Transmitting / receiving device and communication control device for a user station of a serial bus system and method for communication in a serial bus system

Description

Technical area

[0001] The present invention relates to a transmitting / receiving device and a communication control device for a subscriber station of a serial bus system and a method for communication in a serial bus system that operates with a high data rate and high error robustness. State of the art

[0002] For communication between sensors and control units, for example in vehicles, a bus system is often used in which data is transmitted as messages in the ISO 11898-1:2015 CAN protocol specification using CAN FD. The messages are transmitted as analog signals between the bus system's participants, such as sensors, control units, sensors, etc.

[0003] Each bus device in the bus system is connected to the bus via a transceiver. The transceiver contains at least one receive comparator, which receives the analog signals from the bus and converts them into a digital signal. The content of the digital signal can be interpreted by a communications control device using its protocol controller. Furthermore, the communications control device can create a signal for transmission on the bus and send it to the bus via the transceiver. This allows information to be exchanged between the bus devices.

[0004] In order to be able to transmit data over the bus at a higher bit rate than with CAN, an option for switching to a higher bit rate within a message was created in the CAN FD message format and the CAN XL message format. With such technologies, the maximum possible data rate is increased by using a higher clock frequency in the data fields compared to CAN. For CAN FD frames or CAN FD messages, the maximum possible data rate is increased beyond a value of 1 Mbit / s. In addition, the payload length has been extended from 8 to up to 64 bytes. The same applies to CAN XL, where the data transmission speed is to be increased to the range of, for example, 10 BaseT1-S Ethernet and the payload length of up to 64 bytes previously achieved with CAN FD is to be increased. This advantageously maintains the robustness of the CAN or CAN FD-based communication network.

[0005] For transmission at the higher bit rate, the previous operating mode of the transceiver must be switched from one operating mode for transmission at the lower bit rate (Z_SL operating mode) to another operating mode. It should be noted that during transmission at the higher bit rate, only one of the subscriber stations in the bus system is the sender of the message, whereas all other subscriber stations are only the receiver of the message. Therefore, when signaling the operating mode (Z_F) for the higher bit rate, a distinction is made between whether the subscriber station is only a receiver (Z_F_RX operating mode) or also a transmitter (Z_F_TX operating mode), in order to switch the operating mode of its transceiver accordingly.

[0006] It is conceivable that the communication control device signals the transmitting / receiving device to which operating mode the transmitting / receiving device is to be switched. However, this leaves the communication control device with no way of knowing whether the transmitting / receiving device even receives the signal for the switching of operating mode and whether the transmitting / receiving device correctly interprets or implements the signal for the switching of operating mode.

[0007] EP 2 800 316 A1 relates to a bus system in which communication takes place according to CAN FD with devices and a method according to the preambles of claims 1, 13 and 15. Disclosure of the invention

[0008] Therefore, it is an object of the present invention to provide a transmitting / receiving device and a communication control device for a subscriber station of a serial bus system, as well as a method for communication in a serial bus system, which solve the aforementioned problems. In particular, a transmitting / receiving device and a communication control device for a subscriber station of a serial bus system, as well as a method for communication in a serial bus system, are to be provided in which the switching of the operating mode of the transmitting / receiving device can be carried out with high robustness and the implementation can be verified inexpensively in terms of time and cost.

[0009] The object is achieved by a transmitting / receiving device for a subscriber station of a serial bus system having the features of claim 1. The transmitting / receiving device has a first connection for receiving a transmit signal from a communication control device, a transmitting module for transmitting the transmit signal to a bus of the bus system, in which bus system at least a first communication phase and a second communication phase are used for exchanging messages between subscriber stations of the bus system, a receiving module for receiving the signal from the bus, wherein the receiving module is designed to generate a digital receive signal from the signal received from the bus, a second connection for transmitting the digital receive signal to the communication control device and for receiving an operating mode switching signal from the communication control device,and a switching feedback block for outputting a feedback signal about a switching of the operating mode due to the operating mode switching signal, wherein the switching feedback block is connected to the first terminal for outputting the feedback signal via the first terminal to the communication control device as described in claim 1.

[0010] The transmitting / receiving device can provide feedback to the communication control device via the existing first connection in the transmit signal, indicating whether the transmitting / receiving device has received the signal indicating the operating mode switch and how the signal was interpreted. Based on this information, the communication control device can check whether the transmitting / receiving device is correctly switched for the current operating state or the current communication phase. This makes it possible to verify the operating mode switch of the transmitting / receiving device, which increases the robustness of the bus system. The reason for this is that the communication control device can react specifically in the event of an error because it is aware of the problem.

[0011] A high level of robustness of the feedback is also ensured by the fact that the communication control unit of the transmitting / receiving device signals that a mode change is to be performed via the second port in the received signal, rather than via the first port. Thus, the signaling of the mode change and the signaling of the feedback as to whether the mode change has been performed are carried out via two different channels or transmission paths.

[0012] As a result, no additional connector or protocol controller is required in the transceiver device. All of this significantly saves silicon area and thus resources, space, and costs.

[0013] The feedback of the operating mode switch to the communication control device also enables the communication control device to react accordingly in the event of an error. For example, the communication control device can send an error frame to abort the transmission of the frame. This allows transmission with incorrectly configured bus components to be aborted as quickly as possible. This increases the net data rate that can be transmitted in the bus system. This makes communication within the bus system more robust.

[0014] The feedback of the operating mode switch to the communication control device aids in troubleshooting, as the communication control device knows whether the transmitting / receiving device was able to change state. The communication control device can also indicate via software that the connected communication control device has already failed to switch mode K times, where K is a natural number, including 0. The value of K can be interpreted as an indication of how soon the transmitting / receiving device might fail. To prevent failure, the transmitting / receiving device can then be replaced in a workshop in good time before the failure occurs. This increases the reliability of the system in which the bus system is used.

[0015] Furthermore, the transmit / receive device can maintain CAN arbitration in one of the communication phases while still significantly increasing the transmission rate compared to CAN or CAN FD. This can be achieved by using two communication phases with different bit rates and reliably identifying and verifying the start of the second communication phase, in which the payload data is transmitted at a higher bit rate than in the arbitration, for the transmit / receive device. As a result, a significant increase in the bit rate and thus the transmission speed from transmitter to receiver is achievable. At the same time, high error robustness is ensured.

[0016] The method performed by the transmitting / receiving device can also be used if the bus system also includes at least one CAN subscriber station and / or at least one CAN FD subscriber station that sends messages according to the CAN protocol and / or CAN FD protocol.

[0017] Advantageous further embodiments of the transmitting / receiving device are specified in the dependent claims.

[0018] The switching feedback block can have an operating mode detection module for detecting from the output signals of the transmitting module and the receiving module which operating mode the transmitting module and the receiving module are switched to, and an operating mode feedback module for evaluating an operating mode status signal output by the operating mode detection module, wherein the operating mode feedback module can be designed to decide with a result of the evaluation whether the operating mode feedback module must provide feedback to the communication control device via the digital transmit signal and when the feedback must be sent.

[0019] According to a specific embodiment, the operating mode feedback module can be designed to insert the feedback into the digital transmission signal after the switching of the operating mode that was signaled with the operating mode switching signal.

[0020] According to another specific embodiment, the operating mode feedback module may be configured to insert the feedback into the digital receive signal after the operating mode switching signal, but before the switching of the operating mode that was signaled with the operating mode switching signal.

[0021] According to one embodiment, the operating mode feedback module is designed to drive the feedback more strongly at the beginning than at the end of the feedback.

[0022] It is conceivable that the operating mode feedback module is designed to insert the feedback into the digital transmission signal as at least one pulse with a value that is inverse to a value of the digital transmission signal.

[0023] In this case, the at least one pulse can last on the bus until a subsequent edge change that follows in the digital receive signal.

[0024] The transmitting / receiving device may further comprise an operating mode switching block connected to the second terminal in order to evaluate the operating mode switching signal received at the second terminal from the communication control device, wherein the operating mode switching block is designed to switch the transmitting module and / or the receiving module into one of at least three different operating modes depending on a result of the evaluation.

[0025] The operating mode switching signal received at the second terminal from the communication control device may be at least one pulse having a value that is inverse to a value of the digital received signal, wherein the operating mode switching block is configured to switch the receiving module from the first operating mode to the second operating mode if the switching signal has one pulse, wherein the operating mode switching block is configured to switch the transmitting module and the receiving module from the first operating mode to the third operating mode if the switching signal has two pulses. It is conceivable that the transmitting / receiving device in the second operating mode is not the sender of the message in the second communication phase, and that the transmitting / receiving device in the third operating mode is the sender of the message in the second communication phase.

[0026] According to a special embodiment, the transmitting / receiving device is designed to transmit at least one pulse as feedback via the first terminal, which pulse differs from the at least one pulse of the operating mode switching signal at the second terminal in polarity and / or number of pulses.

[0027] The aforementioned object is also achieved by a communication control device for a subscriber station of a serial bus system with the features of claim 13. The communication control device has a communication control module for generating a transmission signal for controlling communication of the subscriber station with at least one other subscriber station of the bus system, in which bus system at least a first communication phase and a second communication phase are used for exchanging messages between subscriber stations of the bus system, a first connection for transmitting the transmission signal to a transmitting / receiving device which is designed to transmit the transmission signal to a bus of the bus system, a second connection for receiving a digital reception signal from the transmitting / receiving device, wherein the communication control device is designed to generate an additional signal,which indicates to the transmitting / receiving device that a switch from the current operating mode to another of at least three different operating modes is to be made, and which implements internal communication between the communication control module and the transmitting / receiving device, and wherein the communication control module is configured to send the additional signal to the transmitting / receiving device via the second connection in the digital received signal, and wherein the communication control module is configured to receive, via the first connection in the transmitted signal, a feedback signal from the transmitting / receiving device regarding a successful switch in the operating mode due to the operating mode switch signal and to evaluate the feedback signal, as described in claim 13.

[0028] The communication control device offers the same advantages as previously mentioned with regard to the transmitting / receiving device.

[0029] The transmitting module may be configured to drive signal bits onto the bus in the first communication phase with a first bit time that is at least 10 times greater than a second bit time of bits that the transmitting module drives onto the bus in the second communication phase. The operating mode switching signal, via the second terminal, may have at least one pulse with a duration that is shorter than the first bit time and longer than the second bit time, or at least one pulse with a pulse duration that is approximately equal to or shorter than the second bit time, to signal that the operating mode is to be switched.In addition, the feedback via the first terminal for signaling that the operating mode has been switched can have at least one pulse with a time duration that is less than the first bit time and greater than the second bit time, or at least one pulse with a pulse time duration that is approximately equal to the second bit time or less than the second bit time.

[0030] According to one option, the signal received from the bus in the first communication phase is generated with a different physical layer than the signal received from the bus in the second communication phase.

[0031] It is conceivable that in the first communication phase it is negotiated which of the participant stations of the bus system will receive at least temporarily exclusive, collision-free access to the bus in the subsequent second communication phase.

[0032] The previously described transmitting / receiving device and the previously described communication control device can be part of a subscriber station of a bus system, which also comprises a bus and at least two subscriber stations connected to one another via the bus in such a way that they can communicate with one another serially. At least one of the at least two subscriber stations has a previously described transmitting / receiving device and a previously described communication control device.

[0033] The aforementioned object is also achieved by a method for communication in a serial bus system according to claim 15. The method is carried out with a transmitting / receiving device of a subscriber station for a bus system, in which at least a first communication phase and a second communication phase are used to exchange messages between subscriber stations of the bus system, wherein the subscriber station has a transmitting module, a receiving module, an operating mode switching block, a switching feedback block, a first terminal, and a second terminal, and wherein the method comprises the steps of receiving, with the receiving module, a signal from the bus of the bus system, generating, with the receiving module, a digital received signal from the signal received from the bus, and outputting the digital received signal at the second terminal, receiving, with the operating mode switching block connected to the second terminal,the mode switching signal at the second terminal from the communication control device to evaluate the received mode switching signal for a mode switching, and outputting, with the switching feedback block connected to the first terminal, a feedback signal about a completed mode switching due to the mode switching signal via the first terminal to the communication control device, as described in claim 15.

[0034] The method offers the same advantages as previously mentioned with respect to the transmitting / receiving device and / or the communication control device.

[0035] Further possible implementations of the invention also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. 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. Drawings

[0036] The invention is described in more detail below with reference to the accompanying drawings and exemplary embodiments. They show: Fig. 1 a simplified block diagram of a bus system according to a first embodiment; Fig. 2 a diagram illustrating the structure of messages that can be sent by subscriber stations of the bus system according to the first embodiment; Fig. 3 a simplified schematic block diagram of a subscriber station of the bus system according to the first embodiment; Fig. 4 bis Fig. 6 an example of signals in the first embodiment relating to a feedback of an operating mode switch of the transmitting / receiving device in a subscriber station acting as a transmitter in a second communication phase (data phase); and Fig. 7 bis Fig. 9 an example of signals in the first embodiment with respect to a feedback of an operating mode switchover of the transmitting / receiving device in a subscriber station which acts only as a receiver in a second communication phase (data phase).

[0037] In the figures, identical or functionally equivalent elements are provided with the same reference numerals unless otherwise indicated. Description of the embodiments

[0038] Fig. 1 shows, as an example, a bus system 1, which is fundamentally designed, in particular, for a CAN bus system, a CAN FD bus system, a CAN FD successor 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.

[0039] In Fig. 1 The bus system 1 has a plurality of subscriber stations 10, 20, 30, each connected to a bus 40 with a first bus wire 41 and a second bus wire 42. The bus wires 41, 42 can also be called CAN_H and CAN_L and are used for electrical signal transmission after coupling in the dominant levels or generating recessive levels for a signal in the transmit state. Messages 45, 46 in the form of signals can be transmitted serially between the individual subscriber stations 10, 20, 30 via the bus 40. The subscriber stations 10, 20, 30 are, for example, control units, sensors, display devices, etc. of a motor vehicle.

[0040] As in Fig. 1 As shown, the subscriber station 10 has a communication control device 11, a transmitting / receiving device 12 and a switching feedback block 15. The subscriber station 20, on the other hand, has a communication control device 21 and a transmitting / receiving device 22. The subscriber station 30 has a communication control device 31, a transmitting / receiving device 32 and a switching feedback block 35. The transmitting / receiving devices 12, 22, 32 of the subscriber stations 10, 20, 30 are each directly connected to the bus 40, even if this is not the case in Fig. 1 is not illustrated.

[0041] In each subscriber station 10, 20, 30, the messages 45, 46 are exchanged bit-by-bit in the form of frames via a TXD line and an RXD line between the respective communication control device 11, 21, 31 and the associated transmit / receive devices 12, 22, 32. This is described in more detail below.

[0042] The communication control devices 11, 21, 31 each serve to control 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 that are connected to the bus 40.

[0043] The communication control devices 11, 31 create and read first messages 45, which are, for example, modified CAN messages 45, which are also referred to below as CAN XL messages 45. The modified CAN messages 45 or CAN XL messages 45 are constructed on the basis of a CAN FD successor format, which is Fig. 2 described in more detail. The communication control devices 11, 31 can also be configured to provide a CAN XL message 45 or a CAN FD message 46 to the transmitting / receiving devices 12, 32 or to receive one from them as needed. The communication control devices 11, 31 thus create and read a first message 45 or a second message 46, wherein the first and second messages 45, 46 differ in their data transmission standard, namely CAN XL or CAN FD in this case.

[0044] The communication control device 21 can be designed like a conventional CAN protocol controller or CAN controller according to ISO 11898-1:2015, in particular like a CAN FD-tolerant Classical CAN controller or a CAN FD controller. The communication control device 21 creates and reads second messages 46, for example Classical CAN messages or CAN FD messages 46. The CAN FD messages 46 can contain from 0 to 64 data bytes, which are also transmitted at a significantly faster data rate than a Classical CAN message. In the latter case, the communication control device 21 is designed like a conventional CAN FD controller.

[0045] The transmitting / receiving devices 12, 32 can be designed as CAN XL transceivers, except for the differences described in more detail below. The transmitting / receiving devices 12, 32 can additionally or alternatively be designed as a conventional CAN FD transceiver. The transmitting / receiving device 22 can be designed as a conventional CAN transceiver or CAN FD transceiver.

[0046] With the two subscriber stations 10, 30, the formation and then transmission of messages 45 with the CAN XL format as well as the reception of such messages 45 is possible.

[0047] Fig. 2 shows a CAN XL frame 450 for message 45, as sent by the transmitting / receiving device 12 or the transmitting / receiving device 32. The CAN XL frame 450 is divided into different communication phases 451 to 455 for CAN communication on the bus 40, namely an arbitration phase 451, a first switching phase 452, which is located at the end of the arbitration phase 451, a data phase 453, a second switching phase 454, which is located at the end of the data phase 453, and a frame end phase 455.

[0048] In the arbitration phase 451, for example, a bit is sent at the beginning, also called the SOF bit, which indicates the start of the frame or start of frame. In the arbitration phase 451, an identifier with, for example, 11 bits is also sent to identify the sender of message 45. During arbitration, the identifier is used to negotiate bit by bit between the subscriber stations 10, 20, 30 which subscriber station 10, 20, 30 wishes to send message 45, 46 with the highest priority and will therefore receive exclusive access to bus 40 of bus system 1 for the next transmission time in the switchover phase 452 and the subsequent data phase 453.

[0049] In the first switching phase 452, in the present embodiment, the switchover from the arbitration phase 451 to the data phase 453 is prepared. The switching phase 452 can have a bit AL1 that has the bit duration T_B1 of a bit of the arbitration phase 451 and is transmitted with the physical layer of the arbitration phase 451. The physical layer corresponds to the physical layer or layer 1 of the well-known OSI model (Open Systems Interconnection Model).

[0050] In the data phase 453, after a DH1 bit and a DL1 bit, an 8-bit data field identifier can be sent, for example. This identifies the type of content in the data field. For example, the data field identifier can contain the value 9, which indicates that the data field contains a data packet structured according to Internet Protocol Version 4 (IPv4). Following the data field identifier, an 11-bit data length code can be sent, which can then assume values ​​from 1 to 2048, for example, or another value with a step size of 1. The data length code can alternatively comprise fewer or more bits, so that the value range and the step size can assume different values. This is followed by further fields, such as the header checksum field. The payload of the CAN XL frame 450 orof message 45, which can also be referred to as the data field of message 45. The payload can contain data corresponding to the value range of the data length code, for example, with a number of up to 2048 bytes or a larger number of bytes, or any other arbitrary number of data. At the end of data phase 453, for example, a checksum field can contain a checksum of the data of data phase 453 and the data of arbitration phase 451. The sender of message 45 can insert stuff bits into the data stream as an inverse bit after every predetermined number of identical bits, in particular 10 identical bits. In particular, the checksum is a frame checksum F_CRC, with which all bits of frame 450 up to the checksum field are secured. This can be followed by an FCP field with a predetermined value, for example 1100.

[0051] In the second switching phase 454, in the present embodiment, the switchover from the data phase 453 to the frame end phase 455 is prepared. Protocol format information contained in at least one bit is transmitted, which is suitable for implementing the switchover. The switching phase 454 can have a bit AH1, which has the bit duration T_B1 of a bit of the arbitration phase 451, but is transmitted with the physical layer of the data phase 453.

[0052] In the frame end phase 455, at least one acknowledge bit ACK can be included after two bits AL2, AH2 in an end field in the frame end phase 455. This can be followed by a sequence of seven identical bits, indicating the end of the CAN XL frame 450. The at least one acknowledge bit ACK can be used to indicate whether or not a receiver has detected an error in the received CAN XL frame 450 or message 45.

[0053] At least in the arbitration phase 451 and the frame end phase 455, a physical layer similar to CAN and CAN-FD is used. In addition, in the first switchover phase 452, at least partially, i.e., at the beginning, a physical layer similar to CAN and CAN-FD can be used. In addition, in the second switchover phase 454, at least partially, i.e., at the end, a physical layer similar to CAN and CAN-FD can be used.

[0054] An important point during phases 451, 455, at the beginning of phase 452, and at the end of phase 454 is the use of the well-known CSMA / CR method, which allows simultaneous access of subscriber stations 10, 20, 30 to bus 40 without destroying the higher-priority message 45, 46. This allows additional bus subscriber stations 10, 20, 30 to be added to bus system 1 relatively easily, which is very advantageous.

[0055] The CSMA / CR method results in so-called recessive states on the bus 40, which can be overwritten by other subscriber stations 10, 20, 30 with dominant states on the bus 40.

[0056] The arbitration at the beginning of a frame 450 or the message 45, 46 and the acknowledgment in the frame end phase 455 of the frame 450 or the message 45, 46 is only possible if the bit time is significantly more than twice as long as the signal propagation time between any two subscriber stations 10, 20, 30 of the bus system 1. Therefore, the bit rate in the arbitration phase 451, the frame end phase 455 and at least partially in the switching phases 452, 454 is selected to be slower than in the data phase 453 of the frame 450. In particular, the bit rate in phases 451, 452, 454, 455 is selected to be 500 kbit / s, which results in a bit time of approximately 2 µs, whereas the bit rate in the data phase 453 is selected to be 5 to 10 Mbit / s. or more is selected, resulting in a bit time of approximately 0.1 µs or shorter. Thus, the bit time of the signal in the other communication phases 451, 452, 454, 455 is at least a factor of 10 longer than the bit time of the signal in the data phase 453.

[0057] A sender of message 45, for example, subscriber station 10, begins sending bits of the switching phase 452 and the subsequent data phase 453 to bus 40 only when subscriber station 10 as the sender has won the arbitration and subscriber station 10 as the sender thus has exclusive access to bus 40 of bus system 1 for sending. The sender can either switch to the faster bit rate and / or the other physical layer after part of the switching phase 452 or only switch to the faster bit rate and / or the other physical layer with the first bit, i.e. with the beginning of the subsequent data phase 453.

[0058] In general, the following different properties can be realized in the bus system with CAN XL compared to CAN or CAN FD: a) Adoption and, if necessary, adaptation of proven properties that are responsible for the robustness and user-friendliness of CAN and CAN FD, in particular frame structure with identifier and arbitration according to the CSMA / CR procedure, b) Increasing the net data transmission rate to approximately 10 megabits per second, and c) Increasing the size of the payload data per frame to a maximum of 2 kbytes or to any other value.

[0059] Fig. 3 shows the basic structure of the subscriber station 10 with the communication control device 11, the transmitting / receiving device 12 and the switching feedback block 15. The subscriber station 30 is constructed in a similar way as in Fig. 3 shown, except that block 35 is provided separately from the communication control device 31 and the transceiver 32. Therefore, the subscriber station 30 and block 35 are not described separately. The functions of the switching feedback block 15 described below are identical in the switching feedback block 35.

[0060] According to Fig. 3 The communication control device 11 also has a communication control module 111, a transmission signal output driver 112, an RxD port configuration module 113, and a TxD port configuration module 114. The communication control device 11 is configured as a microcontroller or comprises a microcontroller. The communication control device 11 processes signals from any application, for example, a control unit for an engine, a safety system for a machine or vehicle, or other applications. The communication control module 111 is a protocol controller that creates and / or evaluates the TxD and RxD signals according to a predetermined communication protocol, such as CAN FD or CAN XL in this case.

[0061] Not shown in Fig. 3 However, it is a system ASIC (ASIC = Application-Specific Integrated Circuit), which can alternatively be a system base chip (SBC) on which several functions necessary for an electronic module of the subscriber station 10 are combined. Among other things, the transmitting / receiving device 12 and a power supply device (not shown) that supplies the transmitting / receiving device 12 with electrical energy can be incorporated into the system ASIC. The power supply device typically supplies a CAN_Supply voltage of 5 V. However, depending on requirements, the power supply device can supply a different voltage with a different value and / or be configured as a current source.

[0062] According to Fig. 3 The transmitting / receiving device 12 also has a transmitting module 121, a receiving module 122, a driver 123 for the transmitting signal TxD, a receiving signal output driver 124, a driver 125 which outputs a signal RxD_TC to the switching block 126, and a switching block 126. The switching block 126 forms an operating state switching signal S_OP for switching the transmitting module 121 from the signal RxD_TC and a signal S_SW, which is the output signal of the receiving module 122. In addition, the switching block 126 forms an operating state switching signal S_OPT for switching reception thresholds of the receiving module 122 from the signal RxD_TC and the signal S_SW. The switching block 126 detects that a signal from the communication control module 111 is present by the Switching block 126 compares the signal RxD_TC and the signal S_SW, because the signal RxD_TC contains at least one pulse AH_1, AH_2 sent by the communication control module 111. This is with respect to Fig. 4 bis Fig. 9 described in more detail below

[0063] The use of the TxD signal in the switching block 126 is optional, as in Fig. 3 shown by the dashed line on the TxD signal. The RxD signal and the RxD_TC signal have the same waveform, with the two signals separated by a driver 125.

[0064] The transmitting module 121 is also called the transmitter. The receiving module 122 is also called the receiver.

[0065] The switching block 126 can be designed as a switching block which in particular has at least one flip-flop.

[0066] The switching feedback block 15 has an operating mode detection module 151 and an operating mode feedback module 152, the functions of which are described in more detail below.

[0067] Although the following always refers to the transmitting / receiving device 12, it is alternatively possible to provide the receiving module 122 in a separate device external to the transmitting module 121. The transmitting module 121 and the receiving module 122 can be constructed as in a conventional transmitting / receiving device 22. The transmitting module 121 can, in particular, have at least one operational amplifier and / or one transistor. The receiving module 122 can, in particular, have at least one operational amplifier and / or one transistor.

[0068] As in Fig. 3 As shown, 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 first and second bus wires 41, 42 are connected to the transmitting module 121 and the receiving module 122 in the transmitting / receiving device 12. The voltage supply for the power supply device for supplying the first and second bus wires 41, 42 with electrical energy is implemented as usual. Furthermore, the connection to ground or CAN_GND is implemented as usual. The same applies to the termination of the first and second bus wires 41, 42 with a terminating resistor.

[0069] During operation of the bus system 1, when the subscriber station 10 acts as a transmitter, the transmitting module 121 converts a transmit signal TxD of the communication control device 11 into corresponding signals CAN_H and CAN_L for the bus wires 41, 42 and transmits these signals CAN_H and CAN_L to the bus 40. Even if the signals CAN_H and CAN_L are mentioned here for the transmitting / receiving device 12, these are to be understood as signals CAN-XL_H and CAN-XL_L with regard to the message 45, which in the data phase 453 differ from the conventional signals CAN_H and CAN_L in at least one feature, in particular with regard to the formation of the bus states for the various data states of the signal TxD and / or with regard to the voltage or the physical layer and / or the bit rate.

[0070] As a result of the signals on bus 40, a differential signal VDIFF = CAN_H - CAN_L is formed. With the exception of an idle or standby state, the transmitting / receiving device 12 with the receiving module 122 always listens for a transmission of data or messages 45, 46 on bus 40 during normal operation, regardless of whether the subscriber station 10 is the sender of the message 45 or not. The receiving module 122 forms a signal S_SW and forwards it via the received signal output driver 124 as a digital received signal RxD to the communication control device 11, as shown in Fig. 3 shown.

[0071] At the end of the arbitration phase 451, it is clear which of the subscriber stations 10, 30 will act as the sender and which will act only as the receiver in the subsequent data phase 453. In the present example, subscriber station 10 acts as both the sender and the receiver, while subscriber station 30 acts only as the receiver. Of course, however, subscriber station 30 can alternatively be the sender.

[0072] The switching block 126 is configured to detect the beginning of the respective switching phases 452, 454 in a received message 45 from the bus 40 and then, depending on the function of the subscriber station 10 in the subsequent communication phase, to switch the properties of the transmitting / receiving device 12. The switching block 126 can switch between the following operating modes of the transmitting / receiving device 12: a) first operating mode: Z_SL = transmit / receive characteristics for the arbitration phase 451, transmit module 121 in the transmit / receive device 12 generates dominant and recessive states on the bus 40, receive module 122 operates with a receive threshold T_a of typically about 0.7 V. In addition, the receive module 122 can operate with a negative receive threshold, in particular for integrating the subscriber station 10 into an ongoing communication on the bus 40. c) second operating mode: transmit / receive properties for the data phase 453 as a receiver (receiving node), transmit module 121 in the transmit / receive device 12 generates recessive states or is optionally switched off after the switching phase 452, since the transmit / receive device 12 is not a transmitter but only acts as a receiver of the message 45 or a frame 450, receive module 122 operates with a receive threshold T_d of typically approximately 0.0 V.c) third operating mode: transmit / receive characteristics for the data phase 453 as a transmitter (transmitting node), transmitting module 121 in the transmitting / receiving device 12 drives a 0-state or a 1-state depending on the TxD signal, since the transmitting / receiving device 12 acts as a transmitter of the message 45 or a frame 450, receiving module 122 operates with a receiving threshold T_d of typically about 0.0 V.

[0073] The RxD port configuration module 113 of the communication controller 11 configures the RxD port depending on the required communication direction using signals S1, S2 at the input of the module 113, as described below. The S1 signal can be referred to as RxD_out_ena, which enables no driving of the additional RxD_TC signal via the RxD port (first port mode) or driving of the additional RxD_TC signal via the RxD port (second port mode). The S2 signal can be referred to as RxD_out_val.Depending on the value of signal S2, communication control device 11 drives the RxD port at the switching times between the two different communication phases to signal the operating mode to be set to the transmitting / receiving device 12, i.e., firstly, in the first switching phase 452 to switch between the arbitration phase 451 and the data phase 453, and secondly, in the second switching phase 454 to switch between the data phase 453 and the frame end phase 455. Optionally, depending on the value of signal S2, communication control device 11 can drive the RxD port in a third connection operating mode, which can also be called "talk mode," in which internal communication between devices 11, 12 is possible.Otherwise, as is common especially with CAN, the RxD port is an input for the communication control device 11, i.e., not an output as previously described, so that the communication control device 11 does not drive the RxD port. The RxD port can thus be operated bidirectionally using the RxD port configuration module 113 and the signals S1, S2. In other words, the RxD port is a bidirectional port.

[0074] For this purpose, the communication control device 11 and the output driver 124 are configured such that the communication control device 11 drives the RxD terminal more strongly than the output driver 124 when driving for the purpose of signaling the operating mode to be activated. This prevents the value of the RxD line from being indeterminate if both the communication control device 11 and the output driver 124 drive the RxD terminal, resulting in an overlap of the two signal sources at the RxD terminal. With such an overlap of the two signal sources at the RxD terminal, the communication control device 11 always prevails. As a result, the value of the RxD line is always determined.

[0075] The TxD port configuration module 114 of the communication controller 11 configures the TxD port depending on the required communication direction using signals S3, S4 at the input of the module 114, as described below. The S3 signal can be referred to as TxD_out_ena, which enables no driving of the additional TxD_PC signal via the TxD port (first port mode) or driving of the additional TxD_PC signal via the TxD port (second port mode). The S4 signal can be referred to as TxD_out_val. Depending on the value of the S4 signal, the communication controller 11 does not drive the TxD port at the switching times between the two different communication phases in order to receive a response R_S from the transceiver 12, more precisely its block 15.The feedback R_S signals to the communication control device 11 whether the transmitting / receiving device 12 was switched to the correct operating mode in the respective switching phases 452, 454.

[0076] Here, the communication control device 11 and the module 152 are designed such that the transmitting / receiving device 12 drives the TxD terminal more strongly than the driver 112 when driving for the purpose of feedback R_S of the switched-on operating mode. As a result, the value of the TxD line is always determined, as previously described for the RxD line.

[0077] In particular, the at least one pulse sent from the transmitting / receiving device 12 to the communication control device 11 can be driven strongly at the TxD terminal or on the TxD line to provide feedback on the operating mode of the transmitting / receiving device 12. Subsequently, the transmitting / receiving device 12 can transition to a weaker mode for the feedback until the end of the feedback, in particular within one bit time of the transmitted signal TxD, so that the level driven by the communication control device 11 can be exceeded.

[0078] Thus, a time-dependent driver power is used in the transmitting / receiving device 12 and / or the communication control device 11.

[0079] Thus, the switching block 126 can provide the option of setting one of the aforementioned at least three operating modes in the transmitting / receiving device 12, which are signaled via the RxD connection. Furthermore, the feedback signal R_S of the switching can be provided via the TxD line. An additional connection in the form of another pin on the transmitting / receiving device 12 and thus also on the communication control device 11 is not required for these two signaling modes.

[0080] The switching block 126 is designed for this purpose Fig. 3 provided with at least two inputs, via which a signal RxD_TC, the signal S_SW and optionally the signal TxD are fed into the switching block 126. The signal RxD_TC is based on a signal that is sent from the communication control device 11 via the connection for the RxD signal to the transmitting / receiving device 12. With the signal RxD_TC, the communication control device 11 signals to the transmitting / receiving device 12 at least that the transmitting / receiving device 12 must now switch to the corresponding operating mode for the data phase 453. In addition, the communication control device 11 signals to the transmitting / receiving device 12 with the signal RxD_TC and / or the signal TxD which of the operating modes Z_F_RX, Z_F_TX the switchover should be made to. This is particularly helpful when switching from the arbitration phase 451 to the data phase 453.At the end of the data phase 453, the communication control device 11 can use the RxD_TC signal to signal the switchover of the transmitting / receiving device 12 from either of the two operating modes of the data phase 453 to the Z_SL operating mode for the arbitration phase 451. Furthermore, the RxD_TC signal can be used to send any other information from the communication control device 11 to the transmitting / receiving device 12, as previously mentioned.

[0081] According to Fig. 3 The transceiver 12 routes the RxD_TC signal from the RxD terminal via the driver 125 to the RxD_TC signal terminal 126. The S_SW signal, on the other hand, is generated from the signal received from the bus 40. The RxD_TC signal is routed between the RxD signal terminal and the output of the receive signal driver 124 to the switch block 126. The S_SW signal is routed from the output of the receive module 122 and before the input of the receive signal driver 124 to the switch block 126.

[0082] If the switching block 126 detects the switching phase 452, the operating state of the transmitting module 121 and / or the receiving module 122 and thus the operating mode of the transmitting / receiving device 12 is switched using the signals S_OP, S_OPT output from the switching block 126.

[0083] In the switching feedback block 15, the operating mode detection module 151 determines from the output signals of the transmitting module 121 and the receiving module 122 which operating mode Z_SL, Z_F_RX, Z_F_ZX the transmitting module 121 and the receiving module 122 are switched to. In particular, the operating mode detection module 151 is designed as a comparator. The operating mode detection module 151 forwards the detection result as a status signal S_E to the operating mode feedback module 152. Using the status signal S_E, the operating mode feedback module 152 decides whether the operating mode feedback module 152 must send a feedback signal R_S to the communication control device 11 via the TxD signal, and how, i.e., in what form and when, the feedback signal R_S must be sent.

[0084] Optionally, the operating mode feedback module 152 can additionally use a status signal S_B from the operating mode switching block 126, which is configured to execute the switching of the Z_SL, Z_F_RX, Z_F_ZX operating mode based on the RxD_TC operating mode switching signal. The status signal S_B indicates whether a signaling of the switching condition has been detected. Optionally, the status signal S_B also indicates the operating mode to be switched to.

[0085] If the feedback R_S is positive, i.e. the transmitting / receiving device 12 has recognized the signaling and has switched the operating mode as requested, then the operating mode feedback module 152 sends a signal TxD_PC for the communication control device 11 to the TxD connection in order to provide the feedback R_S for the communication control device 11 via the TxD connection.

[0086] The transmitting / receiving devices 12, 32 have various options for providing feedback via TxD signal. This is with respect to Fig. 4 bis Fig. 9 This is described in more detail below using an example. It is assumed that subscriber station 10 acts as a transmitter (transmitting node) for data phase 453 and subscriber station 30 acts only as a receiver (receiving node) for data phase 453.

[0087] Fig. 4 bis Fig. 6 show an example of signals before, during, and after the switching phase 452, and subsequently before, during, and after the switching phase 454 at subscriber station 10 (transmitting node). At the transition from the arbitration phase 451 to the data phase 453, the switching phase 452 switches from a bit duration T_B1 of the arbitration phase 451 to a smaller or shorter bit duration T_B2 of the data phase 453 and to another physical layer. In doing so, the operating mode Z_SL of the transmitting / receiving device 12 is switched to the operating mode Z_F_TX of the transmitting / receiving device 12.

[0088] After the data phase 453, which was Fig. 4 bis Fig. 6 As shown in more detail only at the beginning and end, at the transition from the data phase 453 to the frame end phase 455, the switching phase 454 switches from the bit duration T_B2 of the data phase 453 back to the bit duration T_B1. In doing so, the operating mode Z_F_TX of the transmitting / receiving device 12 is switched to the operating mode Z_SL of the transmitting / receiving device 12.

[0089] Fig. 4 shows an example of an RxD_T signal that is driven from the transmitting / receiving device 12 to the communication control device 11. The RxD_T signal is composed of the digital signal RxD, which was generated from the signal S_SW, and the RxD_TC signal, which the communication control device 11 drives to the transmitting / receiving device 12 via the second terminal RxD. The RxD_TC signal for switching the operating mode of the transmitting / receiving device 12 has at least one inverse pulse AH_2 to the value of the bit AL1. According to the example of Fig. 4 The communication control device 11 drives the states Z, 1,0, 1, 0, Z in succession to the transmitting / receiving device 12 as the signal RxD_TC at the second terminal RxD in the switching phase 452. The state Z represents the high-impedance state. In contrast, the communication control device 11 drives the states Z, 1, 0, Z in succession as the signal RxD_TC in the switching phase 454. The signal RxD_T therefore also includes the signaling by means of the signal RxD_TC, wherein the signal RxD_TC overwrites the signal RxD_T.

[0090] In other words, in the protocol sequence, the transmitting / receiving device 12 sends or drives a bit AL1 = 0, i.e. a 0 state or low state, to the communication control device 11 at the RxD terminal or the RxD line in the signal RxD_T in the switching phase 452. However, the communication control device 11 drives the pulse pattern AH_2 on the RxD line in the bit AL1, among other things, with 1 states or high states.

[0091] In contrast, the transmitting / receiving device 12 sends or drives a bit AH1 = 1, i.e. a 1-state or high state, to the communication control device 11 at the RxD terminal or the RxD line in the signal RxD_T in the switching phase 454. However, the communication control device 11 drives the pulse pattern AL_1 on the RxD line in the bit AH1, among other things, with a 0-state or low state.

[0092] Fig. 5 shows a portion of the differential voltage signal VDIFF that appears on bus 40 due to the transmit signal TxD_T from subscriber station 10, and that was received by transceiver 12 as signal S_SW from bus 40. During normal operation, the signal states of the transmit signal TxD_T from subscriber station 10 are, without errors, identical to the digital signal RxD generated from the signal S_SW.

[0093] Fig. 6 shows a signal TxD_PC which is driven from the transmitting / receiving device 12 via the first terminal TxD to the communication control device 11 in order to provide the feedback R_S about the switching of the operating mode.

[0094] As in Fig. 4 bis Fig. 6 As shown, the communication control device 11 transmits a resXL bit in the transmission signal TxD_T according to the signal RxD_T before the switching phase 452, and in the switching phase 452 successively an AL1 bit and an AL2 bit each with a state 0 or Low Low (first binary signal state).

[0095] Then, at the end of the arbitration phase 451, based on the signal RxD_TC from Fig. 4 , switched from the bits of the arbitration phase 451 with the bit time T_B1 to the shorter bits of the data phase 453 with the bit time T_B2, as in Fig. 4 bis Fig. 6 For this purpose, the signal RxD_TC has at least one pulse or, as in the example of Fig. 4 shown, a pulse pattern AH_1 with at least two bits in the AL1 bit. The time duration T_B3 of a pulse of the pulse pattern AH_1 of Fig. 4 is approximately equal, in particular equal, or shorter than the bit time T_B2. The time duration T_B3 of a pulse of the pulse pattern AH_1 of Fig. 4 is shorter than the bit time T_B1. The AL2 bit is followed by the data of data phase 453. First, a data bit DH1 with a state of 1 or high (second binary signal state) is sent, followed by a data bit DL1 with a state of 0 or low (first binary signal state).

[0096] As can be seen from the summary of Fig. 4 und Fig. 5 As can be seen, in the switching phase 452, after the first pulse of the pulse pattern AH_2 in the receiving module 122, the receiving threshold T_a is switched to the receiving threshold T_d. After the second pulse of the pulse pattern AH_2, the physical layer is switched in the transmitting module 121. As a result, the operating mode Z_SL of the transmitting / receiving device 12 is switched to the operating mode Z_F_TX of the transmitting / receiving device 12, as shown in conjunction with Fig. 6 visible.

[0097] According to Fig. 6 The feedback R_S takes place with the module 152 in the AL2 bit. Thus, the feedback R_S takes place after the RXD signaling with at least one pulse or the pulse pattern AH_2 of the signal RxD_TC in the AL1 bit and the actual switching of the operating mode of the transmitting / receiving device 12 has taken place. The transmitting / receiving device 12 therefore sends in the example of Fig. 6 as feedback R_S in the switching phase 452 via the first terminal TxD an inverse pulse pattern with the states Z, 0, 1, 0, 1, Z, which lasts until the DH1 bit, and thus until the following edge change on the bus 40.

[0098] If the communication control device 11, or more precisely its module 111, scans the AL2 bit in the transmission signal TxD and sees the states Z, 0, 1, 0, 1, Z or at least a logical '1' or the 'High' state once in the switching phase 452, then the switching in the transmitting / receiving device 12 was performed correctly in the switching phase 452. If the communication control device 11, or more precisely its module 111, sees a logical '0' or the 'Low' state, then the switching in the transmitting / receiving device 12 was not performed correctly in the switching phase 452.

[0099] For the switchover in the switchover phase 454, the communication control device 11 signals the transmitting / receiving device 12 via the second RxD terminal in an AH1 bit (state 1 or high (second binary signal state)) the switchover to be performed with the RxD-TC signal. This is shown as an example on the right side of Fig. 4 shown. The RxD_TC signal for switching the operating mode of the transmitting / receiving device 12 in the switching phase 454 has at least one inverse pulse to the value of bit AH1.

[0100] According to Fig. 4 In the switching phase 454, the signal RxD_TC has the states Z, 0, 1, Z or at least one pulse AL_1 or one pulse pattern AL_1. After that, the reception threshold T_d is switched to the reception threshold T_a in the reception module 122. Furthermore, the physical layer is switched in the transmission module 121. This switching occurs either simultaneously with the switching of the reception module 122, as in Fig. 6 shown, or with the edge change at the end of bit AH2 (state 1 or high (second binary signal state). After that, the operating mode Z_F_TX of the transmitting / receiving device 12 is switched to the operating mode Z_SL of the transmitting / receiving device 12, as shown in conjunction with Fig. 6 visible.

[0101] If at least one of the previously described operating mode switches failed and the R_S feedback signal was not received, an error has occurred. For example, the transmitting / receiving device 32 remained in the operating mode for the first communication phase (longer bit durations), although it should have switched to the Z_F_RX operating mode for the second communication phase (shorter bit durations). The communication control device 31 will now most likely detect bit errors in the bit stream of the RxD signal via the second connection because the reception threshold in the receiving module 122 was not switched to T_d.If the communication control device 31 detects bit errors in the bit stream of the RxD signal via the second terminal, the communication control device 31 does not have to switch the transmitting / receiving device 32 to the Z_SL operating mode for the first communication phase (longer bit durations) during the subsequent error handling, because the transmitting / receiving device 32 is already in this operating mode.

[0102] If the operating mode switch in the transmitting / receiving device 32 has worked and this was correctly signaled using the signal waveform of the feedback signal R_S, the communication control device 31 knows that the transmitting / receiving device 32 is in the Z_F_RX operating mode. If the communication control device 31 detects a bit error in the bit stream of the RxD signal via the second connection, the communication control device 31 must be able to deliberately switch the transmitting / receiving device 12 from an operating mode of the second communication phase (longer bit duration) to an operating mode of the first communication phase (shorter bit duration) during the subsequent error handling, in particular with a pulse on the TXD signal. This eliminates the need to wait for the long timeouts in the transmitting / receiving device 12, which also switch the operating mode back to the operating mode of the first communication phase.This means that the transmitting / receiving device 12 (receiving node) can detect the idle condition of 11 recessive bits at the end of a transmitted frame 450 despite reception errors and can thus very quickly reintegrate into the communication on the bus 40.

[0103] Additionally, it is optionally possible for subscriber station 10 to send an error frame to abort the transmission of frame 450 or message 45. This allows transmission with incorrectly configured bus components to be aborted as quickly as possible. This increases the net data rate that can be transmitted in bus system 1. This makes communication in bus system 1 more robust.

[0104] Fig. 7 bis Fig. 9 show an example of signals before, during, and after the switching phase 452 and then before, during, and after the switching phase 454 at the subscriber station 30 (receiving node). The signals are similar or identical to the signals from Fig. 4 bis Fig. 6 . Therefore, only the differences to the signals from Fig. 4 bis Fig. 6 described

[0105] At the transition from the arbitration phase 451 to the data phase 453, the Z_SL operating mode of the transmitting / receiving device 32 is switched to the Z_F_RX operating mode of the transmitting / receiving device 12. After the data phase 453, the Z_F_RX operating mode of the transmitting / receiving device 32 is switched to the Z_SL operating mode of the transmitting / receiving device 32.

[0106] Fig. 7 shows an example of an RxD_R signal that is driven from the transmitting / receiving device 32 to the communication control device 31. The RxD_R signal is composed of the digital RxD signal, which was generated from the S_SW signal, and the RxD_TC signal, which the communication control device 31 drives to the transmitting / receiving device 32 via the second RxD terminal. The RxD_TC signal for switching the operating mode of the transmitting / receiving device 32 has at least one inverse pulse to the value of bit AL1. Fig. 7 In the switching phase 452, the RxD_TC signal has the states Z, 1, 0 in succession. The RxD_R signal also includes signaling by means of the RxD_TC signal, with the RxD_TC signal overwriting the RxD_R signal.

[0107] In other words, in the protocol sequence, the transmitting / receiving device 12 sends or drives the bit AL1 = 0, i.e. a 0 state or low state, to the communication control device 11 at the RxD terminal or the RxD line in the signal RxD_R in the switching phase 452. However, the communication control device 11 drives the pulse pattern AH_1 on the RxD line in the bit AL1, among other things, with a 1 state or high state.

[0108] In contrast, the transmitting / receiving device 12 sends or drives the bit AH1 = 1, i.e. a 1-state or high state, to the communication control device 11 at the RxD terminal or the RxD line in the signal RxD_T in the switching phase 454. However, the communication control device 11 drives the pulse pattern AL_1 on the RxD line in the bit AH1, among other things, with a 0-state or low state.

[0109] Fig. 8 shows a portion of the differential voltage signal VDIFF, which is generated on the bus 40 due to the transmit signal TxD_T from the subscriber station 10 and is received at the transmitting / receiving device 32 as signal S_SW. The signal from Fig. 8 is therefore identical to the signal from Fig. 5 .

[0110] Fig. 9 shows the signal TxD_PC, which is driven from the transmitting / receiving device 32 via the first terminal TxD to the communication control device 31 in order to provide the feedback R_S about the switching.

[0111] As in Fig. 7 bis Fig. 9 As shown, the signal RxD_TC has a pulse AH_1 in the switching phase 452, as in the example of Fig. 7 shown, or a pulse pattern AH_1 with at least two bits in the AL1 bit.

[0112] As can be seen from the summary of Fig. 7 und Fig. 8 As can be seen, after the pulse AH_1 in the receiving module corresponding to the receiving module 122, the receiving threshold T_a is switched to the receiving threshold T_d. In addition, for example, the transmitting module corresponding to the transmitting module 121 can be switched off for the data phase 453 or switched to a state 1 or high (second binary signal state). As a result, the operating mode Z_SL of the transmitting / receiving device 32 is switched to the operating mode Z_F_RX of the transmitting / receiving device 32, as shown in conjunction with Fig. 9 visible.

[0113] According to Fig. 9 The feedback R_S occurs in the AL2 bit with the module of block 35 corresponding to module 152. Thus, the feedback R_S occurs after the RXD signaling with at least one pulse or the pulse pattern AH_2 of the RxD_TC signal in the AL1 bit, as well as the actual switching of the operating mode of the transceiver device 32.

[0114] The transmitting / receiving device 32 transmits in the example of Fig. 9 In the switching phase 452, as feedback R_S in the AL2 bit via the first terminal TxD, a TxD_PC signal with at least one inverse pulse or an inverse pulse pattern, which can last up to the DH1 bit, and thus up to the following edge change on the bus 40. In Fig. 9 the signal TxD_PC has in the switching phase 454 successively the states Z, 1,0, Z. The transmitting / receiving device 32 therefore sends in the example of Fig. 9 as feedback R_S in the switching phase 452 via the first terminal TxD an inverse pulse pattern with the states Z, 1, 0, Z, which lasts until the DH1 bit, and thus until the following edge change on the bus 40.

[0115] If the communication control device 31, or more precisely its module corresponding to module 111, scans the AL2 bit in the transmit signal TxD and sees the states Z, 1, 0, Z or at least a logical '1' or the 'High' state once, then the switchover in the transmit / receive device 32 was performed correctly. If the communication control device 31, or more precisely its module 111, sees a logical '0' or the 'Low' state, then the switchover in the transmit / receive device 32 was not performed correctly.

[0116] For the switchover in the switchover phase 454, the communication control device 31 signals the transmitting / receiving device 32 via the second RxD terminal in an AH1 bit (state 1 or high (second binary signal state)) the switchover to be performed with the RxD-TC signal. This is shown as an example on the right side of Fig. 7 shown. The RxD_TC signal for switching the operating mode of the transmitting / receiving device 32 in the switching phase 454 has at least one inverse pulse to the value of bit AH1.

[0117] According to Fig. 7 the signal RxD_TC has the states Z, 0, 1, Z or at least one pulse AL_1 or one pulse pattern AL_1 in the switching phase 454. After that, in the receiving module corresponding to the receiving module 122, the receiving threshold T_d is switched to the receiving threshold T_a. In addition, in the transmitting module corresponding to the transmitting module 121, the state constant 1 or high (second binary signal state) is switched off again, so that the transmitting module of the transmitting / receiving device 32 is again in the state for the first operating mode Z_SL. This switching occurs either simultaneously with the switching of the receiving module corresponding to the receiving module 122, as in Fig. 9 shown, or with the edge change at the end of bit AH2 (state 1 or high (second binary signal state). After that, the operating mode Z_F_RX of the transmitting / receiving device 32 is switched to the operating mode Z_SL of the transmitting / receiving device 32, as shown in conjunction with Fig. 9 visible.

[0118] If at least one of the previously described operating mode switches has not worked, an error has occurred. In the event of an error, the communication control device 31 can react by proceeding for the transmitting / receiving device 32 as previously described for the subscriber station 10 with respect to Fig. 4 bis Fig. 6 described.

[0119] Optionally, a feedback signal R_S can be provided with the TxD_PC signal before switching at least the transmitting module 121. Thus, the feedback signal R_S can take place before the actual switching of the operating mode of the transmitting / receiving device 32.

[0120] The feedback R_S in the AL2 bit according to Fig. 6 or Fig. 9 is more advantageous than the feedback R_S before the actual switching of the operating mode of the transmitting / receiving device 32, since otherwise additional edges could be seen in the devices 12, 32, which would disturb or cancel the synchronization of the subscriber stations 10, 30.

[0121] Due to the previously described configuration of the subscriber station 10, no galvanic connection is required through an additional connection on the communication control device 11 and the associated transceiver 12, so that the communication control device 11 can transmit the time of the operating mode switchover and receive the feedback signal R_S. This means that the block 15 advantageously does not require an additional connection that is not available on a standard housing of the transceiver 12. Thus, the block 15 eliminates the need to switch to a different, larger and cost-intensive housing to provide an additional connection.

[0122] Furthermore, block 15 eliminates the need for a protocol controller functionality in the transmitting / receiving device 12. Such a protocol controller could, among other things, detect the switching phase 452 of message 45 and initiate the data phase 453 based on this. However, since such an additional protocol controller would require considerable space in the transmitting / receiving device 12 or the ASIC, block 15 significantly reduces resource requirements.

[0123] Thus, interconnecting the operating mode switching block 126 and block 15 with a conventional transmitting / receiving device offers a very simple and cost-effective solution for not only informing the transmitting / receiving device 12 that a switchover is to be made and which switchover is to be made between its various operating modes, namely, in particular, from the first operating mode to the second operating mode, or from the first operating mode to the third operating mode, or from the second operating mode to the first operating mode, or any other switching of operating modes. In addition, block 15 can also provide the communication control device 12 with the corresponding feedback R_S regarding the switchover in a very simple, cost-effective, and robust manner.

[0124] Due to the described configuration of the transmitting / receiving device(s) 12, 32, much higher data rates can be achieved in the data phase 452 than with CAN or CAN-FD. Furthermore, the data length in the data field of the data phase 453 can be freely selected, as previously described. This allows the advantages of CAN with regard to arbitration to be retained, while still allowing a larger volume of data to be transmitted very securely and thus effectively in a shorter time than before, i.e., without the need to repeat the data due to an error, as explained below.

[0125] A further advantage is that error frames are not required in bus system 1 when transmitting messages 45, but can be used optionally. If error frames are not used, messages 45 are no longer destroyed, eliminating one reason for the need for duplicate message transmission. This increases the net data rate.

[0126] If the bus system is not a CAN bus system, the operating mode switching block 126 can be designed or configured to respond to other switching signals. The same applies to block 15. In this case, the operating mode switching block 126 can switch the transmitting module 121 and / or the receiving module 122 to one of at least two different operating modes depending on the result of its evaluation and switch at least one of the operating modes to another of the operating modes after a time period T0 preset in the operating mode switching block 126 has elapsed. In this case, block 15 can provide the communication control device 12 with the corresponding feedback R_S regarding the switchover.

[0127] According to a second embodiment, the block 15, more precisely its module 152, sends a bit with the state 1 or high (second binary signal state) at the TxD terminal in the switching phase 452 instead of a pulse pattern. If, for example, RxD = 0 currently applies, then the respective transmitting / receiving device 12, 32 can send the bit '1' at the RxD terminal.

[0128] Otherwise, the bus system 1 in the second embodiment is constructed in the same way as previously described with reference to the first embodiment.

[0129] Thus, each of the transmitting / receiving devices 12, 32 has different options for implementing the feedback R_S with the transmit signal TxD, TxD_R, TxD_T. Based on the resulting manipulation of the transmit signal TxD, TxD_R, TxD_T, the communication control device 11, 31, in particular its module 111, detects a positive feedback R_S from the associated transmitting / receiving device 12, 32.

[0130] It is advantageous if, in the switching phases 452, 454, the RxD pulse patterns used to signal the switching and the TxD pulse patterns used to report the operating mode of the transmit / receive device 12, 32 differ in polarity and / or number of pulses. This can increase interference immunity against a wide variety of faults, for example, during ramp-up and ramp-down of the supply voltages of the entire subscriber station 10, 30.

[0131] All previously described embodiments of blocks 15, 35, subscriber stations 10, 20, 30, bus system 1, and the method implemented therein can be used individually or in all possible combinations. In particular, all features of the previously described embodiments and / or modifications thereof can be combined as desired. Additionally or alternatively, the following modifications are conceivable.

[0132] Although the invention has been described above using the CAN bus system as an example, the invention can be applied to any communication network and / or communication method that uses two different communication phases, in which the bus states generated for the different communication phases differ. In particular, the invention is applicable to the development of other serial communication networks, such as Ethernet and / or 10BaseT1-S Ethernet, fieldbus systems, etc.

[0133] The previously described bus system 1 according to the exemplary embodiments is described using a bus system based on the CAN protocol. However, the bus system 1 according to the exemplary embodiments can also be another type of communications network in which data can be transmitted serially at two different bit rates. It is advantageous, but not a mandatory requirement, that exclusive, collision-free access of a subscriber station 10, 20, 30 to a common channel is guaranteed in the bus system 1, at least for certain periods of time.

[0134] The number and arrangement of subscriber stations 10, 20, 30 in bus system 1 of the exemplary embodiments is arbitrary. In particular, subscriber station 20 can be omitted from bus system 1. It is possible for one or more of subscriber stations 10 or 30 to be present in bus system 1. It is conceivable for all subscriber stations in bus system 1 to be configured identically, i.e., only subscriber station 10 or only subscriber station 30 to be present.

[0135] The type of signaling for the switching of the operating mode of the individual transmitting / receiving devices 12, 32 can be freely selected. Additionally or alternatively, the type of feedback R_S for each individual transmitting / receiving device 12, 32 can be freely selected. Furthermore, the feedback R_S for the switching from the arbitration phase 451 to the data phase 453 can differ from the feedback R_S for the switching from the data phase 453 to the arbitration phase 451, as shown in Fig. 6 and Fig. 9 shown. Any combination of the previously described variants of the feedback signal R_S is conceivable.

Claims

1. Transmitting / receiving device (12; 32) for a subscriber station (10; 30) of a serial bus system (1), having a first connection for receiving a transmission signal (TxD) from a communication control device (11; 31), a transmitting module (121) for transmitting the transmission signal (TxD) onto a bus (40) of the bus system (1), in which bus system (1) at least a first communication phase (451, 452, 454, 455) and a second communication phase (453) are used to exchange messages (45; 46) between subscriber stations (10, 20, 30) of the bus system (1), a receiving module (122) for receiving the signal (S_SW) from the bus (40), wherein the receiving module (122) is configured to generate a digital reception signal (RxD; RxD_T; RxD_R) from the signal (S_SW) received from the bus (40), characterized by a second connection for transmitting the digital reception signal (RxD; RxD_T; RxD_R) to the communication control device (11; 31) and for receiving an operating mode switch-over signal (RxD_TC) from the communication control device (11; 31) in order to switch over between operating modes of the transmitting / receiving device (12; 32) depending on the function of the subscriber station (10; 30) in the subsequent communication phase (451, 452, 454, 455; 453), and a switch-over feedback block (15; 35) for detecting, from the output signals of the transmitting module (121) and of the receiving module (122), into which operating mode (Z_SL; Z_F_RX; Z_F_ZX) the transmitting module (121) and the receiving module (122) are switched, and for outputting feedback (R_S) about a performed switch-over of the operating mode (Z_SL; Z_F_RX; Z_F_TX) due to the operating mode switch-over signal (RxD_TC), wherein the switch-over feedback block (15; 35) is connected to the first connection for outputting the feedback (R_S) to the communication control device (11; 31) via the first connection.

2. Transmitting / receiving device (12; 32) according to Claim 1, wherein the switch-over feedback block (15; 35) has an operating mode detection module (151) for detecting, from the output signals of the transmitting module (121) and of the receiving module (122), into which operating mode (Z_SL; Z_F_RX; Z_F_ZX) the transmitting module (121) and the receiving module (122) are switched, and an operating mode feedback module (152) for evaluating an operating mode status signal (S_E) that is output by the operating mode detection module (151), wherein the operating mode feedback module (152) is configured to decide, using a result of the evaluation, whether the operating mode feedback module (152) has to give feedback (R_S) to the communication control device (11) via the digital transmission signal (TxD) and when the feedback (R_S) has to be transmitted.

3. Transmitting / receiving device (12; 32) according to either of the preceding claims, wherein the operating mode feedback module (152) is configured to insert the feedback (R_S) into the digital transmission signal (TxD) after the switch-over of the operating mode (Z_SL; Z_F_RX; Z_F_ZX) which was signalled by the operating mode switch-over signal (RxD_TC), or wherein the operating mode feedback module (152) is configured to insert the feedback (R_S) into the digital transmission signal (TxD) after the operating mode switch-over signal (RxD_TC) but before the switch-over of the operating mode (Z_SL; Z_F_RX; Z_F_ZX) which was signalled by the operating mode switch-over signal (RxD_TC).

4. Transmitting / receiving device (12; 32) according to Claim 3, wherein the operating mode feedback module (152) is configured to drive the feedback (R_S) more strongly at the beginning than at the end of the feedback (R_S).

5. Transmitting / receiving device (12; 32) according to Claim 3 or 4, wherein the operating mode feedback module (152) is configured to insert the feedback (R_S) into the digital transmission signal (TxD) as at least one pulse (AH_1) having a value which is inverse to a value of the digital transmission signal (TxD).

6. Transmitting / receiving device (12; 32) according to Claim 5, wherein the at least one pulse (AH_1) lasts up until a subsequent edge change on the bus (40), which follows in the digital transmission signal (TxD).

7. Transmitting / receiving device (12; 32) according to one of the preceding claims, additionally having an operating mode switch-over block (126) which is connected to the second connection in order to evaluate the operating mode switch-over signal (RxD_TC) received from the communication control device (11; 31) at the second connection for a switch-over of the operating mode (Z_SL; Z_F_RX; Z_F_TX), wherein the operating mode switch-over block (126) is configured to switch the transmitting module (121) and / or the receiving module (122) into one of at least three different operating modes (Z_SL; Z_F_RX; Z_F_TX) depending on a result of the evaluation.

8. Transmitting / receiving device (12; 32) according to one of the preceding claims, wherein the operating mode switch-over signal (RxD_TC) received from the communication control device (11; 31) at the second connection is at least one pulse (AH_1) having a value which is inverse to a value of the digital reception signal (RxD; RxD_T; RxD_R), wherein the operating mode switch-over block (126) is configured to switch the receiving module (122) from the first operating mode (Z_SL) to the second operating mode (Z_F_RX) if the switch-over signal (RxD_TC) has a pulse (AH_1), wherein the operating mode switch-over block (126) is configured to switch the transmitting module (121) and the receiving module (122) from the first operating mode (Z_SL) to the third operating mode (Z_F_TX) if the switch-over signal (RxD_TC) has two pulses (AH_1), wherein the transmitting / receiving device (12; 32) in the second operating mode (Z_F_RX) is not the transmitter of the message (45) in the second communication phase (453), and wherein the transmitting / receiving device (12; 32) in the third operating mode (Z_F_TX) is the transmitter of the message (45) in the second communication phase (453).

9. Transmitting / receiving device (12; 32) according to one of the preceding claims, wherein the transmitting / receiving device (12; 32) is configured to transmit, as feedback (R_S) via the first connection, at least one pulse which differs from the at least one pulse of the operating mode switch-over signal (RxD_TC) at the second connection in polarity and / or number of the pulses.

10. Transmitting / receiving device (12; 32) according to one of the preceding claims, wherein the transmitting module (121) is configured to drive bits of the signals onto the bus (40) in the first communication phase (451) with a first bit time (T_B1) which is greater by at least the factor 10 than a second bit time (T_B2) of bits which drives the transmitting module (121) onto the bus (40) in the second communication phase (453), and wherein the operating mode switch-over signal (RxD_TC) via the second connection for signalling that the switch-over of the operating mode is to be carried out has at least one pulse with a duration (T_B3) which is less than the first bit time (T_B1) and is greater than the second bit time (T_B2), or has at least one pulse with a pulse duration (T_B3) which is approximately equal to the second bit time (T_B2) or is less than the second bit time (T_B2), and wherein the feedback (R_S) via the first connection for signalling that the operating mode has been switched over has at least one pulse with a duration (T_B3) which is less than the first bit time (T_B1), and is greater than the second bit time (T_B2), or has at least one pulse with a pulse duration (T_B3) which is approximately equal to the second bit time (T_B2) or is less than the second bit time (T_B2).

11. Transmitting / receiving device (12; 32) according to one of the preceding claims, wherein the signal (S_SW) received from the bus (40) in the first communication phase (451, 452, 454, 455) is generated with a different physical layer than the signal (S_SW) received from the bus (40) in the second communication phase (453).

12. Transmitting / receiving device (12; 32) according to one of the preceding claims, wherein the first communication phase (451, 452, 454, 455) involves negotiating which of the subscriber stations (10, 20, 30) of the bus system (1) receives at least temporarily exclusive, collision-free access to the bus (40) in the subsequent, second communication phase (453).

13. Communication control device (11; 31) for a subscriber station (10; 30) of a serial bus system (1), having a communication control module (111) for generating a transmission signal (TxD) for controlling communication between the subscriber station (10; 30) and at least one other subscriber station (10; 20; 30) of the bus system (1), in which bus system (1) at least a first communication phase (451, 452, 454) and a second communication phase (453) are used to exchange messages (45; 46) between subscriber stations (10, 20, 30) of the bus system (1), a first connection for transmitting the transmission signal (TxD) to a transmitting / receiving device (12; 32) which is configured to transmit the transmission signal (TxD) onto a bus (40) of the bus system (1), and the operating mode of which is able to be switched over depending on the function of the subscriber station (10; 30) in the subsequent communication phase (451, 452, 454, 455; 453), a second connection for receiving a digital reception signal (RxD; RxD_T; RxD_R) from the transmitting / receiving device (12; 32), wherein the communication control device (11; 31) is configured to generate an additional signal (RxD_TC) which indicates that the transmit-ting / receiving device (12; 32) is to be switched from its current operating mode into a different operating mode of at least three different operating modes, and which realizes internal communication between the communication control module (111) and the transmitting / receiving device (12; 32), characterized in that the communication control module (111) is configured to transmit the additional signal (RxD_TC) to the transmitting / receiving device (12; 32) via the second connection in the digital reception signal (RxD; RxD_T; RxD_R), and in that the communication control module (111) is configured to receive feedback (R_S) about a performed switch-over of the operating mode (Z_SL; Z_F_RX; Z_F_TX) due to the operating mode switch-over signal (RxD_TC) via the first connection in the transmission signal (TxD) from the transmitting / receiving device (12; 32) and to evaluate the feedback (R_S).

14. Bus system (1) having a bus (40), and at least two subscriber stations (10; 20; 30) which are connected to one another via the bus (40) in such a way that they can communicate serially with one another and at least one subscriber station (10; 30) of which has a transmitting / receiving device (12; 32) according to one of Claims 1 to 12 and a communication control device (11; 31) according to Claim 13.

15. Method for communication in a serial bus system (1), wherein the method is carried out using a transmitting / receiving device for a subscriber station (10; 30) of a bus system (1) in which at least a first communication phase (451, 452, 454, 455) and a second communication phase (453) are used to exchange messages (45; 46) between subscriber stations (10, 20, 30) of the bus system (1), wherein the subscriber station (10; 30) has a transmitting module (121), a receiving module (122), an operating mode switch-over block (126), a switch-over feedback block (15; 35), a first connection and a second connection, and wherein the method has the steps of: receiving, by means of the receiving module (122), a signal (S_SW) from the bus (40) of the bus system (1), generating, by means of the receiving module (122), from the signal (S_SW) received from the bus (40), a digital reception signal (RxD; RxD_T; RxD_R) and outputting the digital reception signal (RxD; RxD_T; RxD_R) at the second connection, characterized by the steps of: receiving, by means of the operating mode switch-over block (126) which is connected to the second connection, the operating mode switch-over signal (RxD_TC) at the second connection from the communication control device (11; 31) in order to evaluate the received operating mode switch-over signal (RxD_TC) for a switch-over of the operating mode (Z_SL; Z_F_RX; Z_F_TX), detecting, by means of the switch-over feedback block (15; 35), from the output signals of the transmitting module (121) and of the receiving module (122), into which operating mode (Z_SL; Z_F_RX; Z_F_ZX) the transmitting module (121) and the receiving module (122) are switched, and outputting, by means of the switch-over feedback block (15; 35) which is connected to the first connection, feedback (R_S) about a performed switch-over of the operating mode (Z_SL; Z_F_RX; Z_F_TX) due to the operating mode switch-over signal (RxD_TC) via the first connection to the communication control device (11; 31).