Responder station for a serial bus system, commander station for the serial bus system and method for communication in a serial bus system

Abstract

A responder subscriber station (101 ... 101N) for a serial bus system (1), a commander subscriber station (100) for the serial bus system (1), and a method for communication in a serial bus system (1) are provided. The responder subscriber station (101 ... 101N) has a communication control device (21) for controlling communication between the subscriber station (101; 102; ... 101N) and a commander subscriber station (100) of the bus system (1) and for evaluating at least one signal (VDIFF;RxD) based on a predetermined frame (460), in which the bit time (t_bt1) in a first communication phase (451) can differ from a bit time (t_bt2) in a second communication phase (452), wherein a field (ADH) can be present in the frame (460) for switching the first bit time (t_bt1) and a first physical layer (451_P) in a first communication phase (451) into a second bit time (t_bt2) and a second physical layer (452_P) in a second communication phase (452), and a synchronization module (25) for synchronizing the communication control device (21) to the signal (VDIFF; RxD) received from the bus (40), wherein the synchronization module (25) is designed to switch off its synchronization function when the communication control device (21) is to act as a transmitter of the frame (460), so that the responder subscriber station (101; 102; ... 101N) is the transmitter of the signal (VDIFF; RxD) received from the bus (40);

Description

Technical FieldThe present invention relates to a responder subscriber station for a serial bus system, a commander subscriber station for the serial bus system and a method for communication in a serial bus system.Prior ArtBus systems are used in many fields of technology for communication between technical devices, such as sensors and control devices.It is known to use classic CAN and / or CAN FD for the communication between devices in vehicles and / or in other technical devices, both of which are standardized in the international standard ISO11898-1:2015. With CAN FD, a communication on the bus is possible with, for example, 2 Mbit / s or 5 Mbit / s. Here, 64 bytes can be sent per message on the bus.In addition, CAN XL compatible with CAN FD specified in ISO / DIS11898-1:2023 may be used. With CAN XL, communication on the bus is possible with bit rates up to 20 Mbit / s and with an amount of data per message of up to 848 bytes.The subscriber stations of such a bus system are also called nodes. Subscriber stations of this type have a microcontroller which, in the case of CAN XL, supports all functions of the abovementioned standards for classic CAN and / or CAN FD and / or CAN XL.CAN XL offers the great advantage that data can be exchanged between subscriber stations of the bus system at a significantly higher speed than in the case of classic CAN or in the case of CAN FD. However, the demands on communication devices for carrying out communication with CAN XL and thus their costs are higher than for communication devices designed only for classic CAN and / or CAN FD.The cost aspect is particularly disadvantageous with respect to subscriber stations which have to perform only very simple function(s). Such subscriber stations are, for example, a warning light, in particular a light-emitting diode (LED), which is to be switched on or off under the control of the microcontroller of another subscriber station and / or is to change its color as required. Another example is a sensor which is intended to deliver its detection data from time to time to the microcontroller of another subscriber station.Therefore, it is desired to still take advantage of the advantages of CAN XL at lower cost for communication. For this purpose, it is considered to equip such subscriber stations with a smaller communication scope than others for carrying out such simple functions in a bus system. However, due to the complexity of CAN XL, this is not as readily possible.It would be possible to implement such subscriber stations as responders for carrying out such simple functions, which are assigned to a commander and can only communicate with the latter. A subscriber station having a microcontroller for controlling the responder is also referred to as a commander. However, communication devices for such responder subscriber stations and commander subscriber stations are not yet available for CAN XL at present.Disclosure of the InventionIt is therefore an object of the present invention to provide a responder subscriber station for a serial bus system, a commander subscriber station for a serial bus system and a method for communication in a serial bus system, which solve the aforementioned problems. In particular, a responder subscriber station for a serial bus system, a commander subscriber station for a serial bus system and a method for communication in a serial bus system are to be provided, in which communication in the serial bus system is possible with great robustness against errors and with a higher bit rate than previously and with a high net data transmission rate.This object is achieved by a responder subscriber station for a serial bus system having the features of claim 1. The responder subscriber station has a communication control device for controlling a communication of the subscriber station with a commander subscriber station of the bus system and for evaluating at least one signal received from a bus of the bus system on the basis of a predetermined frame, in which the bit time in a first communication phase can differ from a bit time in a second communication phase, wherein a field can be present in the frame for switching the first bit time and a first physical layer in a first communication phase into a second bit time and a second physical layer in a second communication phase, and a synchronization module for synchronizing the communication control device to the signal received from the bus, wherein the synchronization module is configured to switch off its synchronization function if the communication control device is intended to act as a transmitter of the frame, so that the responder subscriber station is the transmitter of the signal received from the bus.The described subscriber station (responder) has a simplified CAN XL controller, whereby a cost-effective integration of the responder on a single ASIC in a mixed semiconductor process is possible, such as bipolar transistor(s) and CMOS transistor(s) and DMOS transistor(s) (BCD technology). After the command from the commander, the responder subscriber station (responder) sends its functional information, for example a sensor value etc., with a CAN XL message to the commander subscriber station (commander).The described responder subscriber station is usable for CAN-XL light communication with a commander subscriber station with bit rates that are higher than the currently possible bit rates with CAN FD. In particular, the bit rates are greater than 10 Mbit / s, in particular up to 20 Mbit / s. Significantly higher bit rates are thus possible with the responder subscriber station than with CAN-FD light, in which only 2 Mbit / s or 5 Mbit / s can be achieved.In addition, with the described responder subscriber station, much larger data packets per message, namely 2 kbytes, can be transmitted over the bus than in the case of a CAN-FD light, in which only 64 bytes are permitted.A very great advantage of the described responder subscriber station is greatly reduced cost at the system level. One reason for this is that there is no need for a highly accurate clock in the responder subscriber station, since no arbitration is necessary. The clock may be up to 5 times more inaccurate than CAN XL. Another reason for the greatly reduced costs is that a protocol controller with a significantly reduced range of functions can be used in the responder subscriber station, which enables a saving of approximately 50%. Yet another reason for the greatly reduced cost is that no changes to the CAN XL transmitter / receiver (transceiver) or CAN SIC XL transmitter / receiver (transceiver) are required in the responder subscriber station. That is, the described responder subscriber station may use the CAN SIC XL transmitter / receiver (transceiver) specified for CAN XL according to the international standard ISO / DIS11898-2:2023 for bit rates up to 20 Mbit / s.It is also advantageous that, depending on the operating mode, the described responder subscriber station can also be used to use an existing CAN controller which is specified for CAN XL according to the international standard ISO / DIS11898-1:2023 and ISO / DIS11898-2:2023.Overall, the described subscriber station contributes to making the bus system more cost-effective at data rates of up to 20 Mbit / s and data packets of approximately 2 kbytes in a message, but nevertheless to making possible a robust or reliable CAN communication.Advantageous further embodiments of the subscriber station are specified in the dependent claims.In a variant, the synchronization module is configured to disable its synchronization function when the bit time of the first communication phase of the predetermined frame has a predetermined value corresponding to a bit rate greater than a predetermined bit rate and when the communication control means is to act as a transmitter of the frame, so that the responder subscriber station is the transmitter of the signal received from the bus.In one embodiment, the synchronization module has a synchronization block which is configured to synchronize the communication control device with the signal received from the bus, and a configuration block in which a value for at least one synchronization configuration bit is stored which indicates whether the bit rate is greater than the predetermined bit rate.The synchronization module may also have an evaluation block for evaluating the value of the at least one configuration bit, and a switching block for switching on or switching off the synchronization of the synchronization block on the basis of the evaluation of the evaluation block.The responder subscriber station may be a subscriber station configured to communicate according to CAN XL, wherein the predetermined frame is a CAN XL frame in the XBFF format.It is conceivable that the predetermined bit rate is 1 Mbit / s.The aforementioned object is also achieved by a commander subscriber station for a serial bus system having the features of claim 7. The commander subscriber station has a communication control device for controlling a communication of the subscriber station with a responder subscriber station of the bus system and for evaluating at least one signal received from a bus of the bus system on the basis of a predetermined frame, in which the bit time in a first communication phase can differ from a bit time in a second communication phase, wherein a field can be present in the frame for switching a first physical layer in the first communication phase into a second physical layer in the second communication phase. The commander subscriber station also has a synchronization module for synchronizing the communication control device to the signal received from the bus, wherein the synchronization module is configured to switch off its synchronization function if the bit time of the first communication phase of the predetermined frame has a predetermined value corresponding to a bit rate which is greater than a predetermined bit rate and if the communication control device is to act as a transmitter of the predetermined frame, so that the commander subscriber station is the transmitter of the signal received from the bus.The commander subscriber station described may support more than one frame format. Consequently, in the commander subscriber station, in particular by setting the value of a configuration bit, the synchronization function can be switched off or on, as mentioned above, for example. If the synchronization is switched off, the commander subscriber station no longer supports arbitration and can therefore only still be used as a commander.Nevertheless, when the synchronization function is enabled during transmission, the commander subscriber station can also communicate and arbitration with a normal CAN XL or CAN FD subscriber station on the bus.Advantageous further embodiments of the subscriber station are specified in the dependent claims.In the commander subscriber station described above, the synchronization module may comprise a synchronization block configured to synchronize the communication controller with the signal received from the bus and a configuration block storing a value for at least one synchronization configuration bit indicating whether the bit rate is greater than the predetermined bit rate.In addition, the synchronization module of the commander subscriber station can have an evaluation block for evaluating the value of the at least one configuration bit, and a switching block for switching on or switching off the synchronization of the synchronization block on the basis of the evaluation of the evaluation block.The commander subscriber station described above may be a CAN XL subscriber station, wherein the predetermined frame is a CAN XL frame in the XBFF format.It is conceivable that in the previously described commander subscriber station the predetermined bit rate is 1 Mbit / s. The previously described commander subscriber station and at least one previously described responder subscriber station can be part of a bus system which has a bus and at least two subscriber stations which are connected to one another via the bus in such a way that they can communicate with one another in series, wherein each of the at least two subscriber stations additionally has a transmitting / receiving device for transmitting a transmission signal to the bus of the bus system and / or for receiving a signal from the bus of the bus system.The bus system can also have at least one third subscriber station which is designed to transmit and / or receive signals on the basis of a frame, wherein the at least one third subscriber station has a communication control device which is designed to negotiate with the commander subscriber station in a first communication phase of the frame whether the third subscriber station or the commander subscriber station receives an at least temporarily exclusive, collision-free access to the bus in a subsequent second communication phase.The aforementioned object is also achieved by a method for communication in a serial bus system according to claim 14. The method is carried out with a previously described commander subscriber station and a previously described responder subscriber station.The method offers the same advantages as mentioned above with respect to the subscriber stations.It is possible in the method that, in contrast to a CAN XL subscriber station, the commander subscriber station and the responder subscriber station do not perform bit monitoring when transmitting a message, that the commander subscriber station does not transmit an ACK bit if the commander subscriber station has correctly received a message, that the responder subscriber station does not transmit an ACK bit if the responder subscriber station has correctly received a message, that the responder subscriber station does not perform error signaling, that the responder subscriber station does not use overload frames, that the responder subscriber station does not perform automatic retransmission, and that the responder subscriber station does not perform automatic shutdown of the responder subscriber station upon detecting a predetermined number of communication errors.Further possible implementations of the invention also include combinations, not explicitly mentioned, of features or embodiments described above or below with respect to the exemplary embodiments. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.DRAWINGSThe invention is described in more detail below with reference to the accompanying drawing and on the basis of exemplary embodiments. The following are shown: FIG. 1 shows a simplified block diagram of a bus system according to a first exemplary embodiment; FIG. 2 shows the format of CAN FD frames according to the aforementioned standard ISO11898-1:2015 for a message which can be transmitted by a transmitting / receiving device for a subscriber station of the bus system according to the first exemplary embodiment; FIG. 3 shows the format of CAN XL frames according to the ISO / DIS11898-1:2023 standard for a message which, as an alternative to the CAN FD frame of FIG. 2, can be transmitted by a transmitting / receiving device for a subscriber station of the bus system according to the first exemplary embodiment; FIG. 4 shows a simplified schematic block diagram of a first subscriber station (commander) of the bus system according to the first exemplary embodiment; FIG. 5 shows a time profile of a digital transmission signal during operation of the bus system at the first subscriber station, which is connected to the same bus of the bus system by at least one second subscriber station; FIG. 6 shows a time profile of bus signals CAN_H and CAN_L at the first subscriber station according to the first exemplary embodiment; FIG. 7 shows a time profile of a differential voltage VDIFF of the bus signals CAN_H and CAN_L in the first subscriber station according to the first exemplary embodiment; FIG. 8 shows a time profile of a digital reception signal which the first or a second subscriber station generates from a signal received from the bus, which signal is based on the transmission signal from FIG. 5 ; and FIG. 9 shows an example of the ideal temporal profile of bus signals CAN_H, CAN_L which are sent from subscriber stations of the bus system to a bus of the bus system for the message from FIG. 3 ; FIG. 10 shows the time profile of a differential voltage VDIFFwhich forms on the bus of the bus system as a result of the bus signals from FIG. 9; FIG. 11 shows an example of a temporal profile of a digital transmission signal which is to be converted in an arbitration phase (SIC operating mode) into bus signals CAN_H, CAN_L for a bus of the bus system from FIG. 1 ; FIG. 12 shows the time profile of the bus signals CAN_H, CAN_L when changing between a recessive bus state to a dominant bus state and back to the recessive bus state, which are sent to the bus in the arbitration phase (SIC operating mode) on the basis of the transmission signal from FIG. 5 ; and FIG. 13 shows a simplified schematic block diagram of a second subscriber station (responder) of the bus system according to the first exemplary embodiment.In the figures, identical or functionally identical elements are provided with the same reference numerals, unless otherwise indicated.DESCRIPTION OF THE EMBODIMENTSFIG. 1 shows as an example a bus system 1, which is designed in particular fundamentally for a CAN bus system, a CAN FD bus system, a CAN XL bus system and / or modifications thereof, as described below. The bus system 1 can be used in a vehicle, in particular a motor vehicle, an aircraft, etc., or in a hospital, etc.In FIG. 1, bus system 1 has a bus 40 to which a commander subscriber station 100 and a plurality of responder subscriber station(s) 101, 102, 103... 10N. N is a natural number greater than or equal to 1. Additionally, a subscriber station 30 is optionally connected, which may be a conventional classic CAN subscriber station or a conventional CAN FD subscriber station or a conventional CAN XL subscriber station.On the bus 40 there are 1 to N responder subscriber stations 101, 102, 103... 10N. The bus 40 may have a first bus wire 41 (FIG. 4 ) and a second bus wire 42 (FIG. 4 ), which are not illustrated in FIG. 1. The bus cores can also be called CAN_H and CAN_L and serve for electrical signal transmission after coupling in the dominant levels or generating recessive levels or other levels for a signal in the transmission state.The commander subscriber station 100 is, for example, a control unit of a motor vehicle or of another technical installation, as described in more detail below. The responder subscriber stations 101, 102, 103... 10N may include, for example, at least one sensor or at least one display device or at least one actuator or at least one encoder, etc., of a motor vehicle or other technical installation, as described in more detail below.As shown in FIG. 1, the commander subscriber station 100 has a communication control device 11, a transmitting / receiving device 12 and a synchronization module 15. 10N has a communication control device 21, a transmitting / receiving device 22 and a synchronization module 25.The transmitting / receiving devices 12, 22, 32 of the subscriber stations 100... 10N and the subscriber station 30 are each connected directly to the bus 40, although this is not illustrated in FIG. 1.The commander subscriber station 100 is configured to generate messages 45, 46 in the form of signals. However, the commander subscriber station 100 is configured to only send messages 46 in the form of signals to one of the subscriber stations 101... 10N via the bus 40. Message 46 is partially constructed in the same manner as message 45 as described in more detail with respect to Figures 2 and 3.The subscriber stations 101... 10N in FIG. 1 are configured to generate messages 46 in the form of signals and to transmit them to the commander subscriber station 100 via the bus 40. Messages 46 can be transmitted serially between subscriber station 100 and one of subscriber stations 101 to 10N.The at least one optional subscriber station 30 is configured to generate messages 45, 46 in such a way that communication with the commander subscriber station 100 via the bus 40 is possible. However, the communication is configured such that the at least one optional subscriber station 30 communicates between responder subscriber stations 101, 102, 103... 10N and commander subscriber station 100 do not interfere. This can be done in various ways, A) by means of a timing, or B) by the selection of appropriate identifiers, so that optional subscriber station 30 arbitrates with a responder subscriber station 101, 102, 103... 10N always loses. This is described in more detail below.The communication control devices 11, 21 each serve to control a communication of the subscriber station 100 via the bus 40 with one of the subscriber stations 101... 10N. The communication control devices 11, 21 generate a transmission signal TxD if necessary, which is described in more detail below with reference to FIG. 5. In addition, the communication controllers 11, 21, 31 read or decode a received signal RxD, which is described in more detail below with reference to FIG. 8.The communication control device 11 can be designed, at least in part, as a conventional CAN-XL controller according to ISO / DIS 11898-1:2023. Thus, the communication controller 11 supports transmission and / or reception of 7 different frame formats, namely 4 classic CAN frame formats, 2 CAN-FD frame formats having identifiers of 11 bits or 29 bits, and 1 CAN XL frame format.The communication control device 31 can be embodied as a conventional CAN-XL controller according to ISO / DIS 11898-1:2023. Therefore, the communication controllers 11, 31 can communicate with each other as usual in Classic CAN or CAN FD or CAN XL.By way of example, FIG. 2 shows a CAN-FD frame 450 with 29 bit identifier, which the subscriber station 100 can use for communication with messages 45 via the bus 40 with the subscriber station 30. The CAN FD messages 45 may comprise a number of 0 up to 64 data bytes which are transmitted at a significantly faster data rate than in the case of a classic CAN message.The communication control device 11 of FIG. 1 is designed to communicate with the subscriber station 101... 101N uses a CAN-XL message 46. For transmitting and receiving the CAN-XL message 46, the respective synchronization modules 15, 25 are optionally used. The CAN XL message 46 is constructed based on a CAN XL format, which is described in more detail with respect to FIG. 3. The synchronization modules 15, 25 are only required from a bit rate of greater than 1 Mbit / s.The communication control device 11 thus creates and reads a first message 45 or a second message 46, wherein the first and second messages 45, 46 differ by their data transmission standard, namely CAN FD and CAN-XL in this case.The communication control device 21 is designed as a CAN-XL light controller. In addition, the synchronization module 25 is present, which is configured to be compatible with the synchronization module 15. The communication control device 21 generates second messages 46, for example CAN-XL messages 46, and is configured to read messages 46.For communication with one of the subscriber stations 101... In FIG. 10N, the subscriber station 100 (commander) sends a transmission call to the desired subscriber station 101... via the bus 40. 10N. The polling is performed by transmitting a message 46 based on a CAN XL frame 460 shown in FIG. 3. A responder subscriber station 101... In FIG. 10N, a message 46 based on a CAN-XL frame according to FIG. 3 is only sent to the commander subscriber station 100 via the bus 40 if the subscriber station 100 comprises the subscriber station 101... 10N has requested this by a request to send. The request for transmission is encoded in the frame 460 transmitted by the subscriber station 100 (commander).In the CAN XL light bus access method, the subscriber station 100 (commander) only starts communication with the responders. For this purpose, the subscriber station 100 (commander) sends a message 46 in a frame according to FIG. 3. After completion of the message 46, the subscriber station 100 (commander) eliminates a certain time window to the responder, in which one of the N responder subscriber stations 101...10N can send a message 46 and thereby answer the transmission call.Thus, the subscriber station 100 has in relation to the subscriber stations 101... 10N illustrates the function of a commander / interrogator and each of the subscriber stations 101... 10N has the function of a responder. Therefore, the subscriber station 100 is also referred to as a CAN-XL light commander below and the subscriber station 101... 10N is referred to as a CAN-XL light responder.FIG. 2 shows a frame 450 that can be created by the subscriber station 100 for a message 45 with up to 64 data bytes in the CAN FD FEFF format as an example. The CAN FD frame 450 can be provided by the communication control device 11, namely encoded in a digital transmission signal TxD, to the associated transmitting / receiving device 12 for transmission on the bus 40 to another subscriber station of the bus system 1, for example the subscriber station 30.Frame 450 is divided into two communication phases called arbitration phase 451 (first communication phase) and data phase 452 (second communication phase). Frame 450 begins and ends in arbitration phase 451. Frame 450 begins with an SOF bit and has an arbitration field 453 (arbitration field), a control field 454 (control field), a data field 455 (data field), a checksum field 456 (CRC field), an acknowledge field 457 (ACK= Ack), and an end-of-frame field EOF (EOF=End of Frame).Bits in arbitration phase 451 of frame 450 may have a longer bit time than bits of data phase 452, as illustrated in FIG. 2 as an example. The switching from the bits with the bit time of the arbitration phase 451 to the bits with the bit time of the data phase 452 takes place in the BRS bit, at the location which is marked SP in FIG. 2. SP stands for sample point, which means sampling time.Bits indicated by a thick dash at their lower line in Fig. 2 are transmitted as dominant or '0' in the frame 450. Bits indicated by a thick dash at the top line thereof in Fig. 2 are transmitted as "recessive" or "1" in the frame 450. Such bits, shown in FIG. 2 with a thick dash, have a predetermined fixed value in frame 450.The arbitration field 453 contains an identifier (identifier) of the frame 450 divided into the two fields ID field and ID ext field. The identifier has 29 bits. Between the ID field and the ID ext field, an SRR bit and an IDE bit are provided. At the end of arbitration field 453, an RRS bit is located. FIG. 2 shows the FEFF format with the 29-bit extended identifier. Alternatively, the commander subscriber station 100 or optional subscriber station 30 may use a different CAN FD frame format, in particular a modified frame 450 having an identifier of 11 bits.The control field 454 begins with an FDF bit followed by a res bit. This is followed by the BRS bit and an ESI bit. The ESI bit in frame 450 is the first bit with the bit time of data phase 452.The control field 454 terminates with a DLC field in which the length of the following data field 455 is encoded. The res bit must be sent for frame 450 with a logic value 0, in other words (logic) 0, i.e. dominant.Data field 455 is not present when the DLC field of control field 453 is 0. The data field 455 has a length corresponding to the value encoded in the DLC field. The value may be up to 64 bytes as mentioned previously.The checksum field 456 contains in a field SBC the number of stuff bits modulo 8 which were inserted into the frame 450 according to the bit stuffing rule, namely a bit inverse thereto is to be inserted in each case after five identical bits. In addition, the checksum field 456 contains a CRC checksum in a CRC field, which may also be called a CRC checksum, and ends with a CRC delimiter CRC Del that is connected thereto.The switching from the bits with the bit time of the data phase 452 to the bits with the bit time of the arbitration phase 451 takes place in the bit CRC-Del at the location which is marked SP in FIG. 2. SP stands for sample point, which means sampling time.The acknowledge field 457 contains a bit ACK slot in which subscriber stations, which are currently only receivers of the frame 450 but not transmitters of the frame, can acknowledge or cannot acknowledge the correct reception of the frame 450 from the bus 40. The acknowledge field 457 terminates with a bit ACK-Del, also called an ACK delimiter.In the end of frame field EOF, a bit sequence is provided which marks the end of frame 450. Thus, the end field bit sequence (EOF) serves to identify the end of frame 450. The end field (EOF), together with the ACK delimiter, provides that a number of 8 re-intensive bits is transmitted at the end of frame 450. This is a bit sequence that cannot occur within frame 450. This allows subscriber stations 100, 101... 10N and 30 the end of the frame 450 can be detected securely.After the end field (EOF) having 7 bits, an inter frame space (IFS) follows in the frame 450, which is not shown in FIG. 2. This interframe spacing (IFS) is designed in CAN FD to correspond to ISO11898-1:2015. The inter frame space (IFS) has at least 3 bits.Incidentally, the fields and bits mentioned are known from the 15011898-1:2015 and are therefore not described in any more detail here.In the arbitration phase 451 of CAN FD, the identifier (ID) with bits ID28 to ID0, for example, in the arbitration field 453 is used to negotiate bit by bit between subscriber stations 100 or other CAN FD subscriber stations on the bus 40, which subscriber station 100 wishes to send the message 45 with the highest priority and therefore receives exclusive access to the bus 40 of the bus system 1 for the next time to send in the subsequent data phase 452. In arbitration phase 451, a physical layer is used as in CAN and CAN-FD. The physical layer corresponds to the physical layer or layer 1 of the known OSI (open systems interconnection) model.The subscriber stations 101... 10N as CAN XL light responder subscriber stations, more specifically their communication control device 21, do not support arbitration, as mentioned above and as described in more detail below. If no subscriber station 30 is present on bus 40, but only a commander and its responder, no arbitration takes place on bus 40.In order to manage without the CAN arbitration, in which the known CSMA / CR method resolves a collision when two CAN nodes (subscriber stations) start a message at the same time, the commander must specify when which responder is allowed to send a message. That is, if the commander requested a particular responder to send by polling, the commander waits a user-specified time until the responder has responded before the commander sends any other message. If a responder who has received a poll but has not yet started its response sees the beginning of another message on the CAN bus 40, he regards its poll as completed and does not transmit its message 46. The response times of the various responders in the CAN system are known to the commander.Collisions of frames on bus 40 between CAN XL light responders (subscriber stations 101...10N) and any other CAN nodes present, such as subscriber station 30, that contain the arbitration function can also be avoided as follows. For this purpose, the responders for transmission are assigned identifiers with a higher arbitration priority. This will cause the other subscriber stations, if they start a message simultaneously with a responder, to lose arbitration and become the receiver.The subscriber station 100 as the transmitter of a message 45, 46 only starts transmitting bits of the data phase 452 onto the bus 40 if the subscriber station 100 as the transmitter has gained arbitration and the subscriber station 100 as the transmitter therefore has an exclusive access to the bus 40 of the bus system 1 for transmission. The same applies to each CAN subscriber station 30 which is connected to the bus 40 and wishes to send a message 45, 46 to the bus 40.FIG. 3 shows a CAN XL frame 460 for the message 46, as it is transmitted from a subscriber station 100 or a subscriber station (responder) 101... 10N or its communication control device 21, namely encoded in a digital transmission signal TxD, is provided to the associated transmitting / receiving device 11, 22 for transmission on the bus 40. Here, the communication controller 21 creates the frame 460 in the present embodiment as compatible with CAN FD, as also illustrated in FIG. 3.Referring to FIG. 3, the CAN XL frame 460 for the CAN communication on the bus 40 is also divided into different communication phases 451, 452, namely the arbitration phase 451 and the data phase 452. After a start bit (SOF), the frame 460 has an arbitration field 463, a control field 464 with an ADS field for switching between the communication phases 451, 452, a data field 465, a checksum field 466 and a frame termination field 467. The end of frame field EOF follows, as in a frame 450 according to FIG. 2. the CAN XL format is defined in the ISO / DIS11898-2:2023.In arbitration phase 451, arbitration is also performed for frame 460 of FIG. 3 using the identifier (ID), as previously described with respect to FIG. 2 for the various bus configurations. In arbitration phase 451, an arbitration bit rate less than or equal to 1 Mbit / s is used in the present embodiment. If no subscriber station 30 is present on bus 40, no arbitration takes place on bus 40.According to FIG. 3, in the data phase 452, in addition to a part of the control field 464 of the frame 460, the payload data of the CAN-XL frame 460 or of the message 46 from the data field 465 and the checksum field 466 are transmitted. In the data phase 452, in the present embodiment, a data bit rate is used, which may have values of in particular up to 20 Mbit / s.After the data phase 452, the DAS field in CAN XL of FIG. 3 follows, which serves to switch from the data phase 452 back to the arbitration phase 451.n of the CAN XL data phase 452 can be used, when corresponding transmitting / receiving devices for CAN XL are used, for the transmission on the bus 40, symmetrical '1' and '0' levels, instead of a re-intensive and dominant level as in the case of CAN FD.Generally, two different shuffling rules are applied in the creation of the frame 460. Until before the FDF bit in the arbitration field 453, the dynamic bit shuffling rule of CAN FD or for a frame 450 of FIG. 2 applies, so that after 5 identical bits in sequence a stuff bit inverse thereto is to be inserted. In the data phase 452 up to before the FCP field, a fixed shuffling rule applies, so that after a fixed number of bits a fixed shuffling bit is to be inserted which is inverse to the preceding bit.In the present embodiment, the res bit known from CAN FD, designated XLF bit in frame 460, is used for switching from the CAN FD format to the CAN XL format. Therefore, the framing formats from CAN FD and CAN XL to res bit and XLF bit are the same. A receiver does not recognize the format in which frame 460 is transmitted until this bit. If the bit is transmitted as 1, i.e. re-intensive, it is the XLF bit and thus identifies the frame 460 as a CAN XL frame. For a CAN FD frame of FIG. 2, the communication control device 11, 31 sets the bit as 0, i.e., as a dominant res bit. A CAN XL subscriber station, i.e. here the subscriber stations 30, 100, also supports CAN FD. The subscriber stations 101... 10N, on the other hand, are designed for CAN XL light and support exclusively frames 460 (CAN XL format) in transmission and reception.Following the XLF bit in frame 460 is a resXL bit, which is a dominant bit for future use. The resXL must be sent as 0 for frame 460, i.e., dominant.The resXL bit is followed in frame 460 by a sequence ADS (arbitration data switch) in which a predetermined bit sequence is encoded. This bit sequence allows a simple and reliable switch from the bit rate of the arbitration phase 451 (arbitration bit rate) to the bit rate of the data phase 452 (data bit rate). Optionally, within the ADH bit, the operating mode of the transmitting / receiving device 12, 22, 32 is switched from the operating mode B_451 (SLOW or SIC) of the arbitration phase 451 into one of two operating modes B_452_TX (FAST_TX), B_452_RX (FAST_RX) of the data phase 452. The two modes of data phase 452 are a B_452_TX (FAST_TX) mode for a transmitting node that is allowed to transmit its signal on bus 40 in data phase 452 and a B_452_RX (FAST_RX) mode for a receiving node that is only receiver of the signal from bus 40. In order to achieve data bit rates of up to 20 Mbit / s, the physical layer, i.e. the operating mode of the transceiver device 12, 22, 32, is switched from SLOW or SIC to FAST_TX or FAST_RX within the bit ADH. The switching of the physical layer is necessary when data bit rates of more than 8 Mbit / s are required or when a complex CAN bus topology is used, which is the case, for example, with long stubs.The following fields up to the beginning of the data fields 465 are not described in detail herein. The data field 465 may have up to 848 bytes. The length of data field 465 is encoded in bits 0 through 10 of the DLC field.After the data field 465, the checksum field 466 with a frame checksum FCRC and an FCP field follows in the frame 460. Here, FCP=frame check pattern=frame check pattern. The FCP field consists of 4 bits, in particular with the bit sequence 1100. A receiving node checks, by means of the FCP field, whether the receiving node is bit synchronous with the transmission data stream. In addition, a receiving node synchronizes to the falling edge in the FCP field.After the FCP field, the frame termination field 467 follows. The frame termination field 467 consists of two fields, namely the DAS field and the acknowledgement field or ACK field with the at least one bit ACK and the bit ACK-Dlm.The DAS field contains the sequence DAS (Data Arbitration Switch) in which a predetermined bit sequence is encoded. The bit sequence DAH, AH 1, AL 1 allows a simple and secure switching from the data bit rate of the data phase 452 to the arbitration bit rate of the arbitration phase 451. In addition, during the DAS field, more precisely in the DAH bit, the operating mode of the transmitting / receiving device 12, 22, 32 is optionally switched from an operating mode B_452_TX (FAST_TX) or B_452_RX (FAST_RX) into the operating mode B_451 (SLOW or SIC). If the physical layer was previously switched, the physical layer is switched within bit DAH. Bit AH1 is followed by bit AL1 (logic 0) and bit AH2 (logic 1). The two bits DAH and AH1 ensure that there is enough time for the mode switching of the transmitting / receiving device 11 and that all subscriber stations 30, 100, 101 to 10N see a recessive level of significantly more than one arbitration bit time before the edge at the beginning of the AL1 bit (logic 0). This ensures reliable synchronization for the subscriber stations of the bus system.In the frame termination field 467, the sequence of the DAS field is followed by the acknowledgement field (ACK). Bits are provided in the acknowledge field to acknowledge or not acknowledge proper reception of frame 460.The frame termination field 467 is followed in the frame 460 by the frame end field (EOF=End of Frame), as in the case of CAN FD according to FIG. 2.The end of frame (EOF) field has a length for subscriber stations whose error signaling is not enabled and which transmit a CAN XL frame, which is different depending on whether a dominant bit or a recessive bit was seen in the ACK bit. If the transmitting subscriber station has received the ACK bit as dominant, then the end of frame (EOF) field has a number of 7 re-intensive bits. Otherwise, the end of frame (EOF) field is only 5 recessive bits long.The end of frame (EOF) field is followed in frame 450 by an inter frame space (IFS) as explained above with reference to frame 450 of FIG. 2.Here, CAN XL is as follows.In contrast to CAN FD, the identifier ID of the frame 460 in CAN XL is called "priority ID".Unlike CAN FD, CAN XL may send the RRS bit as (logic) 0 or as (logic) 1. In CAN FD, the RRS bit is always sent as logic 0.FIG. 4 shows the basic structure of the subscriber station 100 with the communication control device 11, the transmitting / receiving device 12 and the synchronization module 15, which is part of the communication control device 11.According to FIG. 4, the subscriber station 100 (commander) has, in addition to the communication control device 11 and the transmission / reception device 12, a microcontroller 13, to which the communication control device 11 is assigned, and a system ASIC 16 (ASIC= Anwendungs-specific integrated circuit). The system ASIC 16 can alternatively be a system base chip (SBC), on which a plurality of functions necessary for an electronic module of the subscriber station 100 are combined. The system ASIC 16 has, in particular, an application 161, which can be designed as a computer program (app) or software. One such application is a technical application 161. The application 161 is, for example, any application in a vehicle. In particular, the application is a windscreen washer system and / or a driver assistance system, etc. For example, the windscreen washer system controls the movement of at least one windscreen wiper (actuator) using data of a rain sensor and / or wind sensor and or speed sensor and / or light sensor and / or a warning light (actuator) can be switched on or off. However, the application is not limited to a window washer or parts thereof.In addition to the transmitting / receiving device 12, an energy supply device 17 is installed in the system ASIC 16, which supplies the transmitting / receiving device 12 with electrical energy. The power supply 17 typically supplies a voltage CAN_Supp of 5 V. However, as necessary, the power supply 17 may supply another voltage having a different value. Additionally or alternatively, the energy supply device 17 can be designed as a current source.If the communication control device 11 acts as a CAN-XL light commander, the communication control device 11 creates a frame 460 in which a bit rate changeover can take place in the fields ADS, DAS of FIG. 3, as described above, and / or evaluates such a frame 460. For this purpose, a conventional CAN-XL communication control device according to ISO / DIS11898-1:2023 can be used for the device 11. As a result, a data bit rate with values of in particular up to 20 Mbit / s can be achieved in the data phase 452. In the communication controller 11 as the CAN-XL light commander, the bit rate switching may be turned on or off. Turned off means that the user sets the same bit rate for arbitration phase 451 and data phase 452.According to FIG. 4, the synchronization module 15 has a synchronization block 151, optionally a configuration block 152, optionally an evaluation block 153 and a switching block 154. In particular, a value for at least one synchronization configuration bit 1521 can be stored in optional configuration block 152. The synchronization block 151 may be the bit timing controller BTL of the communication controller 11.The synchronization module 15, in particular the evaluation block 153 and the switching block 154, can / can be embodied at least partially as software.The synchronization block 151 has a synchronization function described in ISO / DIS11898-2:2023. However, this synchronization function is switchable as needed, as described in more detail below.The transmitting / receiving device 12 has a transmitting module 121 and a receiving module 122. Although the transmission / reception device 12 is always discussed below, it is alternatively possible to provide the reception module 122 in a separate device externally to the transmission module 121. The transmission module 121 and the reception module 122 may be configured as in a conventional CAN-SIC-XL transmitter / receiver 12. The transmission module 121 can have, in particular, at least one operational amplifier and / or a transistor. The receiving module 122 can in particular have at least one operational amplifier and / or a transistor.The transmitting / receiving device 12 is connected to the bus 40, more precisely its first bus wire 41 for CAN_H and its second bus wire 42 for CAN_L. The voltage supply for the energy supply device 17 for supplying the first and second bus wires 41, 42 with electrical energy, in particular with the voltage CAN supply, takes place via at least one connection 43. The connection to ground or CAN_GND is realized via a connection 44. The first and second bus wires 41, 42 are terminated by a terminating resistor 49.The first and second bus wires 41, 42 are connected in the transmitting / receiving device 12 not only to the transmitting module 121, which is also referred to as transmitter, but also to the receiving module 122, which is also referred to as receiver, even if the connection is not shown in FIG. 4 for the sake of simplicity.During operation of bus system 1, transmission module 121 of FIG. 4 may convert a transmission signal TxD of communication control device 11, for example transmission signal TxD of FIG. 5, serially into corresponding signals CAN_H, CAN_L for CAN or CAN FD or CAN XL for bus cores 41, 42 and transmit these signals at the terminals for CAN_H and CAN_L onto bus 40.The communication controller 11 transmits the transmission signal TxD of FIG. 5 over time t (serial) to the transmission module 121 via the terminal TXD as shown in FIG. 4. As shown by way of example in FIG. 5, the transmit signal TxD has the voltage states H (high=high) and L (low=low) with a corresponding voltage U.According to the example of FIG. 6, the signals CAN_H and CAN_L for a frame 450 of FIG. 2 or frame 460 of FIG. 3 (without mode switching of the transmitting / receiving device) have the dominant and recessive bus levels 401, 402, as known from CAN, in the arbitration phase 451. A difference signal VDIFF=CAN_H-CAN_L is formed on bus 40, which is shown in FIG. 7 for arbitration phase 451. The individual bits of the signal VDIFF having the bit time t_bt 1 may be detected in the arbitration phase 451 and the data phase 452 having a reception threshold T_a of 0.7 V, for example. In the data phase 452 of a frame 450, the bits of the signals CAN_H and CAN_L may be transmitted faster, i.e. with a shorter bit time t_bt 2, than in the arbitration phase 451, as mentioned above. Thus, the signals CAN_H and CAN_L for CAN FD for frame 450 and CAN XL for frame 460 in data phase 452 differ from the conventional signals CAN_H and CAN_L at least in their faster bit rate.The sequence of the states H, L of the transmission signal TxD of FIG. 5 and the states 401, 402 resulting therefrom for the signals CAN_H, CAN_L in FIG. 6 and the profile of the voltage VDIFF of FIG. 7 resulting therefrom serves only to illustrate the function of the subscriber station 100. The sequence of data states for bus states 401, 402 may be selected as needed.The receiving module 122 forms a received signal RxD from signals CAN_H and CAN_L received from the bus 40, which are shown in FIG. 6, and from the differential voltage VDIFF of FIG. 7, respectively. For generating the digital receive signal RxD of FIG. 8, the receiving module 122 uses the receive thresholds T_A, etc., as described above. The receive signal RxD is shown in FIG. 8 without propagation delay. The receiving module 122 passes this received signal RxD to the associated communication control device 11, as shown in FIG. 4.If a CAN XL-capable subscriber station 30, 100, 101,..., 10N uses the mode switching of the transmitting / receiving device 12, 22, 32, which can be switched on / off by configuration according to ISO / DIS11898-1:2023, then the signals of FIGS. 9 and 10 apply to a message 46 based on a frame 460 of FIG. 3, instead of the signals of FIGS. 6 and 7.As shown in FIG. 9, the transmitting / receiving devices 12, 22, 32 use a first physical layer 451_P in the arbitration phase 451 to transmit a transmit signal TxD (FIG. 5 ) over time t as signals CAN_H, CAN_L onto the bus 40. In contrast, in the data phase 452 for data bit rates up to 20 Mbit / s, the transmitting / receiving device 12, 22, 32 may use a second physical layer 452_P, which is different from the first physical layer 451_P, to transmit the transmit signal TxD (FIG. 1 ) as signals CAN_H, CAN_L onto the bus 40, as already described above. For the physical layer 452_P, there are the two modes, namely FAST_TX and FAST RX, as described above.On the left-hand side, FIG. 9 shows that the subscriber stations 30, 100, 101,..., 10N in the arbitration phase 451 each transmit signals CAN_H, CAN_L over the time t onto the bus 40, which have a first bit duration t_bt 1. The signals CAN_H, CAN_L are serial signals and have alternately at least one dominant state 401, in which the situation applies to VCAN_H=3.5 V and to VCAN_L=1.5 V at a supply voltage VCC=5 V, or at least one recessive state 402, in which the situation applies to VCAN_H=VCAN_L=2.5. A dominant state 401 (dom) is driven in phase 451 in the case of NRZ coding of the transmission signal TXD if TXD=0 or LOW (LOW=Low) applies (FIG. 5 ). A re-intensive state 402 (rec) is generated or occurs during NRZ coding of the transmission signal TXD in phase 451 if TXD=1 or HI (HIGH) applies (FIG. 5 ). After arbitration in arbitration phase 451, i.e., if arbitration occurs between subscriber stations 30 and 100, one of the subscriber stations 30, 100 is fixed as a winning machine.If the communication control device of the respective subscriber station 30, 100, 101,..., 10N starts the signaling in the first switching field ADS of FIG. 3 for the switching from the first to the second communication phase 451, 452, the associated transmitting / receiving device 12, 22 switches its physical layer 451_P from a first operating mode (SLOW), which can alternatively be embodied as an SIC operating mode, into the physical layer 452_P of the data phase 452 at the end of the arbitration phase 451. To do so, the modes of operation of data phase 452 are enabled as previously described with respect to FIG. 3.As shown on the right side in FIG. 9, the transmission module 121 then generates the states LV 0 or LV 1 with the physical layer 452_P for the signals CAN_H, CAN_L on the bus 40 in succession and thus in series in the data phase 452 or in the second operating mode (FAST_TX) depending on a transmission signal TxD. The state LV 0 (VCAN_H=3.0 V, VCAN_L=2.0 V) is driven during a pulse width modulation (PWM coding) of the transmission signal TXD for a first PWM symbol in the transmission signal TXD. The state LV 1 (VCAN_H=2.0 V and VCAN_L=3.0 V) is driven in the pulse width modulation (PWM coding) of the transmission signal TXD for a second PWM symbol different from the first PWM symbol in the transmission signal TXD.The frequency of the signals CAN_H, CAN_L may be increased in the data phase 452. In the example of FIG. 9, for this purpose, the bit time or bit duration t_bt 2 in the data phase 452 is shorter or less than the bit time or bit duration t_bt 1 in the arbitration phase 451. Thus, the net data transfer rate in data phase 452 is increased in the example of FIG. 9 compared to arbitration phase 451.In contrast, for example, the transmitting / receiving device 32 of the subscriber station 30 switches its physical layer 451_P at the end of the arbitration phase 451 from the first operating mode (SLOW or SIC) into the physical layer 452_P of the data phase 452 for a third operating mode (FAST_RX) of the transmitting / receiving device 12, since the subscriber station 30 is only receiver, i.e. not transmitter, of the frame 450 in the data phase 452. The same applies to the responder subscriber stations 101...10N. Each of the subscriber stations 30, 100, 101,..., 10N may transmit and receive. Here, it is assumed only in the example that subscriber stations 30 and 101,..., 10N are receivers of the currently transmitted frame.If the transmitting / receiving device 12, in particular with the signaling in the second switching field DAS of FIG. 3, recognizes that a switching from the data phase 452 back into the arbitration phase 451 is to be carried out, the transmitting / receiving device 12 is switched from transmitting (operating mode FAST_TX) (and) or receiving (operating mode FAST_RX) signals with the physical layer 452_P to transmitting and / or receiving signals with the physical layer 451_P. Thus, after the end of the data phase 452, all the transceivers 12, 22, 32 switch their operating mode to the first operating mode (SLOW or SIC). Thus, all transmitting / receiving devices 12 can not only switch between the bit durations t_bt 1, t_bt 2 but also switch their physical layer, as described above.According to FIG. 10, in the arbitration phase 451 over time t, in the ideal case a difference signal VDIFF=CAN_H-CAN_L with values of VDIFF=2V for dominant states 401 (dom) and VDIFF=0V for recessive states 402 (rec) is formed on the bus 40. The plot of VDIFFin phase 451 is shown on the left side in FIG. 10. In contrast, in data phase 452, a difference signal VDIFF=CAN_H-CAN_L corresponding to states LV 0, LV 1 of FIG. 10 forms on bus 40 over time t, as shown on the right side in FIG. 10. The state LV0 has a value VDIFF=1V. The state LV1 has a value VDIFF = -1V.The receiving module 122 may distinguish the states 401, 402 with one of the receiving thresholds T 1, T 2, T 3, respectively, that are in the ranges TH_T 1, TH_T 2, TH_T 3. In order to evaluate the signals from the bus 40, the reception module 122 uses, in the arbitration phase 451, the reception threshold T 1 of, for example, 0.7 V, which may be equal to the reception threshold T_a in FIG. 7, in order to generate the reception signal RxD, and optionally the reception threshold T 2 of, for example, -0.35 V. In contrast, the reception module 122 uses, in the data phase 452, the reception threshold T 3 for evaluating the signals from the bus 40 in order to generate the reception signal RxD. In switching between the first to third modes (SLOW or SIC, FAST_TX, FAST_RX) described above with reference to FIG. 9, the receiving module 122 switches the receiving thresholds T 2, T 3, respectively, as shown in FIG. 10.The reception thresholds T1 and T2 serve to identify whether the bus 40 is free when the subscriber station 12 is newly added to the communication on the bus 40 and attempts to integrate itself into the communication on the bus 40.Upon receiving the respective signals from the bus 40, each transmitting / receiving device 12 generates the corresponding received signal RxD as shown in FIG. 8. The reception signal RxD ideally has no time offset from the transmission signal TxD.As shown in more detail in FIGS. 11 and 12, in the first operating mode (SLOW or SIC) for the transmission signal TxD of FIG. 11, the transmission module 121 generates the signals CAN_H, CAN_L according to FIG. 12 for the bus cores 41, 42 such that a state 403 (sic) additionally exists. State 403 (SIC) may be of different lengths, as shown with state 403_ 0 (sic) in the transition from state 402 (rec) to state 401 (dom) and state 403_ 1 (sic) in the transition from state 401 (dom) to state 402 (rec). State 403_ 0 (sic) is shorter in time than state 403_ 1 (sic). In order to generate signals according to FIG. 12, the transmission module 121 is switched to the first operating mode (SLOW or SIC).Passing through the short sic state 403_ 0 is not required in the ISO / FDIS11898-2:2023, and the state is dependent on the type of implementation. The time duration of the "long" state 403_ 1 (sic) is specified as t_sic< 530ns for the first mode of operation (SLOW or SIC), starting with the rising edge on the transmit signal TxD of FIG. 11.The subscriber station 100 is thus designed like a conventional CAN-XL subscriber station. The user ensures, via the configuration of the data field and / or by selecting the identifiers (ID) of the subscriber stations 100 (commander) and of the subscriber stations 101...10N, that the subscriber station 100 operates as a CAN XL light commander and the subscriber stations 101...10N as a CAN XL light responder according to the polling principle (polling principle). Accordingly, the subscriber station 100 (commander) is allowed to send messages 46 to each of the subscriber stations 101...10N (responder). The subscriber station 100 (commander) encodes in the message whether or not the responder is to respond. Without a prior request, the responder must not send a message.Optionally, however, the subscriber station 100 (commander) can proceed as follows.During operation of the bus system 1, the subscriber station 100 (commander), more precisely the communication control device 11, carries out bus monitoring (bus monitoring). According to ISO 11898-1:2015, the subscriber station 100, in particular the communication control device 11, compares its self-transmitted bits at the sampling point AP (sample point) according to a frame 450, 460 and a transmission signal TxD (FIG. 5 ) with the bits observed on the bus 40 according to the reception signal RxD (FIG. 8 ). A difference is evaluated as an error except for the arbitration and the ACK bit.However, the subscriber station 100 (commander), more precisely the communication control device 11, according to the preset configuration by software, switches off the bus monitoring (bus monitoring) for short bit times t_bt 1, t_bt 2 if the subscriber station 100 (commander) is sender of the message 46. The short bit rates may be in arbitration phase 451 and / or data phase 452. Such short bit times are present at bit rates above 1 Mbit / s, at which the so-called loop delay (loop delay) of the subscriber station 100 (CAN node) comes into the range of a half bit time t_bt 1, t_bt 2 or more. The so-called loop delay specifies the time that passes until the subscriber station 100 can see the bit of the transmission signal TxD transmitted via the terminal TXD internally as the reception signal RxD.In addition, during the operation of bus system 1 with synchronization block 151, subscriber station 100 (commander), more precisely communication control device 11, carries out a synchronization function for all frames 460, which subscriber station 100 (commander) sends to one of responders 101...10N, and in which frames 460 the bits have a bit time t_bt 1, t_bt 2 for bit rates up to 1 Mbit / s.The synchronization block 151 monitors the edges from recessive to dominant or vice versa, i.e. a change between the states 401, 402 or 402, 401 in FIG. 6 or FIG. 7 or FIG. 9 and FIG. 10. The synchronization block 151 synchronizes the position t_A of the sampling point AP (sample point) within a bit time t_bt 1 (FIGS. 9 and 10 ) on the basis of the monitored edges. A receiver thus synchronizes to the transmitter of a frame 450, 460. If an edge ideally occurs at the beginning of a bit time t_bt 1, t_bt 2, no synchronization is necessary, because there are edge changes at the beginning of a bit time. If an edge occurs between the beginning of a bit time t_bt 1, t_bt 2 and the sampling point (sample point), a so-called late edge ("late edge") is present. This causes synchronization in which the current bit time t_bt 1, t_bt 2 is extended. If an edge occurs between the sampling point AP (sample point) and the end of a bit time t_bt 1, t_bt 2, a so-called early edge ("early edge") is present. This causes synchronization in which the current bit time t_bt 1, t_bt 2 is shortened.According to ISO 11898-1:2015, the transmitters of a frame 450, 460 also synchronize themselves. However, the limitation applies that a subscriber station 100 transmitting a dominant bit does not synchronize itself to late edges ("late edges"). This is because the transmitter sees all the self-transmitted bits late ("late") because of the "loop delay". Thus, synchronization to these late edges ("late edges"), which were sent by the subscriber station itself, would lengthen these bits and falsify the bit rate. The allowed synchronization to early edges stabilizes the CAN arbitration at the beginning of frame 450, 460. This is necessary in particular when arbitration takes place.The synchronization function is described in more detail in ISO 11898-1:2015.However, the synchronization function of the synchronization block 151 can be switched with the synchronization module 15, as required, as described below.The evaluation block 153 is configured to evaluate the synchronization configuration bit 1521 in the configuration block 152. The synchronization configuration bit 1521 is set when the subscriber station 100 (commander), more specifically the communication controller 11, is to transmit the frame 460 with a bit time t_bt1 of the first communication phase 451 corresponding to a bit rate greater than a predetermined bit rate. The predetermined bit rate is in particular greater than 1 Mbit / s.If the evaluation of the evaluation block 153 reveals that the synchronization configuration bit 1521 is set, the evaluation block 153 checks whether the subscriber station 100 (commander), more precisely the communication control device 11, is to act (currently) as a transmitter, that is to say is to transmit a frame 460 to a responder on the bus 40. The synchronization configuration bit 1521 is set, for example, along with the bit rate configuration, either by software or hardwired. During operation of bus system 1, configuration bit 1521 is then constant.If the evaluation of the evaluation block 153 reveals that the subscriber station 100 (commander), more precisely the communication control device 11, is to act as a transmitter and is to transmit a frame 460 to the bus 40 to a responder, the evaluation block 151 instructs the switching block 154 to switch off the synchronization block 151. The switching block 154 thus switches off or shuts down the synchronization block 151 and thus its previously described synchronization function for all bits of the frame 460 to be transmitted from the subscriber station 100 as a commander onto the bus 40 up to the last bit of the end field (EOF).The shutdown of the synchronization block 151 prevents the transmitter from synchronizing to its self-transmitted edges that it sees not within the transmitted bit but in one of the subsequent bit times. The synchronization can be switched off because no arbitration can occur because no arbitration is possible any longer at this bit rate t_b1 with more than 1 Mbit / s.After the last bit of the end field (EOF) of the transmitted frame, the switching block 154 of FIG. 4 switches on the synchronization block 151 and thus its synchronization function described above again.Yet, at the subscriber station 100 (commander), the need to send an acknowledgement response (ACK bit or ACK response) for a message 46 of a responder (subscriber station 101...10N) can be deactivated. In addition, the need for receiving an acknowledgement response (ACK bit or ACK response) for a message 46 sent by it to a responder (subscriber station 101...10N) can be deactivated at the subscriber station 100 (commander).According to FIG. 13, the responder subscriber station 101 has, in addition to the communication control device 21 and the transmitting / receiving device 22, a simple control unit (FSM) or optionally a microcontroller 23, to which the communication control device 21 is assigned, and a system ASIC 26 (ASIC= Anwendungs-Specific Integrated Circuit), which can alternatively be a system base chip (SBC), on which a plurality of functions necessary for an electronic module of the subscriber station 101 are combined. The system ASIC 26 has, in particular, an application 261 which can be designed as a computer program (app). One such application is a technical application 261.The application 261 is, for example, a control for a sensor or a transmitter or an actuator or the like, which is controlled by the application 161 (FIG. 4 ) of the commander subscriber station 100 or is intended to supply data for the application 161.The responders have little local computing power, or even none at all, and can perform simple functions, e.g. light diode (LED) on / off, light diode (LED) driving color, as described above. A responder sends a CAN XL frame only if it was requested by the commander by a polling. Thus, upon polling from the commander, the responder CAN subscriber stations (responder) transmit their function information, e.g., a sensor value, etc., to the commander CAN subscriber station (commander) via a CAN XL message.According to FIG. 13, in addition to the transmitting / receiving device 22, an energy supply device 27 is installed in the system ASIC 26, which supplies the transmitting / receiving device 22 with electrical energy. The power supply 27 typically supplies a voltage CAN_Supp of 5 V. However, as necessary, the power supply 27 may supply another voltage having a different value. Additionally or alternatively, the energy supply device 27 can be designed as a current source.The communication control device 21 creates a frame 460 in which bit rate switching or bit rate switching can take place, as described with reference to FIGS. 3 and 4, and / or evaluates such a frame 460 on the basis of the frame 460 received from the commander subscriber station 100. The communication controller 21 acts as a CAN-XL light responder. The devices 21, 22 can only transmit such a frame 460 onto the bus 40 upon request from the commander subscriber station 100 (polling).The transmission module 221 of FIG. 13 is otherwise constructed in the same manner as described above for the transmission module 121 of FIG. 4.The synchronization module 25 of FIG. 13 has a synchronization block 251, a configuration block 252, an evaluation block 253 and a switching block 254. At least one configuration bit 2521, 2522 is stored in the configuration block 252.The synchronization module 25 can also carry out the shutdown of the synchronizations for frames 460 or messages 46 transmitted by the subscriber station 101, as described above with reference to FIG. 4 for the synchronization module 15 for the frames 450, 460. Consequently, the synchronization module 25 always disconnects the synchronization for frames 460 or messages 46 transmitted by the subscriber station 101 at high bit rates. The high bit rates are, for example, greater than 1 Mbit / s.In contrast to the synchronization module 15 of FIG. 4, the synchronization module 25 of FIG. 13 is optionally configured to shut off the synchronization for frames 460 or messages 46 transmitted by the subscriber station 101 in the associated responder, if desired, even at low bit rates. For this purpose, an additional configuration bit 2522 can be set, for example. The low bit rates are, for example, less than or equal to 1 Mbit / s. This shutdown has no great effect on the communication between commander subscriber station 100 and the respective responder subscriber station 101... 10N.As a result, it is possible for the synchronization module 25 of FIG. 13 to be optionally designed to shut down its synchronization function for frames 460 or messages 46 transmitted by the subscriber station 101 both at a low bit rate and at a high bit rate. In other words, it is selectable that the synchronization module 25 of FIG. 13 is designed to switch off its synchronization function for frames 460 or messages 46 transmitted by the subscriber station 101 independently of the bit rate.The subscriber stations 101... 10N can do without these synchronizations because no arbitration takes place in the case of CAN XL light or in the case of communication with the commander subscriber station 100, and no ACK bit is also transmitted at higher bit rates.The synchronization module 25 is otherwise constructed in the same manner as described above for the synchronization module 15.The synchronization modules 15, 25 thus have the effect that communication with CAN XL light is made possible even at bit rates greater than or equal to 1 Mbit / s.The subscriber stations 101... 10N (responders) thus have a CAN-XL light protocol controller. The CAN-XL implementation of the communication control device 21 is adapted for this purpose. The adaptations aim is to simplify or reduce the functionality in order to reduce the resource requirement. For example, the following adaptations are available, among others.The bit monitoring when a message 46 is sent is not present or stopped in the communication control device 21. This is possible because CAN XL light does not require arbitration and cannot transmit error frames either (error frame). The lack of arbitration makes it possible to place the sampling point AP or t_A (sample point) according to FIG. 10 further into the middle of the bit and thus to allow a greater tolerance in the accuracy of the CAN clock. In addition, the function "transmitter delay compensation" can likewise be optimized away, since this is used only for the bit monitoring in the data phase, and the bit monitoring is no longer used.In addition, in the communication control device 21, the signaling by means of error frames (error frames) and overload frames (overload frames) is not present or shut down. This is possible because direct error signaling is not necessary in the case of CAN XL light.In addition, the communication controller 21 does not perform automatic retransmission (re-transmission). Since CAN XL light cannot resolve collisions on bus 40 by arbitration, a CAN XL light subscriber station 101...10N (responder) must not automatically repeat the transmission of a message.Moreover, in the communication controller 21, the fault restriction (fault confinement) is omitted. CAN XL, CAN FD and classic CAN (CC) provide that a subscriber station on the CAN bus is automatically switched off if the subscriber station detects too many communication errors. This serves to prevent a faulty subscriber station from interfering with the communication of other subscriber stations. Since in CAN XL light the responder sends frame 460 only when requested by the commander per frame 460, there is no need for automatic node shut-down.As the communication control device 11 of the commander can also be configured according to the description of FIG. 4, the communication control device 21 of the responder is also configured for high bit rates, namely greater than 1 Mbit / s, in the arbitration phase 451not to transmit an ACK bit if device 21 has correctly received a message 46, andnot to perform synchronization to the seen receive signal RxD (FIG. 8 ) during the transmission of a frame 460.In contrast to the communication control device 11 of the commander, however, the communication control device 21 of the responder is configured to support or to transmit and / or receive only CAN frames in the format XBFF (XL Base Frame Format).Thus, a CAN XL light responder can only send and receive frames in a format (XL), frame 460 of FIG. 3.By limiting to a single frame format, the implementation effort of the CAN XL light responder, in particular its communication control device 21, is significantly reduced.According to a second exemplary embodiment, the communication control devices 11, 21 are set to make no switching of the operating mode of the transceivers 12, 22 between arbitration phase 451 and data phase 452 and back to the arbitration phase. Consequently, the mode switching of the transmitting / receiving devices 12, 22, in particular the switching of their physical layer, is switched off.More specifically, the communication controllers 11, 21 are set to communicate with each other even without switching the bit rate. More specifically, the bit rate of the communication controllers 11, 21 is set as:In the second embodiment, the transmitter carries a frame, whether it be the commander subscriber station 100 or the responder subscriber stations 101... 10N does not perform bit monitoring and resynchronization with the receive signal RxD (FIG. 8 ).Thereby, in the CAN-XL light communication according to the present embodiment, only frames 460 without bit rate switching are used. This saves additional area of responder ASIC 26, and optionally also area of commander ASIC 16, if subscriber station 100 otherwise does not require the bit rate switching function. In addition, clock recovery from the CAN bit stream is facilitated, so that a quartz oscillator in the responder can be saved. This makes it possible to reduce the cost of the responder even further. The saving of a quartz oscillator is also possible in the first exemplary embodiment.In addition, the communication controllers 11, 21 may be set not to perform arbitration in the CAN XL light communication. The subscriber station 100 (commander) controls the communication in such a way that access conflicts to the bus 40 are avoided.In this way, too, a cost-effective connection of responders to CAN bus systems can be effected.The same applies otherwise as described with respect to the first exemplary embodiment.All previously described configurations of the subscriber stations 100, 101... 10N, the bus system 1 and the method carried out therein can be used individually or in all possible combinations. In particular, all features of the above-described exemplary embodiments and / or modifications thereof can be combined as desired. Additionally or alternatively, in particular the following modifications are conceivable.Even if the invention is described above using the example of the CAN bus system, the invention can be used in any communication network and / or communication method in which two different communication phases are used in which the bus states which are generated for the different communication phases can differ.In particular, the bus system 1 according to the exemplary embodiments can be a communication network in which data can be transmitted serially at two different bit rates. In this case, it is to be ensured in the bus system 1 that exclusive, collision-free access of a subscriber station 100, 101... is effected at least for specific periods of time. 10N on a common channel.The number and arrangement of the subscriber stations 100, 101... 10N in the bus system 1 of the exemplary embodiments is arbitrary. It is possible for one or more of the subscriber stations 100 to be present in the bus system 1.It is possible for more than one subscriber station 100 to be present in the bus system 1, to which at least one subscriber station 101...10N is assigned, as described above.In order not to interfere with arbitration between the subscriber stations 100 on the bus 40, messages 46 have from subscriber stations 101... 10N (responder) therefore has an identifier (ID) with a higher priority than the identifier / identifiers (ID) of the subscriber station 100 or of another CAN FD or CAN XL subscriber station.In particular, only one subscriber station 100 (commander) and at least one subscriber station 101...10N (responder) are present.It is conceivable that in subscriber stations 100, module 15 is arranged separately from communication control device 11. It is conceivable that in at least one of the subscriber stations 100, 101...10N, the module 25 is arranged separately from the communication control device 21.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Cited Non-Patent LiteratureISO11898-1:2015 [0003, 0127, 0132]ISO / DIS11898-1:2023 [0004, 0016, 0049, 0050]ISO / DIS11898-2:2023

[0015]

Claims

Responder subscriber station (101; 102;... 101N) for a serial bus system (1), having a communication control device (21) for controlling communication of the subscriber station (101; 102; ... 101N) having a commander subscriber station (100) of the bus system (1) and for evaluating at least one signal (VDIFF received from a bus (40) of the bus system (1); RxD) on the basis of a predetermined frame (460) in which the bit time (t_bt1) in a first communication phase (451) can differ from a bit time (t_bt2) in a second communication phase (452), wherein a field (ADH) can be present in the frame (460) for switching the first bit time (t_bt1) and a first physical layer (451_P) in a first communication phase (451) into a second bit time (t_bt2) and a second physical layer (452_P) in a second communication phase (452), and a synchronization module (25) for synchronizing the communication control device (21) to the signal (VDIFF received from the bus (40); RxD), wherein the synchronization module (25) is configured to disable its synchronization function when the communication control device (21) is to act as a transmitter of the frame (460), so that the responder subscriber station (101; 102;... 101N) is the transmitter of the signal (VDIFF; RxD) received from the bus (40).Responder subscriber station (101; 102;... 101N) according to claim 1, wherein the synchronization module (25) is configured to disable its synchronization function when the bit time (t_bt1) of the first communication phase (451) of the predetermined frame (460) has a predetermined value corresponding to a bit rate greater than a predetermined bit rate, and when the communication control device (21) is to act as transmitter of the frame (460), such that the responder subscriber station (101; 102;... 101N) is the transmitter of the signal (VDIFF; RxD) received from the bus (40).Responder subscriber station (101; 102;... 101N) according to claim 2, wherein the synchronization module (25) comprises a synchronization block (251) configured to synchronize the communication controller (21) with the signal (VDIFF; RxD) received from the bus (40), and a configuration block (252) storing a value for at least one synchronization configuration bit (2521) indicating whether the bit rate is greater than the predetermined bit rate.Responder subscriber station (101; 102;... 101N) according to claim 3, wherein the synchronization module (25) further comprises an evaluation block (253) for evaluating the value of the at least one configuration bit (2521), and a switching block (254) for switching on or off the synchronization of the synchronization block (251) based on the evaluation of the evaluation block (253).Responder subscriber station (101; 102;... 101N) according to any of the preceding claims, wherein the responder subscriber station (101; 102;... 101N) is a subscriber station configured for communication according to CAN XL, wherein the predetermined frame (460) is a CAN XL frame in the XBFF format.Responder subscriber station (101; 102;... 101N) according to any of claims 2 to 5, wherein the predetermined bit rate is 1 Mbit / s.Commander subscriber station (100) for a serial bus system (1), having a communication control device (11) for controlling communication of the subscriber station (100) with a responder subscriber station (101; 102;... 101N) of the bus system (1) and for evaluating at least one signal (VDIFF; RxD) received from a bus (40) of the bus system (1) on the basis of a predetermined frame (450; 460), in which the bit time (t_bt1) in a first communication phase (451) can differ from a bit time (t_bt2) in a second communication phase (452), wherein a field (ADH) can be present in the frame (460) for switching a first physical layer (451_P) in the first communication phase (451) into a second physical layer (452_P) in the second communication phase (452), and a synchronization module (15) for synchronizing the communication control device (11) to the signal (VDIFF) received from the bus (40); RxD), wherein the synchronization module (15) is configured to disable its synchronization function when the bit time (t_bt1) of the first communication phase (451) of the predetermined frame (460) has a predetermined value corresponding to a bit rate greater than a predetermined bit rate, and when the communication control device (11) is to act as transmitter of the predetermined frame (460), so that the commander subscriber station (100) is the transmitter of the signal (VDIFF; RxD) received from the bus (40).Commander subscriber station (100) according to claim 7, wherein the synchronization module (15) comprises a synchronization block (151) configured to synchronize the communication controller (11) with the signal (VDIFF; RxD) received from the bus (40), and a configuration block (152) storing a value for at least one synchronization configuration bit (1521) indicating whether the bit rate is greater than the predetermined bit rate.Commander subscriber station (100) according to claim 8, wherein the synchronization module (15) further comprises an evaluation block (153) for evaluating the value of the at least one configuration bit (1521), and a switching block (154) for switching on or off the synchronization of the synchronization block (151) on the basis of the evaluation of the evaluation block (153).The commander subscriber station (100) according to any of claims 7 to 9, wherein the commander subscriber station (100) is a CAN XL subscriber station, wherein the predetermined frame (460) is a CAN XL frame in the XBFF format.The commander subscriber station (100) according to any of claims 7 to 10, wherein the predetermined bit rate is 1 Mbit / s.Bus system (1), having a bus (40), and at least two subscriber stations (100; 101...10N) which are connected to one another via the bus (40) in such a way that they can communicate with one another in series, and of which one subscriber station is a commander subscriber station (100) according to one of Claims 7 to 11 and at least one subscriber station is a responder subscriber station (101... 101N) according to one of Claims 1 to 6, wherein each of the at least two subscriber stations (100; 101...10N) additionally has a transmitting / receiving device (12; 22) for transmitting a transmission signal (TxD) onto the bus (40) of the bus system (1) and / or for receiving a signal (VDIFF) from the bus (40) of the bus system (1).Bus system (1) according to Claim 12, also having at least one third subscriber station (30) which is designed to transmit and / or receive signals on the basis of a frame (450; 460), wherein the at least one third subscriber station (30) has a communication control device (31) which is designed to negotiate with the commander subscriber station (100) in a first communication phase (451) of the frame (450; 460) whether the third subscriber station (30) or the commander subscriber station (100) has at least temporarily exclusive, collision-free access to the bus (40) in a subsequent second communication phase (452).Method for communication in a serial bus system (1), wherein the method comprises a commander subscriber station (100) according to one of Claims 7 to 11 and a responder subscriber station (101... 101N) according to any one of claims 1 to 6.Method according to claim 14, wherein, in contrast to a CAN XL subscriber station (30), the commander subscriber station (100) and the responder subscriber station (101... 101N) does not perform bit monitoring in sending a message (46), the commander subscriber station (100) does not send an ACK bit if the commander subscriber station (100) has correctly received a message (46), the responder subscriber station (101... 101N) does not transmit an ACK bit when the responder subscriber station (101... 101N) has correctly received a message (46), the responder subscriber station (101... 101N) does not perform error signaling the responder subscriber station (101... 101N) does not use overload frames that responder subscriber station (101... 101N) does not perform automatic retransmission, and the responder subscriber station (101... 101N) does not automatically shut down the responder subscriber station (101... 101N) upon detecting a predetermined number of communication errors.

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