Subscriber station for a serial bus system and method for communicating in a serial bus system

Abstract

A subscriber station (10; 20; 30) for a serial bus system (1) and a method for communicating in a serial bus system (1) are provided. The subscriber station (10; 20; 30) has a communication control device (11; 21; 31) for controlling the communication of the subscriber station (10; 20; 30) with at least one other subscriber station (10; 20; 30) of the bus system (1) and for generating a transmission signal (TxD; TxD1; TxD2; TxD3; TxD4) in accordance with a frame (450), a transmission / reception device (12; 22; 32) which is designed to serially transmit the transmission signal (TxD; TxD1; TxD2; TxD3; TxD4) generated by the communication control device (11; 21; 31) to a bus (40) of the bus system (1) and which is designed to serially receive signals from the bus (40), and a marking module (15; 35) for evaluating whether a frame (450) received by the bus (40) should occur on the bus (40) and for marking the frame (450) with a marker (48; 480) in such a way that the transmission / reception device (12; 22; 32) transmits the marker (48; 480) to the bus (40) in order to inform at least one other subscriber station (10; 20; 30) of the bus system (1) of the result of the evaluation.

Description

TECHNICAL FIELD

[0001] The invention relates to a subscriber station for a serial bus system and a method for communication in a serial bus system, which work with a high data transmission rate and a high degree of flexibility and high fault tolerance, wherein unauthorized operation during operation of the superordinate technical device is prevented. BACKGROUND

[0002] Bus systems for communication between sensors and controllers, for example in vehicles, should enable the transmission of large data quantities depending on the number of functions of the technical device or the vehicle. Here, it is often required that data is transmitted from the sender to the receiver more quickly than before and large data packets can also be transmitted when required.

[0003] In vehicles, bus systems are currently in the introduction phase in which data is transmitted as messages in the standard ISO 11898-1 :2015 as CAN protocol specification with CAN FD. The messages are transmitted between bus users of the bus system, such as sensors, controllers, transmitters, etc. CAN FD is used in vehicles by most manufacturers in the first step with a data bit rate of 2 Mbit / s and an arbitration bit rate of 500 kbit / s.

[0004] In order to achieve an even greater data transmission rate, a successor bus system for CAN FD is currently being developed, which is referred to as CAN XL. CAN XL should support, in addition to pure data transmission over the CAN bus, other functions, such as safety, security and quality of service (QoS = Quality of Service). This is a basic property that is required, for example, in vehicles for automated driving.

[0005] It is extremely advantageous that CAN XL and CAN FD as well as Classical CAN are compatible, wherein CAN XL has at least the same fault tolerance as CAN FD and Classical CAN. In order to be compatible, CAN FD and CAN XL frames are distinguished in the CAN FD frame by means of a res bit after the end of arbitration.

[0006] However, it is problematic that CAN FD and Classical CAN do not provide security for the operation on layer 2 of the OSI layer model in the current design. The OSI layer model (OSI = Open Systems Interconnection Model) is a reference model for network protocols based on a layer architecture. In layer 2, network access is regulated in terms of frames. Since there is a lack of security on layer 2 in CAN FD and Classical CAN, manipulated frames can be brought into the bus system, which change the normal operation of the devices without authorization. This can lead to undesirable results and, if necessary, to a security risk for the superordinate technical device. SUMMARY

[0007] It is therefore the task of the present application to provide a user station for a serial bus system and a method for communicating in a serial bus system, which solve the problems mentioned previously. In particular, a user station for a serial bus system and a method for communicating in a serial bus system should be provided, which provide security for the operation on layer 2 of the OSI layer model, so that in addition to a high fault tolerance of the communication, a secure operation of the bus system is also achieved even at high data transmission rates and when the amount of valid data per frame rises.

[0008] The task is solved by a user station for a serial bus system. The user station has a communication control device for controlling the communication of the user station with at least one other user station of the bus system and for generating a transmission signal in one frame, a transmission / reception device, which is designed to transmit the transmission signal generated by the communication control device serially to a bus of the bus system and to receive signals serially from the bus of the bus system, and a marking module for evaluating whether a frame received by the bus should have occurred on the bus and for marking the frame in such a way with a mark that the transmission / reception device transmits the mark to the bus in order to inform at least one other user station of the bus system of the result of the evaluation.

[0009] The user stations (nodes) mentioned can mark frames received by the bus as "strange" without destruction due to their design. The marking is designed in such a way that all other user stations (nodes) receive the marking from the bus. The user stations mentioned can thus indicate to the other user stations that the frame just transmitted by the bus and correspondingly marked was not supposed to be transmitted.

[0010] As a result, a user station attacked by a virus cannot send frames that would normally be sent by other nodes without being detected. The security in the bus system can thus be improved.

[0011] Furthermore, the user station can be designed to use the marker for other things. The marker can be used, in particular, for at least one of the following information: information about the temporal and / or functional application of the frame, information about the reception of the frame from the bus, etc.

[0012] The use of the marker thus enables the user station to ensure the transmission and reception of frames with a high functional safety, a high flexibility with regard to current events in the operation of the bus system and with a small error rate even when the amount of valid data per frame rises.

[0013] Here, the user station in the bus system is able to maintain the arbitration known from CAN in the first communication phase and also to increase the transmission rate again significantly compared to CAN or CAN FD.

[0014] The method performed by the user station can also be used when there is at least one CAN user station and / or at least one CAN FD user station in the bus system which transmits messages according to the CAN protocol and / or the CAN FD protocol.

[0015] Advantageous further embodiments of the user station are explained below.

[0016] The marker module can optionally be designed to mark frames which should not occur on the bus.

[0017] The marker module can optionally be designed to evaluate, by comparison with a list, whether a frame received by the bus has to be marked on the bus.

[0018] According to one embodiment, the marker module is designed to insert the marker into the frame without destroying the frame.

[0019] It is conceivable that the marker module is designed to insert the marker into the frame after a data field in which the valid data of the frame are inserted.

[0020] It is possible that the marker module is designed to insert the marker as a bit inversion at a position set for the user station of the bus system, indicating that the frame was not received correctly, wherein the marker module is designed to insert a marker into the frame which shows a time length for which the frame was not received correctly.

[0021] In a special variant, the marker module is designed to insert the marker into the frame as a marker having a time length of N bits, wherein N is a natural number greater than or equal to 1. Here, the marker module can be designed to select the length of the marker depending on what the marker means.

[0022] According to an embodiment, the marking module is designed to insert the marker after the frame without destroying the frame. Here, the marking module can be designed to insert the marker after the frame starting from the second bit of the intermediate frame spacing. The marker alternatively or additionally has a greater length than the maximum length of the overload flag that can be transmitted in the intermediate frame spacing.

[0023] It is possible for the transmitting / receiving device for serially transmitting the transmission signal generated by the communication control device to the bus of the bus system to be designed in such a way that for the frame the bit time of the signal transmitted onto the bus in the first communication phase can be different from the bit time of the signal transmitted in the second communication phase.

[0024] It is possible for the frame to be constructed in a CAN FD-compatible manner, wherein in the first communication phase it is agreed which user station of the bus system obtains at least temporarily exclusive, collision-free access to the bus in the following second communication phase.

[0025] The user station described previously can be part of a bus system, the bus system further comprising a bus and at least two user stations, the user stations being connected to one another via the bus in such a way that the user stations can communicate with one another serially. Here, at least one of the at least two user stations is the user station described previously.

[0026] The task described previously is also solved by a method for communicating in a serial bus system. The method is implemented by a user station of the bus system, the user station having a communication control device, a transmitting / receiving device and a marking module, wherein the method has the steps of controlling the communication of one user station of the bus system with at least one other user station with the communication control device, wherein the communication control device is designed to generate a transmission signal in frames, receiving the signal serially from a bus of the bus system with the transmitting / receiving device, evaluating with the marking module whether a frame received by the bus should occur on the bus, and marking a frame with a marker with the marking module in such a way that the transmitting / receiving device transmits the marker to the bus in order to inform at least one other user station of the bus system of the result of the evaluation.

[0027] The method offers the same advantages as those mentioned previously with reference to the user station.

[0028] Further possible refinements of the application also include combinations of features or embodiments which have not been explicitly mentioned previously or which are described subsequently with reference to the embodiments. Here, the person skilled in the art can also add individual aspects as improvements or supplements to the respective basic form of the application. BRIEF DESCRIPTION OF DRAWINGS

[0029] The application is explained in more detail below with reference to the drawings and by means of embodiments.

[0030] Figure 1 is a simplified block diagram of a bus system according to the first embodiment;

[0031] Figure 2 is a diagram for illustrating the structure of a message which can be transmitted by a subscriber station of a bus system according to the first embodiment;

[0032] Figure 3 is a simplified schematic block diagram of a subscriber station of a bus system according to the first embodiment;

[0033] Figure 4 is a time curve of the bus signals CAN-XL_H and CAN-XL_L in a subscriber station according to the first embodiment;

[0034] Figure 5 is a time curve of the voltage difference VDIFF of the bus signals CAN-XL_H and CAN-XL_L in a subscriber station according to the first embodiment;

[0035] Figures 6 to 9 one example of transmit signals TxD1 to TxD4 which are generated during a transmit frame in four different subscriber stations of a bus system according to the first embodiment is shown; and

[0036] Figure 10 a time curve of the signal TxD4 at the TXD terminal of a fourth subscriber station of a bus system according to the second embodiment is shown, which fourth subscriber station is currently acting as RX subscriber station and receives frames of signals according to the Figure 6 at the bus of the bus system.

[0037] In the drawings, identical or functionally identical elements are provided with the same reference signs if not stated otherwise. DETAILED DESCRIPTION

[0038] Figure 1 A bus system 1 is shown by way of example which is designed, inter alia, essentially for a CAN bus system, a CAN FD bus system, a CAN XL bus system and / or modifications thereof, as will be explained in the following. The bus system 1 can be used in vehicles, in particular motor vehicles, aircraft, etc., or in hospitals, etc.

[0039] In Figure 1In the case shown, the bus system 1 has a plurality of subscriber stations 10, 20, 30, which are connected to a bus 40 with a first bus conductor 41 and a second bus conductor 42. The bus conductors 41, 42 can also be referred to as CAN H and CAN L or CAN-XL H and CAN-XL L and are used for electrical signal transmission after a coupling high level or a recessive level or other levels for signals in the transmitting state. By means of the bus 40, messages 45, 46 can be transmitted in the form of signals between the individual subscriber stations 10, 20, 30 serially. If, as shown by the jagged black solid arrow in Figure 1 , an error occurs on the bus 40 at the time of communication, an error frame 47 (Error Flag) can optionally be transmitted. The subscriber stations 10, 20, 30 are, for example, controllers, sensors, display devices, etc. of a motor vehicle.

[0040] As shown in Figure 1 , the subscriber station 10 has a communication control device 11, a transmitting / receiving device 12 and a marking module 35. The transmitting / receiving devices 12, 22, 32 of the subscriber stations 10, 20, 30 are each connected directly to the bus 40, even if this is not shown in Figure 1 .

[0041] The communication control devices 11, 21, 31 are each used to control the communication of the respective subscriber station 10, 20, 30 via the bus 40 with at least one other subscriber station of the subscriber stations 10, 20, 30 connected to the bus 40.

[0042] The communication control device 11, 31 creates and reads first messages 45, which are, for example, modified CAN messages 45. Here, the modified CAN messages 45 are built on the basis of the CAN XL format, which is explained in more detail with reference to Figure 2 . Furthermore, the communication control device 11, 31 can be designed to provide or receive CAN XL messages 45 or CAN FD messages 46 to or from the transmitting / receiving device 32, as required. The communication control device 11, 31 thus creates and reads first messages 45 or second messages 46, wherein the first and second messages 45, 46 are distinguished by their data transmission standard, i.e. in this case CAN XL or CAN FD.

[0043] The communication control device 21 can be designed like a conventional CAN controller according to ISO 11898-1 :2015, that is to say, like a CAN FD fault-tolerant conventional CAN controller or a CAN FD controller. The communication control device 21 creates and reads second messages 46, for example CAN FD messages 46. In the CAN FD messages 46, a number of 0 to 64 data bytes can be included, which are also transmitted at a significantly faster data transmission rate than in conventional CAN messages. The communication control device 21 is designed, in particular, like a conventional CAN FD controller.

[0044] The transmitting / receiving device 22 can be designed like a conventional CAN transceiver or a CAN FD transceiver according to ISO 11898-1 :2015. The transmitting / receiving devices 12, 32 can be designed to provide or receive messages 45 in the CAN XL format or messages 46 in the current CAN FD format to or from the associated communication device 11, 31, as required.

[0045] With the two subscriber stations 10, 30, messages 45 in the CAN XL format can be formed and then transmitted and received.

[0046] Figure 2 A CAN XL frame 450 is shown for a message 45, which is provided by the communication control device 11 to the transmitting / receiving device 12 for transmission onto the bus 40. Here, the communication control device 11 creates a frame 450 in the current embodiment, which is compatible with CAN FD, as is also shown in Figure 2 The same explanations apply analogously to the communication control device 31 and / or the transmitting / receiving device 32 of the subscriber station 30.

[0047] According to Figure 2 , the CAN XL frame 450 for CAN communication on the bus 40 is divided into different communication phases 451, 452, namely an arbitration phase 451 and a data phase 452. The frame 450 has an arbitration field 453, a control field 454, a data field 455, a checksum field 456 for the checksum FCRC and the transition sequence ADS, and an acknowledgement field 457.

[0048] In the arbitration phase 451, it is agreed bit by bit between the subscriber stations 10, 20, 30 with the aid of an identifier (ID) in the arbitration field 453 which subscriber station 10, 20, 30 wants to transmit the message 45, 46 with the highest priority and thus obtains exclusive access to the bus 40 of the bus system 1 for the next period of time for transmission in the immediately following data phase 452. In the arbitration phase 451, a physical layer is used as in CAN and CAN-FD. The physical layer corresponds to the bit transmission layer or layer 1 of the well-known OSI model (Open Systems Interconnection model).

[0049] An important point during the phase 451 is that a known CSMA / CR method is used, which allows the subscriber stations 10, 20, 30 to access the bus 40 simultaneously without violating higher priority messages 45, 46. Thereby it is possible to add further bus subscriber stations 10, 20, 30 to the bus system 1 relatively simply, which is extremely advantageous.

[0050] The CSMA / CR method results in a so-called recessive state necessarily being given on the bus 40, which can be overwritten by other subscriber stations 10, 20, 30 with a dominant state on the bus 40. In the recessive state, a high resistance is present at the respective subscriber stations 10, 20, 30, which in combination with the parasitics of the bus wiring leads to a long time constant. This results in the maximum bit rate of the current CAN-FD physical layer being limited to currently about 2 Mbit / s in real vehicle use.

[0051] In the data phase 452, in addition to a part of the control field 454, the valid data of the CAN-XL frame or message 45 from the data field 455 and the checksum field 456 for the checksum FCRC are also transmitted and in addition the field DAS, which serves to switch the data phase 452 back to the arbitration phase 451.

[0052] The transmitter of the message 45 only begins to transmit the bits of the data phase 452 to the bus 40 when the subscriber station 10 has obtained arbitration as a transmitter and the subscriber station 10 therefore has exclusive access to the bus 40 of the bus system 1 for transmission.

[0053] More broadly, in a bus system with CAN XL, the following different properties can be implemented compared to CAN or CAN FD:

[0054] a) the proven properties are adopted and, if necessary, adapted, which are responsible for the robustness and user-friendliness of CAN and CAN FD,

[0055] in particular the frame structure with identifier and arbitration according to the CSMA / CR method,

[0056] b) increase the net data rate, in particular to about 10 Mbit / s,

[0057] c) increase the size of the valid data per frame, in particular to about 2 kBytes or any other value.

[0058] As Figure 2 indicated, the user station 10 uses in the arbitration phase 451 as first communication phase, partially, in particular up to the FDF bit (inclusive), the format known from CAN / CAN-FD according to ISO 11898-1 :2015. Conversely, the user station 10 uses from the FDF bit onwards in the first communication phase as well as in the second communication phase, the data phase 452, the CAN XL format explained next.

[0059] In the current embodiment, CAN XL and CAN FD are compatible. Here, the res bit known from CAN FD, also called XLF bit next, is used for the conversion from the CAN FD format to the CAN XL format. The frame format up to the res bit is thus identical from CAN FD and CAN XL. The receiver only recognizes in the res bit in which format the frame was sent. The CAN XL user station, here the user stations 10, 30, also supports CAN FD.

[0060] As Figure 2 indicated, an alternative to the frame 450 in which an 11-bit Identifier is used, a CAN extended frame format is alternatively possible, in which a 29-bit Identifier is used. This up to the FDF bit is identical to the known CAN FD extended frame format from ISO 11898-1 :2015.

[0061] According to Figure 2 , the frame 450 is identical from the SOF bit up to and including the FDF bit to the CAN FD basic frame format according to ISO 11898-1 :2015. The known structure is thus not further explained here. The bits with a fixed value, i.e. 0 or 1, are marked with a black line. The bits shown in Figure 2 with a thick line below the line are sent in the frame 450 as explicit or 0'. The bits shown in Figure 2 with a thick line above the line are sent in the frame 450 as implicit or 1'. In the CAN XL data phase 452, symmetric 1' and 0' levels are used instead of the implicit and linear levels.

[0062] Two different padding rules are typically used when generating the frame 450. Until the XLF bit position in the control field 454, the dynamic bit padding rule of CAN FD applies, thus one inverse padding bit is inserted after 5 identical bits in sequence. This padding bit is also called dynamic padding bit. The fixed padding rule applies after the resXL bit in the control field 454, thus a fixed padding bit can be inserted after a fixed number of bits. Alternatively, instead of only one padding bit, a number of 2 or more bits can be inserted as fixed padding bits.

[0063] In the frame 450, directly after the FDF bit is the XLF bit, which corresponds to the "res bit" in the CAN FD basic frame format from this position, as mentioned before. If the XLF bit is transmitted as 1, i.e. implicitly, it identifies the frame 450 as a CAN XL frame. For a CAN FD frame, the communication control device 11 sets the XLF bit to 0, i.e. explicitly.

[0064] In the frame 450, directly after the XLF bit is the resXL bit, which is an explicit bit for future use. The resXL has to be transmitted as 0, i.e. explicitly, for the frame 450. But if a user station 10 receives the resXL bit as 1, i.e. implicitly, the receiving user station 10 enters a protocol exception state, for example, as designed for res = 1 in the message 46 in CAN FD. The resXL bit can alternatively be defined just the other way around, i.e. it has to be transmitted as 1, i.e. implicitly. In this case, the receiving user station enters the protocol exception state at an explicit resXL bit.

[0065] In the frame 450, the sequence ADS (Arbitration Data Switch) follows immediately after the resXL bit, in which a predetermined bit sequence is encoded. This bit sequence allows a simple and secure transition from the bit rate of the arbitration phase 451 (arbitration bit rate) to the bit rate of the data phase 452 (data bit rate). The bit sequence of the ADS sequence is also composed, for example, of the ALl bit, which is transmitted explicitly, i.e. as 0. The ALl bit is the last bit of the arbitration phase 451. In other words, the ALl bit is the last bit before the transition into the data phase 452 with short bits. In the ALl bit, the transition of the physical layer takes place in the transmitting / receiving device 12, 22, 32. The ALl bit can alternatively have the value 1, depending on which value (0 or 1) better suits the transition of the physical layer in the transmitting / receiving device 12, 32 (transceiver). The two subsequent bits DHl and DLl are already transmitted at the data bit rate. The bits DHl and DLl are therefore very short bits in time of the data phase 452 in the CAN XL. If the ALl bit has the value 1, then the DLl bit and then the DHl bit follow immediately after it.

[0066] In the frame 450, the sequence ADS is followed by the PT field, which denotes the content of the data field 455. The content indicates which type of information is contained in the data field 455. The PT field indicates, for example, whether an "Internet Protocol" (IP) frame, or a tunnelled Ethernet frame or other frame, is present in the data field 455.

[0067] The DLC field is connected to the PT field, in which a data length code (DLC = Data Length Code) is inserted, which indicates the number of bytes in the data field 455 of the frame 450. The data length code (DLC) can assume any value from 0 to the maximum length of the data field 455 or data field length. If the maximum data field length is, in particular, 2048 bits, then the data length code (DLC) requires 11 bits, assuming that DLC = 0 means a data field length with 1 byte number and DLC = 2047 means a data field length with 2048 byte number. Alternatively, a data field 455 with a length of 0 can be permitted, as in the CAN. Here, DLC = 0 encodes, for example, a data field length of 0 byte number. The maximum encodable data field length is, for example, 11 bits, i.e. (2 11 )-1 = 2047.

[0068] In Figure 2In the example of frame 450, following the DLC field is a header checksum HCRC. The header checksum HCRC is a checksum for protecting the header of frame 450, i.e. all relevant bits from the start of the SOF bit of frame 450 to the start of the header checksum HCRC, including all dynamic and optional fixed padding bits up to the start of the header checksum HCRC. The relevant bits only include the bits of the frame header which have a value that can change. In other words, the relevant bits do not include bits which always have a fixed value in frame 450. Such bits with a value that cannot change are thus not protected, since these bits have a fixed value. The length of the header checksum HCRC and thus of the checksum polynomial can be chosen according to the desired Hamming distance, as for a cyclic redundancy check (CRC). The data words to be protected by the header checksum HCRC are more than 27 bits in the data length code (DLC) of 11 bits. The polynomial of the header checksum HCRC must thus be at least 13 bits long in order to achieve a Hamming distance of 6.

[0069] In frame 450, following the header checksum HCRC is a data field 455. The data field 455 consists of 1 to n data bytes, where n is for example 2048 bytes or 4098 bytes or any other value. It is alternatively conceivable that the data field length is 0. The length of the data field 455 is encoded in the DLC field as explained before.

[0070] In frame 450, following the data field 455 is a frame checksum FCRC. The frame checksum FCRC consists of the bits of the frame checksum FCRC. The length of the frame checksum FCRC and thus of the CRC polynomial can be chosen according to the desired Hamming distance. The frame checksum FCRC protects the entire frame 450. Alternatively, it is possible that only the data field 455 is protected with the frame checksum FCRC.

[0071] In frame 450, following the frame checksum FCRC is a sequence DAS (Data Arbitration Switch), in which a predetermined bit sequence is encoded. This bit sequence allows a simple and secure transition from the data bit rate of the data phase 452 to the arbitration bit rate of the arbitration phase 451. As Figure 2As shown in the middle, the bit sequence starts, for example, with the data bits DH2, DH3 sent as 1 and the data bits DL2, DL3 sent as 0. This is the last 4 bits of the data phase 452. Thus the DL3 bit is the last short bit, that is, the last bit before the transition to the arbitration phase 451 with long bits. Following the bits is the AH1 bit with the value 1 of the arbitration phase 451. Within the AH1 bit the transition of the physical layer in the sending / receiving device 12, 32 (transceiver) takes place. The AH1 bit can alternatively have the value 0, depending on which value (0 or 1) better suits the transition of the physical layer in the sending / receiving device 12, 32 (transceiver). Only the receiver of the frame 450, that is, the RX subscriber station 10, 30 which does not send the received frame 450, uses the bit sequence DH2, DH3, DL2, DL3 not only for synchronization but also as a format check pattern. With this bit sequence the RX subscriber station 10, 30 can recognize whether it has misaligned the scanning of the bit stream received from the bus 30, for example, by 1 bit or 2 bits, etc. According to yet another example, the DAS field has three bits, namely the DH2 bit, the DL2 bit and the AH1 bit. Of these bits, the first and last bits are sent as 1 and the middle bit is sent as 0.

[0072] In the above example, in the receiving subscriber station the last synchronization is performed at the edge between the DH3 bit and the DL2 bit or the DH2 bit and the DL2 bit before the transition from the data phase 452 to the arbitration phase 451.

[0073] In the frame 450, following the sequence DAS is the acknowledgement field 457, which begins with the RP field. In the RP field a sync pattern is provided which allows the receiving subscriber station 10, 30 to recognize the beginning of the arbitration phase 451 after the data phase 452. The sync pattern allows the receiving subscriber station 10, 30 which does not know the correct length of the data field 455, for example, due to an erroneous header checksum HCRC, to synchronize. These subscriber stations then send a "negative acknowledgement" in order to signal the erroneous reception. This is particularly important when the CAN XL does not allow an error flag 47 in the data field 455.

[0074] In the acknowledgement field 457, following the RP field is a plurality of bits for acknowledging or not acknowledging the correct reception of the frame 450. In the example shown in Fig. 4, the acknowledgement field 457 has 4 bits, namely the RP bit, the AH2 bit, the ACK bit and the ACK2 bit. The RP bit is sent as 1 and the AH2 bit is sent as 0. The ACK bit is sent as 1 and the ACK2 bit is sent as 0. The ACK bit is sent as 1 and the ACK2 bit is sent as 0. Figure 2The example includes an ACK bit, an ACK-dlm bit, a NACK bit, and a NACK-dlm bit. When the receiving user stations 10 and 30 correctly receive frame 450, they send the ACK bit as dominant. The transmitting user stations send the ACK bit as recessive. Therefore, the bits initially sent to bus 40 in frame 450 can be overwritten by the receiving user stations 10 and 30. The ACK-dlm bit is sent as a recessive bit to separate it from other fields. The NACK bit and NACK-dlm bit are used to allow the receiving user stations to signal on bus 40 that frame 450 was not correctly received. The NACK-dlm bit functions the same as the ACK-dlm bit. The NACK bit is used to mark frame 450 as described below.

[0075] In frame 450, following the ACK field 457 is the End of Frame (EOF). The bit sequence of the EOF field is used to mark the end of frame 450. The EOF field is responsible for sending 8 recessive bits at the end of frame 450. This bit sequence cannot appear within frame 450. Therefore, the end of frame 450 can be safely identified by user stations 10, 20, and 30.

[0076] The End-of-Flight (EOF) field has a different length depending on whether a dominant or recessive bit is seen in the NACK bit sequence. When the transmitting user station has already received a dominant NACK bit, the EOF field has 7 recessive bits. Otherwise, the EOF field is only 5 dominant bits long.

[0077] In frame 450, following the End-of-Frame Field (EOF), there is the Intermission Field (INT-Intermission Field) of 458. Figure 9 It is not shown in the middle, but in Figure 10 and Figure 3 As shown in the diagram. This intermediate frame spacing of 458 (INT) is designed as in the CAN FD corresponding to ISO11898-1:2015.

[0078] Figure 3 The basic structure of user station 10 is shown, which includes a communication control device 11, a transmitting / receiving device 12, and a tag module 15, which is part of the communication control device 11. User station 30 is configured as follows... Figure 1 Constructed in a similar manner as shown, but the tag module 35 is based on Figure 3 It is arranged separately from the communication control device 31 and the transmitting / receiving device 32. Therefore, the user station 30 is not described separately.

[0079] according to Figure 3The subscriber station 10 has, in addition to the communication control device 11 and the transmitting / receiving device 12, a microcontroller 13, to which the communication control device 11 is assigned, and a system ASIC 16 (ASIC = Application Specific Integrated Circuit), which can alternatively be a system base chip (SBC), on which the functions required by the electronic components of a plurality of subscriber stations 10 are concentrated. In the system ASIC 16, in addition to the transmitting / receiving device 12, a power supply device 17 is installed, which supplies the transmitting / receiving device 12 with electrical power. The power supply device 17 usually provides a voltage of 5 V, CAN_Supply. But the power supply device 17 can provide other voltages of other values, as required. The power supply device 17 can additionally or alternatively be designed as a power supply.

[0080] The marking module 15 has an evaluation block 151 and an insertion block 152, which will be explained more precisely in the following.

[0081] In addition, the transmitting / receiving device 12 has a transmitting module 121 and a receiving module 122. Even if the receiving module 122 is always referred to in the following as part of the transmitting / receiving device 12, it can alternatively be arranged in a separate device outside the transmitting module 121. The transmitting module 121 and the receiving module 122 can be constructed as in a conventional transmitting / receiving device 12. The transmitting module 121 can in particular have at least one operational amplifier and / or transistor. The receiving module 122 can in particular have at least one operational amplifier and / or transistor.

[0082] The transmitting / receiving device is connected to the bus 40, more precisely to a first bus wire 41 of the bus for CAN_H or CAN-XL_H and to a second bus wire 42 of the bus for CAN_L or CAN-XL_L. The voltage supply of the power supply device 17 for supplying the first and second bus wires 41, 42 with electrical power, in particular with the voltage CAN-Supply, is accomplished by means of at least one connection 43. The connection to ground or CAN_GND is achieved by means of a connection 44. The first and second bus wires 41, 42 are terminated with a termination resistor 49.

[0083] The first and second bus wires 41, 42 are connected in the transmitting / receiving device 12 not only to the transmitting module 121, also called transmitter, but also to the receiving module 122, also called receiver, even if the connections are not shown in Figure 4 for simplicity.

[0084] In the operation of the bus system 1, the transmitting module 121 converts the transmit signal TXD or TxD of the communication control device 11 into the respective signals CAN-XL_H and CAN-XL_L for the bus wires 41, 42 and transmits these signals to the bus 40 at the connections for CAN_H and CAN_L.Figure 5 An example is shown for signals CAN-XL_H and CAN-XL_L. A signal difference VDIFF = CAN-XL_H - CAN-XL_L is formed on bus 40, which... Figure 3 As shown in the image.

[0085] Figure 4 The receiving module 122 is based on Figure 5 The signals CAN-XL_H and CAN-XL_L received by bus 40 or according to Figure 3 The signal difference VDIFF forms the received signal RXD or RxD. For example... Figure 4 As shown, the receiving module 122 transmits the received signal RXD or RxD to the communication control device 11.

[0086] Except in an idle or ready state (idle or hibernating), the transmitting / receiving device 12 with receiving module 122 always stops the transmission of data or messages 45, 46 on bus 40 during normal operation, more precisely, regardless of whether the transmitting / receiving module 12 is the transmitter of message 45.

[0087] according to Figure 5 For example, signals CAN-XL_H and CAN-XL_L have dominant and recessive bus levels 401 and 402, respectively, at least during arbitration phase 451, as is known from CAN. The individual bits of signal VDIFF with bit time t_bt can be identified by receiver module 122 with a receive threshold T_a of, for example, 0.7V during arbitration phase 451, as... Figure 4 As shown in the diagram. In data phase 452, the bit rates of signals CAN-XL_H and CAN-XL_L are transmitted faster than in arbitration phase 451, i.e., with a shorter bit time t_bt. Therefore, signals CAN-XL_H and CAN-XL_L differ from conventional signals CAN_H and CAN_L in data phase 452, at least in their faster bit rates. Furthermore, if signals CAN-XL_H and CAN-XL_L are generated using other physical layers in data phase 452, then the reception threshold in receiving module 122 will also be converted, for example, to the approximately 0.0V reception threshold of data phase 452.

[0088] Figure 5 The sequence of states 401 and 402 for signals CAN-XL_H and CAN-XL_L. Figure 3 The resulting voltage VDIFF variation curve is only used to illustrate the function of user station 10. The order of data states for bus states 401 and 402 can be selected as needed.

[0089] in other words, Figure 4 The sending module 121 according toFigure 3 In the first operating mode, a first data state is generated as bus state 402 with different bus levels for the two bus cores 41 and 42 of the bus line, and a second data state is generated as bus state 401 with the same level for the two bus cores 41 and 42 of the bus line of bus 40. Furthermore, Figure 3 The transmitting module 121 transmits bits at a higher bit rate to the bus 40 based on the time variation curves of signals CAN-XL_H and CAN-XL_L in the second operating mode, including the data phase 452. As mentioned, signals CAN-XL_H and CAN-XL_L can also be generated in the data phase 452 using a different physical layer than in CAN FD. The bit rate in the data phase 452 can thus be further increased compared to CAN FD.

[0090] Figures 6 to 9 The marking module 15, and in particular the evaluation block 151 of the marking module, is used to evaluate whether the currently received frame 450 should be marked. For this purpose, the evaluation block 151 has a receive filter 1511, which can filter out predetermined frames 450.

[0091] To this end, the receive filter 1511 has a filter standard 151B, which determines whether frame 450 has attributes that should not appear on bus 40. Filter standard 151B is created using features representing security risks of bus system 1. Filter standard 151B is stored as a list, and thus evaluation block 151 performs a comparison with the list. This list can be called a security feature blacklist. The list can in particular have identifier IDs, for which predetermined frames 450 with predetermined content are not allowed to be sent. For example, a sensor with a special identifier should not send frames 450 that are normally expected by the controller or other sensors, transmitters, or drivers. Any variations are conceivable and can be stored in the list or filter standard 151B. The blacklist of user station 10, for example, contains all identifier IDs that should be exclusively sent by user station 10. This means that when user station 10 receives a message or frame 450 from bus 40 and the receive filter 1511 with filter standard 151B finds an attribute (Treffer, hit) that should not appear on bus 40, then this involves a message or frame 450 that was sent without permission on bus 40.

[0092] Furthermore, the reception filter 151 1 has a filter criterion 151 W with which it can be determined whether the frame 450 is of interest to the subscriber station 10. The list thus corresponds to a so-called acceptance filter. The filter criterion 151 W is stored, inter alia, as a list. Such a list can be referred to as a white list.

[0093] The subscriber station 10 uses the reception filter 151 1, in particular in the case where the subscriber station 10 is not the transmitter of the frame 450 currently being transmitted on the bus 40, i.e. acts as an RX subscriber station.

[0094] If the subscriber station 10, as an RX subscriber station with the evaluation module 151, more precisely its reception filter 151 1, recognizes, using the filter criterion 151 B, that the frame 450 just transmitted on the bus 40 should not be there, the evaluation block 15 signals this to the insertion block 152. The evaluation block 15 instructs the insertion block 152, inter alia, to mark the frame 450 on the bus 40 with the marker 48. In other words, the RX subscriber station (receiving node) can instruct its communication control device 1 1, in particular the CAN XL protocol controller, to mark the frame 450 on the bus 40 with the marker 48 in the described case.

[0095] To this end, the communication control device 1 1, in particular the CAN XL protocol controller, transmits N explicit bits in the frame 450 in the NACK field. The explicit bits override the bit NACK. N is ideally 2, since the NACK bit is 1 bit long, if it is transmitted at all. The insertion block 152 can alternatively be designed to distinguish between a plurality of different markers 48, in particular a marker 48 with N = 2 bits, a marker 48 with N = 3 bits and optionally additionally a marker 48 with N = 4 bits. Other examples are of course conceivable. If the insertion block 152 can distinguish between different markers 48, the different markers 48 have different meanings. The different markers 48 override one another. The reason for this is that the number of bits of the marker 48 and thus the length of the marker 48 is different. If the NACK bit is not required in the bus system 1, a marker 48 with N = 1 bit length can alternatively occur.

[0096] After the received frame 450 has been marked with the insertion block 152, all other subscriber stations 20, 30 at the bus 40 see that at least one subscriber station considers this frame 450 to be "strange" on the bus 40, in other words not to conform to a predetermined pattern and, if necessary, to represent or can represent a safety risk. Each of the subscriber stations 10, 30 at the bus 40 can in particular process this marked frame 450.

[0097] One of the subscriber stations 10, 30, in particular its communication control device 11, 31 (protocol controller) can be designed, for example, in such a way that the marked frame 450 is discarded, although it is received without errors.

[0098] One of the subscriber stations 10, 30, in particular its communication control device 11, 31 (protocol controller) can alternatively be designed to switch into an emergency mode, since such an event, the frame 450 marked with the marker 48, should never occur. But if such an event, the frame 450 marked with the marker 48, occurs, then malicious software is most likely on one of the controllers of the subscriber stations 10, 30 at the bus 40. Such malicious software attempts to manipulate the behavior of the superordinate technical device, in particular of the vehicle, in such a way that the malicious software sends frames 450 that should have been sent only by the other subscriber stations 10, 20, 30 at the bus 40. Such an event, the marked frame 450, can alternatively occur when an error configuration of the controller occurs. In this case, this can lead to the same effect, the marked frame 450.

[0099] The marking 48 of the received frame 450 achieved with the insertion block 152 thus also contributes to detecting an error configuration.

[0100] Figure 6 An example of the transmission signal TxD is shown, which occurs at the connection TXD of the respective subscriber station 10, 10, 30, 30 during and after the transmission of the frame 450 in four different subscriber stations 10 of the bus system 1. This is to say, it is subsequently assumed that the bus system 1 has at least four identically constructed subscriber stations 10. Of course, at least one of the subscriber stations 10 can alternatively also be constructed as the subscriber station 30.

[0101] Figure 7 The time curve of the transmission signal TxD1 at the TXD connection of the first subscriber station 10 of the bus system 1 is shown, which first subscriber station transmits the frame 450 to the bus 40 at the moment and thus acts as TX subscriber station.

[0102] Figure 6 The time curve of the transmission signal TxD2 at the TXD connection of the second subscriber station 10 of the bus system 1 is shown, which second subscriber station acts as RX subscriber station at the moment and receives the frame 450 from the bus 40 according to Figure 8 .

[0103] Figure 6 The time curve of the transmission signal TxD3 at the TXD connection of the third subscriber station 10 of the bus system 1 is shown, which third subscriber station acts as RX subscriber station at the moment and receives the frame 450 from the bus 40 according to Figure 9The signal is received from bus 40, frame 450.

[0104] Figure 6 The time variation curve of signal TxD4 transmitted at the TXD connector of the fourth user station 10 in bus system 1 is shown. This fourth user station is currently operating as an RX user station and according to... Figure 6 The signal receives frames from the bus of the bus system.

[0105] Therefore, the first user station 10 uses the button Figure 7 The transmit signal TxD1 sends frame 450 to bus 40. Frame 450 is received by other user stations 10. In the arbitration phase 451, frame 450 is transmitted using bits with a first duration t_b1. In the data phase 452, frame 450 is transmitted using bits with a second duration t_b2. The second duration t_b2 is shorter than the first duration t_b1, as previously explained.

[0106] Second user station 10 correctly received frame 450 and confirmed this with an ACK, as shown in Figure 8 As shown in the transmitted signal TxD2.

[0107] Conversely, third user station 10 did not correctly receive frame 450. Therefore, the third user station acknowledged the reception of frame 450 with a NACK, as shown in... Figures 3 to 5 As shown in the transmit signal TxD3, NACK is inserted as an inverted bit into frame 450. In other words, NACK is inserted as the inverted value of the bit transmitted in the transmit signal TxD1.

[0108] Furthermore, the fourth user station 10 classifies frame 450 as a "strange" frame 450. Therefore, the fourth user station 10 uses its tagging module 15 to tag frame 450 with tag 48, as previously referenced. Figure 9 As explained. Therefore, user station 10 sends a transmit signal TxD4 with marker 48 in the bit NACK and NCK dlm, as... Figure 9 As shown in the diagram. Marker 48 is... Figure 8 The example has two dominant bits. Therefore, N = 2. Furthermore, marker 48 in NACK and NCK dlm is inserted as an inverted bit into frame 450. In other words, marker 48 is inserted as the inverted value of the NACK and NCK dlm bits transmitted in the transmit signal TxD1.

[0109] As a result of the marking 48 received in its reception signal RxD and thus seen by all subscriber stations 10, three RX subscriber stations 10, namely the second to fourth subscriber stations 10, react to the frame 450 according to one of the possibilities described previously. The respectively selected possibility of reacting to the marking 48, more precisely to the frame 450, can be fixedly set from the outset or set in advance when the respective subscriber station 10 is configured.

[0110] According to the first embodiment, the marking module 15, in particular the insertion block 152, is designed to overwrite the bit NACK as marking 48 with N bits in order to carry out the marking 48 of the frame 450. Here, N is a natural number greater than or equal to 1.

[0111] According to a modification of the first embodiment, the marking module 15, in particular the insertion block 152, is designed to carry out an arbitration when superimposing. For this purpose, the subscriber station 10 carries out the following.

[0112] It has already been shown in Figure 10 The subscriber station 10 which has already sent a NACK as shown in

[0113] It is thus possible to reliably identify and inform the other subscriber stations in the bus system 1 when a "strange" frame 450 has been sent in the bus system 1 according to the first embodiment and the variants and modifications thereof described previously. It is thus possible to increase the data safety of the operation of the bus system 1 at high data transmission rates compared to the prior art. It is thus also possible to increase the safety of the operation of the superior technical device, in particular the vehicle or the industrial plant or the other technical device, compared to the prior art.

[0114] Figure 10 A marking 480 of a "strange" frame 450 according to a second embodiment is shown. At least one of the subscriber stations 10, 30 can be designed to carry out the marking 480 as an alternative to or in addition to the marking 48 according to the previous embodiments. In the following only reference is made to the subscriber stations 10 for the sake of simplicity, even if the following explanations can likewise be used in the subscriber stations 30.

[0115] Unlike the first embodiment, the marking module 15, in particular the insertion module 152, is designed to insert the marking 480 after the frame 450. The marking 480 is thus not sent in the frame 450. The NACK bit and the NACK-dlm bit can thus be optional bits. If the NACK bit and the NACK-dlm bit are present, the function of the bits NACK, NACK-dlm is the same in the current embodiment as the function of the ACK bit and the ACK-dlm bit.

[0116] In the current embodiment, marker 480 begins in the intermediate frame interval 458 (INT). The intermediate frame interval 458 (INT) has at least 3 bits in CAN.

[0117] The marker module 15 is therefore designed for, in particular, inserting marker 480 directly after frame 450. Figure 10 In the example, marker 480 is inserted starting from bit 2 of the intermediate frame interval 458 (INT). Therefore, each user station 10, 30, and especially their communication control devices 11, 31, or more precisely their protocol controllers, is designed to search for marker 480 in the intermediate frame interval 458 (INT) even after the reception of frame 450 has ended. User stations 10, 20, 30, and especially their communication control devices 11, 31, or more precisely their protocol controllers, can thus confirm whether the previously received frame 450 was classified as a "strange" frame 450 by any of the user stations 10, 30.

[0118] exist ​ In the example, insertion block 152 inserts a flag 480 (Overload Flag) of length M = 8 bits into the transmit signal TxD4 during the intermediate frame interval 458 (interval field). Because two flags 480 (overload flags) cannot overlap to this length M = 8 bits, this flag 480 is a variant used to non-destructively mark the "strange" frame 450. Any other length M is also possible, which cannot be generated by superimposing flags 480. The normal overload flag is 6 bits long.

[0119] Furthermore, modules 15 and 35 are constructed in the same manner as previously described with respect to the first embodiment or its modifications.

[0120] All previously described design options for user stations 10, 20, and 30, bus system 1, and the methods implemented in bus system 1 can be used individually or in all possible combinations. Features of the previously described embodiments and / or modifications thereof can be combined arbitrarily, in particular. The following modifications are particularly conceivable as an additional or alternative measure.

[0121] It is possible that at least one of the subscriber stations 10, 30, in particular their communication control devices 11, 31, more precisely their protocol controllers, can only recognize the meaning of the flag 48 or the flag 480 for the frame. In this way the meaning of the flags 48, 480 can be distinguished. Furthermore, the reaction of the at least one of the subscriber stations 10, 20, 30, in particular their communication control devices 11, 21, 31, more precisely their protocol controllers, to the flags 48, 480 has less differentiation possibilities.

[0122] It is possible that at least one of the subscriber stations 10, 20, 30, in particular their communication control devices 11, 21, 31, more precisely their protocol controllers, can only distinguish a part of the meaning of the flag 48 or the flag 480. The reaction of the at least one of the subscriber stations 10, 20, 30, in particular their communication control devices 11, 21, 31, more precisely their protocol controllers, to the flags 48, 480 therefore has less differentiation possibilities.

[0123] It is furthermore conceivable that a TX subscriber station, which receives the frames 450 from the bus 40, which it has sent to the bus 40, inserts the flag 48 or 480 into the frame 450 when the TX subscriber station recognizes a strange frame in the frame 450, which it receives instead of the expected frame 450, which corresponds to the sent frame 450. This is the case, in particular, when malware inserts flags 48, 480, which are classified as "strange" by the TX subscriber station. Even if the relevant subscriber station 10, 30 is a RX subscriber station and is therefore only a receiver of frames in the ongoing data phase 452, such malware can send something to the bus 40, for example not only in the NACK bit, but also in other parts of the frame 450 itself and thus falsify the frame 450, which is sent by the TX subscriber station to the bus 40. The TX subscriber station can recognize this and therefore already equip the frame 450 with at least one corresponding flag 48, 480. Furthermore, or alternatively, the malware can even be active on the TX subscriber station and send falsified messages. The flag module 15, which ideally cannot be manipulated by malware, inserts at least one flag 48, 480, if necessary or in this case.

[0124] Even if the present application has been described so far by way of example with a CAN bus system, the present application can be used in any kind of communication network and / or communication method, which uses two different communication phases, in which the resulting bus states for the different communication phases are different. The present application can be used, in particular, in the development of other serial communication networks, such as Ethernet and / or 10Base-T1 S Ethernet, fieldbus systems, etc.

[0125] The bus system 1 according to the described embodiment can be, inter alia, a communication network in which data can be transmitted serially with two different bit rates. Advantageously, but not mandatorily, in the bus system 1 exclusive, collision-free access of the subscriber stations 10, 20, 30 to the common channel is ensured at least for specific time periods.

[0126] The number and arrangement of the subscriber stations 10, 20, 30 in the bus system 1 according to the described embodiment are arbitrary. In particular, the subscriber station 20 can be dispensed with in the bus system 1. It is possible for one or more of the subscriber stations 10 or 30 to be present in the bus system 1. It is conceivable for all of the subscriber stations in the bus system 1 to be designed identically, i.e. for there to be only subscriber stations 10 or only subscriber stations 30.

Claims

1. User stations (10; 20; 30) for a serial bus system (1), equipped with Used to control communication between user stations (10; 20; 30) and at least one other user station (10; 20; 30) of the bus system (1) and to generate transmission signals (TxD; TxD1; TxD2; TxD2) according to frames (450). Communication control devices (11; 21; 31) for TxD3; TxD4) Transmitting / receiving devices (12; 22; 32) are designed to transmit signals (TxD; TxD1; TxD2; TxD2) generated by communication control devices (11; 21; 31). TxD3; TxD4) are serially transmitted to the bus (40) of the bus system (1), and are designed to receive signals serially from the bus (40), and A tagging module (15; 25; 35) is used to evaluate whether a frame (450) received by the bus (40) should appear on the bus (40), and to tag the frame (450) with a tag (48; 480) such that the transmitting / receiving device (12; 22; 32) sends the tag (48; 480) to the bus (40) to notify at least one other user station (10; 20; 30) of the evaluation result. The tagging module (15; 25; 35) is designed to insert the tag (48; 480) into and / or after the frame (450) without destroying the frame (450).

2. The user station (10; 20; 30) according to claim 1, wherein, The marking modules (15; 25; 35) are designed to mark frames (450) that should not appear on the bus (40).

3. The user station (10; 20; 30) according to claim 1 or 2, wherein, The marking modules (15; 25; 35) are designed to evaluate, by comparison with a list, whether a frame (450) received by the bus (40) must be marked on the bus (40).

4. The user station (10; 20; 30) according to claim 1 or 2, wherein, The tagging module (15; 25; 35) is designed to insert the tag (48; 480) into the frame (450) after the data field (455) and to insert valid data of the frame (450) into the data field.

5. The user station (10; 20; 30) according to claim 1 or 2, wherein, The tagging module (15; 25; 35) is designed to insert the tag (48; 480) as a tag with a time length of N bits into the frame (450). Where N is a natural number greater than or equal to 1.

6. The user station (10; 20; 30) according to claim 5, wherein, The marking module (15; 25; 35) is designed to select the length of the mark (48; 480) based on the meaning of the mark (48; 480).

7. The user station (10; 20; 30) according to claim 1 or 2, wherein, The marker module (15; 25; 35) is designed to insert the marker (48; 480) after the frame (450) starting from the second position of the intermediate frame spacing (458).

8. The user station (10; 20; 30) according to claim 7, wherein, The marker (48; 480) has a length greater than the maximum length of the overload marker that can be sent in the intermediate frame interval (458).

9. The user station (10; 20; 30) according to claim 1 or 2, wherein, Designed to transmit signals (TxD; TxD1; TxD2; TxD3) generated by the communication control device (11; 21; 31). TxD3; TxD4) are serially transmitted to the transmitting / receiving device (12; 22; 32) on the bus (40) of the bus system (1), such that for the frame (450), the bit time (t_bt1) of the signal transmitted to the bus (40) in the first communication phase (451) can be different from the bit time (t_bt2) of the signal transmitted in the second communication phase (452).

10. The user station (10; 20; 30) according to claim 1 or 2. in, The frame (450) is constructed to be compatible with CAN FD, and In the first communication phase (451), it is agreed which of the user stations (10, 20, 30) of the bus system (1) will obtain at least temporary exclusive, conflict-free access to the bus (40) in the subsequent second communication phase (452).

11. User stations (10; 20; 30) for a serial bus system (1), equipped with Used to control communication between user stations (10; 20; 30) and at least one other user station (10; 20; 30) of the bus system (1) and to generate transmission signals (TxD; TxD1; TxD2; TxD2) according to frames (450). Communication control devices (11; 21; 31) for TxD3; TxD4) Transmitting / receiving devices (12; 22; 32) are designed to transmit signals (TxD; TxD1; TxD2; TxD2) generated by communication control devices (11; 21; 31). TxD3; TxD4) are serially transmitted to the bus (40) of the bus system (1), and are designed to receive signals serially from the bus (40), and A tagging module (15; 25; 35) is used to evaluate whether a frame (450) received by the bus (40) should appear on the bus (40), and to tag the frame (450) with a tag (48; 480) such that the transmitting / receiving device (12; 22; 32) sends the tag (48; 480) to the bus (40) to notify at least one other user station (10; 20; 30) of the evaluation result. The marking module (15; 25; 35) is designed to insert the mark (48; 480) as a reverse bit at the NACK position set for the user station (10; 20; 30) of the bus system (1) into the frame (450), indicating that the frame (450) was not received correctly, and The marking modules (15; 25; 35) are designed to insert in the frame (450) a mark (48; 480) that is longer in time than the set time length for displaying that the frame (450) was not properly received.

12. Bus system (1), with Bus (40), and At least two user stations (10; 20; 30) are interconnected via a bus (40) so that they can communicate with each other serially and at least one of the user stations (10; 20; 30) is a user station (10; 20; 30) according to any one of claims 1 to 11.

13. A method for communication in a serial bus system (1), wherein, The method is implemented using user stations (10; 20; 30) of a bus system (1), each user station having a communication control device (11; 21; 31), a transmitting / receiving device (12; 22; 32), and a tagging module (15; 25; 35), wherein the method comprises the following steps: The communication control device (11; 21; 31) controls the communication between the user station (10; 20; 30) and at least one other user station (10; 20; 30) of the bus system (1), wherein the communication control device (11; 21; 31) is designed to generate transmission signals (TxD; TxD1; TxD2; TxD3; TxD4) according to the frame (450). The transmitting / receiving devices (12; 22; 32) serially transmit the transmission signals (TxD; TxD1; TxD2; TxD3; TxD4) generated by the communication control device (11; 21; 31) to the bus (40) of the bus system (1). Signals are received serially from bus (40) of bus system (1) using transmitting / receiving devices (12; 22; 32). The flag module (15; 25; 35) is used to evaluate whether a frame (450) received from the bus (40) should appear on the bus (40), and The frame (450) is marked with a tag (48; 480) by the tagging module (15; 25; 35), such that the transmitting / receiving device (12; 22; 32) sends the tag (48; 480) onto the bus (40) to notify at least one other user station (10; 20; 30) of the evaluation results of the bus system (1). The tagging module (15; 25; 35) is designed to insert the tag (48; 480) into and / or after the frame (450) without destroying the frame (450).

Images