Participant station for a bus system and methods for improving the fault robustness of a participant station of a bus system

Abstract

Participant station (10; 30; 50; 60) for a bus system (1; 2), with a transmitting / receiving device (13) for transmitting a signal via the bus system (1; 2) to another subscriber station and for receiving a signal via the bus system (1; 2), in which at least temporarily exclusive, collision-free access of a subscriber station (10, 20, 30, 50, 60) to a bus line (40) of the bus system (1; 2) is ensured, and a modification device (12; 14) for modifying the transmission characteristics of a transmit path (131) of the transmit / receive device (13) and / or the receiving characteristics of a receive path (132) of the transmit / receive device (13), wherein the modification device (14) comprises a transmitter output stage (150) for pre-distortion of the signal to be transmitted by the transmit / receive device (13) in order to prevent the bus level from settling on a transmit channel within one clock cycle (T S) of the signal to be sent, and / or wherein the modification device (12) is a receiver modification device for changing the detection time (TD) to the right in the eye diagram and the decision threshold (E) upwards in the eye diagram, wherein the transmitter output stage (150) for pre-distortion of the signal to be transmitted by the transmit / receive device (13) is designed such that it adapts the transmitter characteristics of the subscriber station (50; 60) depending on the section of a frame of the bus system (2).

Description

Technical field

[0001] The present invention relates to a participant station for a bus system and a method for improving the fault robustness of a participant station of a bus system, in which, in particular, the fault robustness during information transmission on a bus system is improved even under unfavorable conditions, such as those that may be present due to branches, faulty terminations, mismatches, or pinched cable routing in the bus system. State of the art

[0002] The CAN bus system has become widely used for communication between sensors and control units. With the CAN bus system, messages are transmitted using the CAN protocol, as described in the CAN specification in ISO 11898. More recently, techniques such as CAN-FD have been proposed, in which messages are transmitted according to the specification "CAN with Flexible Data-Rate, Specification Version 1.0" (source: http: / / www.semiconductors.bosch.de), etc. These techniques increase the maximum possible data rate beyond 1 Mbit / s by using a higher clock frequency in the data fields. This can generally come at the expense of transmission quality, for example, in the form of a higher bit error rate, depending on the bus topologies actually used.

[0003] Actual bus topologies typically deviate from the theoretical model in that reflections occur on the bus line at points where the line exhibits a characteristic impedance that differs from the theoretical value. Such points include, for example, branch connections, incorrect terminations, impedance mismatches, and pinched cable routing, which are often found in practical implementations such as spur lines, passive star points, etc. The resulting reflections lead to temporal crosstalk of states on the bus line, such that a transmitted symbol or bit can interfere with subsequent symbols, potentially distorting their detection.

[0004] According to the CAN specification in ISO 11898, the bus line should be terminated at both ends with the line impedance, so that transients decay within a transmitted symbol for the specified maximum cable length, resulting in a clear state at the end of the symbol interval. In reality, however, crosstalk between two or more CAN symbols is often unavoidable.

[0005] A participant station in a CAN bus system consists of a communication processor, usually integrated into a microcontroller, and a transmitter / receiver, also called a transceiver, which is typically a separate chip with a direct connection to the bus line. In such a transceiver, the receive path usually comprises only a comparator with upstream voltage dividers for bias adjustment, also known as bias matching, of the bus levels. The comparator directly evaluates the bus levels of dominant and recessive bit states and makes a decision at its output.

[0006] The transmit path consists of one pull-up and one pull-down transistor each for the two bus wires of the CAN bus system, also called CAN High (C_H) and CAN Low (C_L), which are used to couple the dominant levels during transmission. The recessive levels are established when both transistors are off, so that the input impedance of the receive path pulls the levels of the two bus wires to an average level. Due to the different internal resistances in the dominant and recessive states, arbitration of multiple subscriber stations on the bus system can be performed.

[0007] The transmission levels are set by the switching processes described above. Due to the primarily capacitive properties of the bus line in the bus system, a charging and discharging process takes place, meaning the desired bus levels are only reached after a certain time. The transition from dominant level to recessive level and from recessive level to dominant level occurs at different speeds or with different time constants.

[0008] These differing timings result in higher error probabilities in the receiving device, which can also be called a receiver, due to the slower transition from dominant to recessive bus levels. Since CAN-FD achieves an increase in data rate primarily by shortening the symbol duration in the data portion transmitted after arbitration, this characteristic could limit the application scenarios for the bus system.

[0009] In this case, the distance between the received signal and the decision threshold is greatly reduced, so that a superimposed noise disturbance is much more likely to lead to a false detection in the CAN transmit / receive device.

[0010] DE 4126850 A1 describes a circuit arrangement for adapting data bus controllers to a symmetrical bus line, particularly for the well-known CAN bus system in automotive applications. The particular advantage of the invention is the optimal limitation of the transmitted and received signal band values ​​at all data transmission rates, without interfering with the higher levels of the CAN protocol. A bus termination suitable for all waveforms of the bus signals (common mode = interference signal, differential mode = useful signal + interference component), which improves the signal-to-noise ratio, is also described, as is a current filter measure for limiting the particularly dangerous interference radiation affecting the vehicle's FM radio reception until internal filtering is implemented in the controller connection units.

[0011] Therefore, an implementation is desirable that achieves high signal quality for fast data phases without compromising the critical arbitration phase. Disclosure of the invention

[0012] Therefore, the object of the present invention is to provide a subscriber station for a bus system and a method that solve the aforementioned problems. In particular, a subscriber station for a bus system and a method are to be provided in which the transmission quality for information transmission on a bus system, which is in particular a CAN bus system, is improved even under the aforementioned unfavorable conditions of a real bus line.

[0013] The problem is solved by a subscriber station for a bus system with the features of claim 1. The subscriber station comprises a transmit / receive device for sending a signal via the bus system to another subscriber station and for receiving a signal via the bus system, whereby at least temporarily exclusive, collision-free access of a subscriber station to a bus line of the bus system is ensured, and a modification device for modifying the transmit characteristics of a transmit path of the transmit / receive device and / or the receive characteristics of a receive path of the transmit / receive device.

[0014] At the subscriber station, additional measures in the transmitting / receiving equipment are used to improve the signal on the bus line.

[0015] The participant station offers a significant advantage for the transition from dominant to recessive states, which also applies to CAN and potentially to FlexRay. The participant station is specifically suited to addressing the challenges of higher switching speeds in the data portion of CAN-FD.

[0016] Thus, the receiving station is also suitable for use in higher-frequency systems, such as CAN-FD, etc. The functionality of the receiving station with respect to the signal to be transmitted and / or the received signal can also be implemented in one embodiment, particularly as preprocessing in a transmit / receive device or transceiver, or a CAN transceiver, or a transceiver chipset. Specifically, it is possible for the functionality under consideration to be embedded either in the transceiver as a separate electronic component (chip) or in an integrated overall solution in which only one electronic component (chip) is present.

[0017] The receiving station is suitable for improving transmission quality during information transfer on a CAN bus system, even under the aforementioned unfavorable conditions of a real-world bus topology. The receiving station is also suitable for use in systems with higher clock speeds than a standard CAN bus system and can be implemented in the transmit and / or receive path of a transceiver, particularly a CAN transceiver chipset. Compared to currently available solutions, the receiving station features an additional processing stage for this purpose.

[0018] The modification device may include a transmitter output stage for pre-distortion of the signal to be sent by the transmit / receive device in order to achieve a settling of the bus level on a transmit channel within one clock cycle of the signal to be sent, and / or the modification device may be a receiver modification device for changing the detection time to the right in the eye diagram and the decision threshold upwards in the eye diagram.

[0019] The transmitter output stage can be designed to pre-distort the signal to be transmitted by the transmit / receive device in such a way that it adapts the transmitter characteristics of the receiving station depending on the section of a frame of the bus system. In this context, the transmitter output stage can be designed to pre-distort the data section of the signal to be transmitted by the transmit / receive device.

[0020] The transmitter output stage may be designed to pre-distort the signal to be transmitted by the transmitter / receiver by modifying the voltage level of the transmitted signal or the output resistance of the transmitter / receiver. In this context, the transmitter output stage may be designed to adjust both the voltage level and the output resistance depending on the time following a change in the state of the transmitted signal. Furthermore, this change in the state of the transmitted signal may, in particular, be a change from a dominant to a recessive state.

[0021] Preferably, the transmitter output stage comprises a first transistor, which can be driven by a first control signal, a second transistor, which can be driven by a second control signal, a third transistor, which can be driven by a third control signal, and a fourth transistor, which can be driven by a fourth control signal, wherein the first and second transistors are connected to a terminal for a first bus line, and wherein the third and fourth transistors are connected to a terminal for a second bus line. The transmitter output stage can be configured to drive the first to fourth transistors linearly in order to set a level with a defined internal resistance for the first and second bus lines.Alternatively or additionally, the transmitter output stage can be designed in such a way that it uses predetermined time profiles within each bit state for the first to fourth control signal to pre-distort the signal to be transmitted and the impedance of a transmission path of the transmitting / receiving device.

[0022] The previously described participant station can be part of a bus system that has a bus line and at least two participant stations which are connected to each other via the bus line (4) in such a way that they can communicate with each other. At least one of the at least two participant stations is a participant station as described above.

[0023] The aforementioned task is further solved by a method for improving the fault robustness of a participant station in a bus system. The method comprises the steps of transmitting a signal via the bus system to another participant station using a transmitter / receiver device of the participant station, or receiving a signal via the bus system using the transmitter / receiver device of the participant station, ensuring at least temporary exclusive, collision-free access of a participant station to a bus line of the bus system, and pre-distorting the signal to be transmitted by the transmitter / receiver device using a transmitter output stage of the participant station to achieve a settling of the bus level on a transmit channel within the clock frequency of the signal to be transmitted.

[0024] The procedure offers the same advantages as previously mentioned in relation to the participant station.

[0025] 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. Drawings

[0026] The invention is described in more detail below with reference to the accompanying drawing and by means of exemplary embodiments. The drawing shows: Fig. 1 a simplified block diagram of a bus system according to a first embodiment; Fig. 2 an electrical circuit diagram of a transmitting / receiving device of the bus system according to the first embodiment; Fig. 3 a signal waveform of a transmitted signal which is transmitted via the bus system according to the first embodiment, and a signal waveform of an associated control signal TX; Fig. 4 an idealized (standardized) signal waveform with exponentially decaying characteristic of the output stage of the transmitting / receiving device of Fig. 2 and a bus line of the bus system; Fig. 5. An example of an eye diagram corresponding to the signal pattern of Fig. 4; Fig. 6 a flowchart of a process according to the first embodiment; Fig. 7 a simplified block diagram of a bus system according to a second embodiment; Fig. 8 an electrical circuit diagram of a transmitting / receiving device of the bus system according to the second embodiment; Fig. 9 an electrical circuit diagram of a transmitter output stage of the transmit / receive device of the bus system according to the second embodiment; Fig. 10 a flowchart of a process according to the second embodiment Fig. 11 an example of a control signal for the transmitter output stage according to the second embodiment; Fig. 12 an example of a pre-distorted drive signal for the transmitter output stage according to the second embodiment; Fig. 13 a course of the output signals of the transmitter output stage according to the second embodiment for the signals of Fig. 11 and Fig. 12; and Fig. 14 An example of the structure of a message sent via the bus system.

[0027] In the figures, identical or functionally equivalent elements are provided with the same reference symbols unless otherwise specified. Description of the exemplary implementations

[0028] Fig. Figure 1 shows a bus system 1, which can be, for example, a CAN bus system, a CAN FD bus system, etc. The bus system 1 can be used in a vehicle, in particular a motor vehicle, an aircraft, etc., or in a hospital, etc.

[0029] In Fig. In bus system 1, there are multiple participant stations 10, 20, 30, each connected to a bus line 40 with a first bus wire 41 and a second bus wire 42. The bus wires 41 and 42 can also be called CAN High (C_H) and CAN Low (C_L) and serve to couple the dominant levels during transmission. Messages 45, 46, 47 in the form of signals can be transmitted between the individual participant stations 10, 20, 30 via bus line 40. The participant stations 10, 20, 30 can be, for example, control units or display devices of a motor vehicle.

[0030] As in Fig. As shown in Figure 1, participant stations 10 and 30 each have a communication control unit 11, a receiver modification unit 12, and a transmit / receive unit 13. Participant station 20, on the other hand, has a communication control unit 11 and a transmit / receive unit 14. The transmit / receive units 13 of participant stations 10, 20, and 30 are each directly connected to the bus line 40, even though this is shown in Figure 1. Fig. 1 is not shown.

[0031] The communication control unit 11 serves to control communication between each participant station 10, 20, 30 via bus line 40 and another participant station of the participant stations 10, 20, 30 connected to bus line 40. The receiver modification unit 12 serves to improve the reception quality of the message 45, 46, 47 received by the transmit / receive unit 13, as described in more detail later. The communication control unit 11 can be implemented like a conventional CAN controller. The transmit / receive unit 13 can be implemented like a conventional CAN transceiver with respect to its transmit functionality.

[0032] Fig. Figure 2 shows the structure of a transmit / receive device 13 of the subscriber station 20 in more detail as an example. The transmit / receive device 13 has a transmit path 131 and a receive path 132. The transmit path 131 is used to send a signal based on one of the messages 45, 46, or 47. The receive path 132 is used to receive the corresponding transmitted signal. The transmit path 131 and the receive path 132 are each configured as in a conventional CAN subscriber station.

[0033] In Fig. In the receive path 132, the transmit / receive device 13 has a first and second input terminal C_H, C_L for connecting the bus wires 41, 42. Also located in the receive path 132 are two resistors 133, 134, a comparator 135, a processing element 136, and an output terminal 137. Resistor 133 is connected between the first input of comparator 135, which is at positive potential, and the first input terminal C_H. Resistor 134 is connected between the second input of comparator 135, which is at negative potential, and the second input terminal C_L. In the transmit path 131, a pull-up transistor 138 and a pull-down transistor 139 are connected for the two bus wires 41, 42.

[0034] Fig. Figure 3 shows two signal waveforms over time, resulting from participant station 20. In the upper part of Fig. Figure 3 shows an example of a measured differential signal C_L-C_H between the bus wires 41 and 42 of the bus line 40. In the lower part of Fig. Figure 3 shows the corresponding control signal TX for transmit path 131. Besides the switching delay, the different time constants with which the desired bus level is established are particularly noticeable in the measured differential signal C_L-C_H. Consequently, the transition from dominant level to recessive level and from recessive level to dominant level occurs at different speeds or time constants. This is because the output resistance of the CAN transmit / receive device 13 depends on the transmit state of the signal being sent or the signal being sent.

[0035] In Fig. Figure 4 is an idealized signal waveform with an exponentially decaying characteristic of the transmitting / receiving device 13 and the bus line 40, shown over time normalized to the clock T. Sof the signal to be sent or the transmitted signal.

[0036] In the eye diagram of Fig. 5. It is evident that the distance of the received signal to the decision threshold E, which is in Fig. The signal strength is greatly reduced because the value at 0.5 in the middle of the vertical axis is significantly lower. This greatly increases the likelihood of a noise interference superimposed on the signal transmitted via bus line 40 leading to a false detection. Fig. 5 is the area usable for detection, shown hatched in the diagram.

[0037] To achieve the best possible fault robustness, the receiver modification device 12 modifies the reception characteristics of the transmit / receive device 13. This is in Fig. 5 shown, which is related to the in Fig. The procedures shown in section 6 for improving the fault robustness of a participant station are explained in sections 10 and 30.

[0038] In Fig. 6. After the start of the procedure at step S1, the eye diagram for the transmitted signal is created.

[0039] In the subsequent step S2, it is determined whether the reception quality of the transmit / receive device 13 is sufficient or not. If the answer in step S2 is YES, the procedure is completed. If the answer in step S2 is NO, the process continues to step S3.

[0040] In step S3, the detection time T is determined. D in Fig. 5 of the receiver modification device 12 is modified so that it is positioned as far to the right as possible in the hatched area of ​​the eye diagram of Fig. 5 is located. In the case of the Fig. In the case shown in section 5, the detection time T would be modified in this way. D1 The value lies slightly below 0.6 on the horizontal axis. The flow then continues to step S4.

[0041] In step S4, the receiver modification device 12 modifies the decision threshold E. Fig. 5, by the receiver modification device 12 slightly raising the decision threshold E to the modified decision threshold E1 in Fig. 5. In the case of the Fig. In the case shown in Figure 5, the modified decision threshold E1 is approximately 0.7 on the vertical axis. The procedure then returns to step S2.

[0042] In other words, the receiver modification device 12 shifts the detection time T D to the right to the modified detection time T D1 and slightly raises the decision threshold E to the modified decision threshold E1. Alternatively, step S3 can also be carried out after or together with step S4. Alternatively, only step S3 or only step S4 can be carried out.

[0043] The receiver modification device 12 therefore prevents higher error probabilities in the receive path 132 resulting from these different timings, which are caused by the slower transition from dominant to recessive bus level. Consequently, the quality of the signal received by the transmit / receive device 13 of the two receiving stations 10 and 30, which is based on one of the messages 45, 46, or 47, can be improved, thereby increasing the error robustness of the receiving stations 10 and 30.

[0044] Fig. Figure 7 shows a bus system 2 according to a second embodiment. In addition to at least one participant station 10, which is configured as in the first embodiment, the bus system 2 comprises at least one participant station 50 and at least one participant station 60. The participant stations 10, 50, and 60 are each connected to the bus line 40, as in the first embodiment. Messages 45, 46, and 47 can be transmitted between the individual participant stations 10, 50, and 60 in the form of signals via the bus line 40, as in the first embodiment. The participant stations 50 and 60 can also be, for example, control units or display devices of a motor vehicle, etc.

[0045] Subscriber stations 50 and 60 each have a transmitter modification unit 14 in addition to the communication unit 11 and the transmit / receive unit 13. Subscriber stations 10 and 60 also each have a receiver modification unit 12, whereas subscriber station 50 does not have a receiver modification unit 12. The receiver modification unit 12 is constructed in the same way as described in the first embodiment.

[0046] Fig. Figure 8 shows the structure of a transmit / receive device 13 of the subscriber station 50 in more detail as an example. The transmit / receive device 13 again has a transmit path 131 and a receive path 132, the receive path 132 being constructed as in the first embodiment. In contrast, the transmit path 131 in this embodiment has a first transistor 141, which is driven by a control signal S. H+is controlled by a second transistor 142, which is controlled by a control signal S H- is controlled by a third transistor 143, which is controlled by a control signal S L+ is controlled by a fourth transistor 144, which is controlled by a control signal S L-The first transistor 141 is connected to terminal A via a resistor 145. The second transistor 142 is connected to terminal B via a resistor 146. The third transistor 143 is connected to terminal A via a resistor 147. The fourth transistor 144 is connected to terminal B via a resistor 148. Additionally, the first and second transistors 141 and 142 are connected to terminal C_H for the first bus wire 41 of bus line 40. The third and fourth transistors 143 and 144 are connected to terminal C_L for the second bus wire 42 of bus line 40. A logic module 149 connects the transmit path 131 to other components of the transmit / receive device 13, which are not described in detail here.

[0047] In the transmitter / receiver unit 13, the transistors 141 to 144 and the resistors 145 to 148 form a transmitter output stage 150, which in Fig. 9 is still shown separately. Fig. Terminal 9 is labelled A with the voltage VDD and terminal B with ground GND. The transmitter output stage 150 is used to modify a signal to be transmitted, as is the case, for example, in Fig. 4 is shown in relation to the first embodiment.

[0048] For this purpose, the transmitter output stage 150 is configured to pre-distort the signal to be transmitted, which can also be called the transmit signal, in order to achieve a faster settling of the desired bus level on the bus line 40. The pre-distortion can be achieved by modifying the voltage level of the respective control signals S H+ , S H- , S L+ , S L- The voltage level is determined by the time following a state change of the respective control signal S. H+ , S H- , S L+ , S L- adjusted.

[0049] Here, transistors 141 to 144 are used. Fig. 8 and Fig. 9 is not operated in hard saturation, but driven linearly, so that a level with a defined internal resistance can be set for both connections C_L and C_H, and thus for the bus wires 41 and 42 of the bus line 40. The control signals S H+ and S H- These settings apply to connection C_H and thus to bus wire 41. The control signals S are set symmetrically to this. L+ and S L- for connection C_L and thus bus wire 42. To compensate for dynamic effects such as reloading processes, certain control functions, or time profiles, are applied to the control signals S within each bit state, in other words, within the range of a symbol duration. H+ , S H- , S L+ , S L- Used for pre-distortion of the signal to be sent and the impedance of the transmitting output stage 150.

[0050] This allows, as an application example, the desired levels to be reached as quickly as possible, which is particularly advantageous for the transition from dominant to recessive states in the data part of CAN-FD.

[0051] Fig. Figure 10 shows a corresponding procedure for improving the fault robustness of a participant station 50, 60. In this procedure, after the start of the procedure at step S10, the signal to be sent by the transmit path 131 is determined.

[0052] In a subsequent step S11, the signal to be sent is pre-distorted by means of the transmitter output stage 150 by adjusting the voltage levels of the respective control signals S H+ , S H- , S L+ , S L- It will be modified. After that, the process is complete.

[0053] Fig. Figure 11 shows an example of a control signal X1, which is used for the in Fig. The control signal X2 shown in 12 was pre-distorted. The control signal X2 in Fig. Figure 12 shows the form of the voltage level overshoot at each voltage level change of the signal, but this is only a specific example. In particular, the amplitude of the overshoots can also be the same in each case. Alternatively or additionally, the time course of at least one or all overshoots can also have the form of a sinusoidal arc, in particular an arc that is uniform across all overshoots. The resulting output signals Y1, Y2 of the transmitter output stage 150 are shown in Fig. 13 shown. Here it says in Fig. 13 the signal drawn with a dashed line for the output signal Y1, which is due to the control signal from Fig. 11 results. That in Fig. Signal 13, drawn with a solid line, represents the output signal Y2, which is determined by the control signal from Fig. 12. This implies that with the output signal Y2, which results from pre-distortion with the transmitter output stage 150, the levels are set earlier than with the undistorted signal.

[0054] Alternatively or additionally, the pre-distortion in step S11 can be achieved by modifying the output resistance of the transmit / receive device 13. The output resistance is also adjusted depending on the time after a state change.

[0055] The method according to the present embodiment with its two alternatives is particularly suitable for the transition from dominant to recessive states. This applies to both a CAN bus system and FlexRay. Furthermore, the method is especially suitable for addressing the problems associated with higher switching speeds in the data section of CAN-FD.

[0056] The present embodiment is simpler for achieving the best possible fault robustness than the first embodiment, since the transmission path 131 has a more significant influence on the problem to be solved.

[0057] According to a third embodiment, a pre-distortion is implemented according to the second embodiment. Therefore, the bus system according to the third embodiment is largely structured in the same way as the bus system according to the second embodiment.

[0058] In the present embodiment, however, depending on the section of a message 45, 46, 47, which is also called CAN frame, the transmitter characteristics of the transmit / receive device 13 are adapted in order to improve the switching edges.

[0059] Fig.Figure 14 shows message 45 as an example of a CAN frame. Message 45 has a message header 451, a data section 452, and a message end 453. In a CAN bus system, the message header 451 and the message end 453 are used for arbitration. The data section 452 contains the data intended for the operation of the respective terminal station 10, 20, 50, 60.

[0060] In the present embodiment, during step S11, the transmitter properties of the transmitter / receiver device 13 are adjusted only with respect to data section 452. However, the transmitter properties of the transmitter / receiver device 13 remain unchanged with respect to message header 451 and message end 453.

[0061] This preserves the possibility of arbitration at the message header 451 and the message end 453, and improves the signal quality on the bus line, especially in the data section at higher clock speeds. At the same time, the possibility of transmitting error bursts can be maintained through appropriate design.

[0062] According to a fourth embodiment, a pre-distortion is also implemented as in the second embodiment. Therefore, the bus system according to the fourth embodiment is largely structured in the same way as the bus system according to the second embodiment.

[0063] In the present embodiment, however, the pre-distortion of the control signals S H+ , S H- , S L+ , S L- In addition to pre-distortion of the transmitted signal, it is also used for dynamic adjustment of the impedance of the transmitter output stage 150.

[0064] All previously described configurations of the bus system 1, 2 of the participant stations 10, 20, 30, 50, 60 and of the method according to the first to fourth embodiments can be used individually or in all possible combinations. In addition, the following modifications are particularly conceivable.

[0065] The bus system 1, 2 described above, according to the first to fourth embodiments, is based on a CAN protocol-based bus system. However, the bus system 1, 2 according to the first to fourth embodiments can also be a different type of communication network. It is advantageous, but not a necessary requirement, that the bus system 1, 2 ensures, at least for certain periods of time, exclusive, collision-free access for a participant station 10, 20, 30, 50, 60 to the bus line 40 or a common channel of the bus line 40.

[0066] The bus system 1, 2 according to the first to fourth embodiment is in particular a CAN network or a CAN FD network or a LIN network or a FlexRay network.

[0067] The number and arrangement of the participant stations 10, 20, 30, 50, 60 in the bus systems 1, 2 according to the first to fourth embodiments is arbitrary. In particular, there can also be only participant stations 10 or only participant stations 50 or only participant stations 60 in the bus systems 1, 2 of the first to fourth embodiments.

[0068] The method can be optimized separately for each specific application, such as CAN-FD, FlexRay, etc. For multiple application areas, the application can also be automatically detected and adapted accordingly. For example, according to the first embodiment, the method is faster for CAN-FD than for CAN, so that no delay occurs that exceeds the tolerance of the respective protocol.

[0069] Participant stations 10, 30, 50, 60 offer a particular possibility for CAN-FD to increase the reception quality of CAN-FD to the range of usual CAN transmissions while using a significantly higher data rate.

[0070] The functionality of the previously described embodiments can be implemented, with regard to the first to fourth embodiments, in a transceiver or a transmit / receive device 13, and with regard to the first embodiment also in a communication control device 61, etc. Additionally or alternatively, it can be integrated into existing products.

Claims

[1] Participant station (10; 30; 50; 60) for a bus system (1; 2), with a transmitting / receiving device (13) for transmitting a signal via the bus system (1; 2) to another subscriber station and for receiving a signal via the bus system (1; 2), in which at least temporarily exclusive, collision-free access of a subscriber station (10, 20, 30, 50, 60) to a bus line (40) of the bus system (1; 2) is ensured, and a modification device (12; 14) for modifying the transmission characteristics of a transmit path (131) of the transmit / receive device (13) and / or the receiving characteristics of a receive path (132) of the transmit / receive device (13), wherein the modification device (14) comprises a transmitter output stage (150) for pre-distortion of the signal to be transmitted by the transmit / receive device (13) in order to prevent the bus level from settling on a transmit channel within one clock cycle (T S) of the signal to be sent, and / or wherein the modification device (12) is a receiver modification device for changing the detection time (TD) to the right in the eye diagram and the decision threshold (E) upwards in the eye diagram, wherein the transmitter output stage (150) for pre-distortion of the signal to be transmitted by the transmit / receive device (13) is designed such that it adapts the transmitter characteristics of the subscriber station (50; 60) depending on the section of a frame of the bus system (2). [2] Subscriber station (50; 60) according to claim 1, wherein the transmitter output stage (150) is configured to pre-distort the data section (452) of the signal to be transmitted by the transmit / receive device (13). [3] Subscriber station (50; 60) according to one of claims 1 to 2, wherein the transmitter output stage (150) is designed for pre-distortion of the signal to be transmitted by the transmit / receive device (13) such that it modifies the voltage level of the signal to be transmitted or the output resistance of the transmit / receive device (13). [4] Subscriber station (50; 60) according to claim 3, wherein the transmitter output stage (150) is configured such that it adjusts both the voltage level and the output resistance depending on the time after a change of state of the transmitted signal, and wherein the change of state of the transmitted signal is in particular a change from a dominant to a recessive state of the transmitted signal. [5] Subscriber station (50; 60) according to one of the preceding claims, wherein the transmitter output stage (150) has a first transistor (141) which is driven by a first control signal (S H+ ) is controllable, a second transistor (142) which is driven by a second control signal (S H- ) is controllable, a third transistor (143) which is driven by a third control signal (S L+ ) is controllable, and a fourth transistor (144) which is driven by a fourth control signal (S L- ) is controllable, wherein the first and second transistors (141, 142) are connected to a terminal (C_H) for a first bus wire (41), and wherein the third and fourth transistors (143, 144) are connected to a terminal (C_L) for a second bus wire (42). [6] Participant station (50; 60) according to claim 5, wherein the transmitter output stage (150) is designed such that it linearly drives the first to fourth transistors (141 to 144) in order to set a level with a defined internal resistance for the first and second bus conductors (41, 42), and / or wherein the transmitter output stage (150) is designed such that it provides predetermined time profiles for the first to fourth control signals (S) within each bit state H+ , S H- , S L+ , S L- ,.) is used for pre-distortion of the signal to be transmitted and impedance of a transmit path (131) of the transmit / receive device (13). [7] Bus system (1; 2), with a bus line (40), and at least two participant stations (10; 20; 30; 50; 60) which are connected to each other via the bus line (4) in such a way that they can communicate with each other, wherein at least one of the at least two participant stations (10; 20; 30; 50; 60) is a participant station (10; 30; 50; 60) according to one of the preceding claims [8] Method for improving the fault robustness of a participant station (10; 30; 50; 60) of a bus system (1; 2) according to claim 1, comprising the steps Sending, with a transmitting / receiving device (13) of the subscriber station (10; 30; 50; 60), a signal via the bus system (1; 2) to another subscriber station, or receiving, with the transmitting / receiving device (13) of the subscriber station (10; 30; 50; 60), a signal via the bus system (1; 2), in which at least temporarily exclusive, collision-free access of a subscriber station (10, 20, 30, 50, 60) to a bus line of the bus system is ensured, and Modify, with a modification device (12; 14) of the subscriber station, the transmit characteristics of a transmit path (131) of the transmit / receive device (13) and / or the receive characteristics of a receive path (132) of the transmit / receive device (13).

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