ns apart, module 124 determines that the connected communication control unit is a 11A communication control unit for 10BASE-T1 S. This is because the maximum permissible symbol length for a PWM symbol LVO, LV1 in CAN XL is shorter than 245 ns, but a bit for state 401 (dorn) is 80 ns longer. The pattern checked by module 124 is therefore too long for a PWM symbol LVO, LV1, but 80 ns too short for a dominant bit 401 (dorn) in CAN-SIC operating mode.

[0142] Furthermore, module 124 evaluates whether the RS_C reset commands arrive at the TXD / TX terminal at intervals of < 245 ns. This evaluation takes into account that such a bit pattern can also represent CAN-XL PWM symbols. To rule this out, module 124 can wait for the maximum length of a CAN-XL frame 450, which corresponds to the duration T_450 in Fig. 2. If no arbitration bits with bit time t_bt1 are sent for the CAN-XL frame 450 after frame 450, module 124 decides that the connected communication control device is a communication control device 11 A for 10BASE-T1 S. Consequently, the transmit / receive device 12 pulls its STB / ED terminal to the state or voltage level LW (low) to switch to NORMAL mode according to the 10BASE-T1 S protocol.

[0143] Third criterion (minimum symbol length):

[0144] Module 124 is designed to check the length of the transmitted symbols or the bit time t_bt2 at the TXD / TX connector. If the symbol length is shorter than a predetermined time, in particular 45 ns or up to 49 ns, module 124 determines that the connected communication control unit is a communication control unit 11 A for 10BASE-T1 S. One reason for this is that 45 ns is the shortest permissible symbol time that, according to the CAN-XL standard, must be recognized as such by the transmit / receive unit 12. Another reason is that, according to the CAN-XL standard, the shortest permissible PWM symbols LVO, LV1, which are measured between two consecutive edges of the same polarity, have a nominal duration of 50 ns in the FAST operating modes FAST_TX, FAST_RX. This corresponds to a data transfer rate of 20 Mbit / s. In contrast, a DME0 symbol in the 10BASE-T1 S standard has a duration of only 40 ns.The COM-IF acquisition module 124, for example, is a digital component, specifically a discrete-time system. The COM-IF acquisition module 124 operates at a predetermined frequency f, which is suitable for testing the signal at the TXD / TX connector. Specifically, the frequency f is > 400 MHz.

[0145] This allows module 124 to reliably distinguish between symbol lengths of 40ns and 45ns by checking the third criterion. The difference, in particular 5ns, can thus be reliably distinguished by a sampling point.

[0146] Fourth criterion (Symbol Duty Cycle):

[0147] Module 124 is designed to check the duty cycle of incoming symbols at the TXD / TX connector.

[0148] In particular, module 124 is designed to check whether symbols with a duty cycle of approximately 50% are arriving. If the duty cycle of a symbol is approximately 50%, module 124 determines that the connected communication control unit is a communication control unit 11A for 10BASE-T1S. One reason for this is that, according to the 10BASE-T1S standard, a DME0 symbol transmitted at TX nominally consists of a 20ns HIGH state and a 20ns LOW state. This corresponds to a duty cycle of 50%. In contrast, CAN-XL controllers of unit 11A transmit PWM symbols LVO and LV1 with a nominal duty cycle of 25% (LVO symbol) and 75% (LV1 symbol), respectively.

[0149] Alternatively or additionally, module 124 can be configured to check at the TXD / TX connection whether the duty cycle of a symbol is greater than a predetermined first value, for example, 60%, or less than a predetermined second value, for example, 30%. If the duty cycle of a symbol is greater than the predetermined first value, for example, 60%, or less than the predetermined second value, for example, 30%, module 124 determines that the connected communication control unit is a CAN XL communication control unit 11. Naturally, under the aforementioned conditions for the duty cycle of the symbols, other values ​​for the predetermined first value and / or the predetermined second value can be selected.

[0150] This allows the COM-IF detection module 124 to reliably detect the duty cycle length of a symbol at the TXD / TX connector by checking the fourth criterion.

[0151] Depending on the results of the tests on the four criteria, the COM-IF acquisition module 124 decides which communication interface should be used by the transmit / receive device 12.

[0152] The COM-IF acquisition module 124 forwards the respective decision as an evaluation result to the operating mode selection module 123.

[0153] Second embodiment

[0154] According to a second embodiment, the COM-IF acquisition module 124 is designed to check at least one and up to three of the four criteria mentioned above.

[0155] Therefore, module 124 can make the decision as to which communication interface should be served by the transmit / receive device 12 using fewer than the four criteria mentioned above.

[0156] All previously described configurations of the transmit / receive device 12, the subscriber stations 10, 20, 30, the bus systems 1, 1A, the gateway 5, and the method executed in or by them according to the exemplary embodiments and their modifications can be used individually or in all possible combinations. In addition, the following modifications are particularly conceivable.

[0157] The bus systems 1, 1A described above, according to at least one of the embodiments, are described using a bus system based on the CAN protocol or 10BASE-T1S. However, the bus systems 1, 1A according to the embodiments can alternatively be a different type of communication network in which the signals are transmitted as differential signals.

[0158] It is advantageous, but not a necessary requirement, that in bus system 1, exclusive, collision-free access of a participant station 10, 20, 30 to bus 40 is guaranteed at least for certain periods of time.

[0159] The bus system 1 according to at least one of the embodiments and their modifications is, in particular, a bus system in which communication between at least two of the participant stations 10, 20, 30 is possible according to two different CAN standards, such as CAN-HS or CAN FD or CAN SIC or CAN XL. Thus, the functionality of the previously described embodiment can be used, for example, with transmit / receive devices 12, 22 that are to be operated in such a bus system.

[0160] The number and arrangement of the participant stations 10, 20, 30 in the bus system 1 according to at least one of the embodiments and their modifications can be selected arbitrarily.

Claims

Claims 1) Transmit / receive device (12) for a subscriber station (10; 30; 50) of a serial bus system (1 ; 1 A), comprising a transmit module (121) for sending a digital transmit signal (TxD; Tx) as an analog differential signal (CAN_H, CAN_L; LINE+, LINE-) to a bus (40; 40A) of the bus system (1 ; 1 A) in order to send a message (45; 48) to at least one other subscriber station (10; 20; 30) of the bus system (1 ; 1 A), and a receive module (122) for receiving signals (CAN_H, CAN_L; LINE+, LINE-) from the bus (40; 40A) and for generating a digital receive signal (RxD; Rx) from the analog differential signal (CAN_H, CAN_L; LINE+, LINE-), a first connection (TXD / TX) for receiving the transmit signal (TxD; Tx) from a communication control unit (11 ; 11 A), a second connection (RXD / RX) for outputting the digital receive signal (RxD; Rx) to the communication control unit (11 ;11 A), and a COM-IF acquisition module (124) for evaluating whether the digital transmit signal (TxD; Tx) at the first terminal (TXD / TX) has at least one predetermined property of a communication standard of two communication standards (CAN; 10BASE-T1 S), for which the transmit module (121) and the receive module (122) are designed for communication in the serial bus system (1 ; 1 A), wherein the transmit / receive device (12) for communication on the bus (40; 40A) is adjustable on the basis of the evaluation result of the COM-IF acquisition module (124). 2) Transmit / receive device (12) according to claim 1, further comprising a third connection (STB / ED) for setting one of two predetermined voltage levels (Hl; LW), wherein the COM-IF detection module (124) is further configured to evaluate whether the digital transmit signal (TxD; Tx) at the first connection (TXD / TX) occurs in combination with a predetermined voltage level of the two predetermined voltage levels (Hl; LW) at the third connection (STB / ED). 3) Transmitting / receiving device (12) according to claim 2, wherein the COM-IF detection module (124) is configured to evaluate, with respect to the presence of a first predetermined property of a communication standard of the two communication standards (CAN; 10BASE-T1 S), whether signal edges occur at the first terminal (TXD / TX) in combination with a predetermined first voltage level (Hl) of the two predetermined voltage levels (Hl; LW) at the third terminal (STB / ED). 4) Transmit / receive device (12) according to claim 2 or 3, wherein the COM-IF detection module (124) is configured to evaluate with respect to the presence of a second predetermined property of a communication standard of the two communication standards (CAN; 10BASE-T1 S), whether reset commands (RS_C) are periodically received at the first terminal (TXD / TX) in combination with a predetermined second voltage level (LW) of the two predetermined voltage levels (Hl; LW) at the third terminal (STB / ED). 5) Transmitting / receiving device (12) according to claim 4, wherein the COM-IF acquisition module (124) is configured to perform its evaluation with respect to the presence of the second predetermined property of one of the two communication standards (CAN; 10BASE-T1 S) only after the expiry of a time period (T_450) which corresponds to the maximum frame length of a frame (450) which is used for the message (45) when communicating with one The communication standard (CAN XL) uses two communication standards (CAN; 10BASE-T1 S). 6) Transmitting / receiving device (12) according to one of the preceding claims, wherein the COM-IF acquisition module (124) is configured to evaluate with respect to the presence of a third predetermined property of a communication standard of the two communication standards (CAN; 10BASE-T1 S), which minimum symbol length (t_bt2) of the transmit signal (TxD; Tx) is detected. 7) Transmitting / receiving device (12) according to one of the preceding claims, wherein the COM-IF detection module (124) is configured to evaluate with respect to the presence of a fourth predetermined property of a communication standard of the two communication standards (CAN; 10BASE-T1 S), which duty cycle of a symbol of the transmit signal (TxD; Tx) is detected. 8) Transmitting / receiving device (12) according to one of the preceding claims, further comprising an operating mode selection module (123) for selecting an operating mode of the transmitting module (121) and / or the receiving module (122) on the basis of an evaluation result of the COM-IF acquisition module (124). 9) Transmitting / receiving device (12) according to claim 8, wherein the operating mode selection module (123) is configured to also evaluate the transmit signal (TxD; Tx) at the first terminal (TXD / TX) and the voltage level at the third terminal (STB / ED) for the selection of the operating mode of the transmitting module (121) and / or the receiving module (122). 10) Transmitting / receiving device (12) according to claim 8 or 9, wherein the COM-IF acquisition module (124) is configured to further evaluate the transmitted signal (TxD; Tx) with respect to the at least one predetermined property after passing an evaluation result to the operating mode selection module (123). 11 ) Transmitting / receiving device (12) according to one of the preceding claims, wherein the second connection (RXD / RX) can be switched as an output or as an input based on an evaluation result of the COM-IF acquisition module (124). 12) Transmitting / receiving device (12) according to one of the preceding claims, wherein the transmitting module (121) is configured to generate the analog differential signals (CAN_H, CAN_L) in a first communication phase (451) of the message (45) with a different physical layer (451_P) than in a second communication phase (452) when using one communication standard (CAN XL) of the two communication standards (CAN; 10BASE-T1 S). 13) Transmitting / receiving device (12) according to any of the preceding claims, wherein the two communication standards are CAN XL and 10BASE-T1 S. 14) Subscriber station (10; 30; 50) for a serial bus system (1 ; 1 A), comprising a transmit / receive device (12) according to one of the preceding claims, and a communication control device (11 ; 11A) for controlling the communication in the bus system (1 ;1A) and for generating the transmit signal (TxD, Tx), wherein the subscriber station (10; 30; 50) is configured for communication in a bus system (1 ; 1 A) in which at least temporarily exclusive, collision-free access of a subscriber station (10; 30; 50) to the bus (40; 40A) of the bus system (1 ; 1 A) is ensured. 15) Gateway (5) for forwarding messages (45; 46; 47; 48) between at least a first bus system (1) and a second bus system (1A), with at least two transmit / receive devices (12) according to one of claims 1 to 13, wherein one of the at least two transmit / receive devices (12) of the gateway (5) is connected to the first bus system (1) and another of the at least two transmit / receive devices (12) is connected to the second bus system (1 A). 16) Method for communication with differential signals in a serial bus system (1 ; 1 A), wherein the method is carried out with a transmit / receive device (12) for a subscriber station (10; 30; 50) of the bus system (1 ; 1 A) comprising a transmit module (121), a receive module (122), a first port (TXD / TX), a second port (RXD / RX), and a COM-IF capture module (124), wherein the method comprises the steps, Receiving, at the first terminal (TXD / TX), a digital transmit signal (TxD; Tx) from a communication control device (11; 11A), wherein the transmit signal (TxD; Tx) is configured for transmission as an analog differential signal (CAN_H, CAN_L; LINE+, LINE-) to a bus (40; 40A) of the bus system (1; 1A) in order to send a message (45) to at least one other subscriber station (10; 20; 30; 50) of the bus system (1A), Evaluate, using the COM-IF acquisition module (124), whether the digital transmit signal (TxD; Tx) at the first terminal (TXD / TX) has at least one predetermined property of a communication standard of two communication standards (CAN; 10BASE-T1 S) for which the transmit module (121) and the receive module (122) are used for communication in the serial bus system (1 ; 1 A) are designed, Switching the transmit / receive device (12) based on the evaluation of the COM-IF acquisition module (124) into one of the two communication standards (CAN; 10BASE-T1 S), Sending, with the transmit module (121), the transmit signal (TxD; Tx) as an analog differential signal (CAN_H, CAN_L; LIN E+, LINE-) to the bus (40; 40A) according to the set communication standard, and / or Receiving, with the receiver module (122), analog differential signals (CAN_H, CAN_L; LINE+, LINE-) from the bus (40; 40A) to output a digital receive signal (RxD; Rx) according to the set communication standard to the communication control unit (11 ; 11 A).

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