CN115244901A

CN115244901A - Transmitting/receiving device for a subscriber station of a serial bus system and method for communication in a serial bus system

Info

Publication number: CN115244901A
Application number: CN202180023384.7A
Authority: CN
Inventors: F·哈特维奇; S·沃克尔; A·穆特尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-01-23
Filing date: 2021-01-18
Publication date: 2022-10-25
Also published as: DE102020200801A1; GB2607254A; WO2021148348A1; GB202212078D0

Abstract

A transmitting/receiving device (12, 32) for a subscriber station (10. The transmission/reception device (12: -a first connector for receiving a transmission signal (TxD) from a communication control device (11; a transmission module (121) for transmitting the transmission signal (TxD) to a bus (40) of the bus system (1), at least one first communication phase (451, 452, 454, 455) and one second communication phase (453) being used for the bus system (1) for exchanging messages (46) between user stations (10, 20, 30) of the bus system (1); a receiving module (122) for receiving signals from the bus (40), wherein the receiving module (122) is designed to generate a digital receiving signal (RxD; rxD _ T; rxD _ R) from the signals received from the bus (40); a second connection for transmitting the digital receive signal (RxD; rxD _ T; rxR _ R) to the communication control device (11) and for receiving a running mode switching signal (RxD _ TC) from the communication control device (11; and an operating mode-switching block (15, 150) for evaluating an operating mode-switching signal (RxD _ TC) received at a second connection from the communication control device (11.

Description

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

Technical Field

The invention relates to a transmitting/receiving device for a subscriber station of a serial bus system and a method for communication in a serial bus system which operates with a high data rate and a large error robustness.

Background

For communication between sensors and control devices, for example in vehicles, bus systems are generally used in which data are transmitted as messages in accordance with ISO 11898-1: the 2015 standard is transmitted as CAN protocol specification with CAN FD. Messages are transmitted as analog signals between bus users of the bus system, such as sensors, control units, transmitters, etc.

Each bus user of the bus system is connected to the bus with a transmitting/receiving device. At least one reception comparator is provided in the transmission/reception device, which receives an analog signal from the bus and converts it into a digital signal. The content of the digital signal can be interpreted by a protocol controller. Furthermore, the protocol controller can create a signal for transmission on the bus and transmit it with the transmitting/receiving device onto the bus, so that information can be exchanged between the bus subscribers.

In order to be able to transmit data via the bus at a higher bit rate than in the CAN case, options for converting to a higher bit rate within the message are provided in the CAN FD message format and in the CAN XL message format. In such a technique, the maximum possible data rate is increased by using a higher clock pulse in the region of the data field than CAN. In this case, the maximum possible data rate is increased to a value of more than 1 MBit/s for CAN FD frames or CAN FD messages. In addition, the effective data length extends from 8 bytes to 64 bytes. This applies analogously to CAN XL for which the speed of data transmission should be increased to the range of the example 10 Base-T1S ethernet and the effective data length up to 64 bytes, which has been achieved hitherto with CAN FD, should be greater. The robustness of CAN or CAN FD based communication networks CAN thereby advantageously be maintained.

During the detailed description of the analog serial data transmission on the CAN bus line, the transmission level and the reception threshold value for at least one input comparator of the transmitting/receiving device (transceiver) of each subscriber station are then specified for the CAN XL. The transmission level and the reception threshold are optimized for a design of the bus line topology that is as flexible as possible and differ in the different operating modes of the transmission/reception device (transceiver).

The disadvantage is that the bit levels of the two logics on the CAN bus line are not always unambiguously identified when the receiving transmitter/receiver is set to a reception threshold value that differs from the transmission of the transmission level on the bus. This may occur in particular when the transmitting/receiving device (transceiver) wakes up from a standstill and attempts to join the ongoing communication on the bus again. In order to be able to implement such a joining of CAN subscriber stations which do not yet know which operating mode is the correct operating mode for the transmitting/receiving device, a third receiving Threshold T _ OoB (Threshold Out-of-Bounds) with a value of, for example, -0.4V is inserted for at least one input comparator.

However, it is problematic that the reception threshold T _ OoB may interfere with synchronization of the subscriber station. The reason for this is that, when switching back from the data phase into the arbitration phase, the receive threshold T _ OoB shifts the bit edges on the taps of the transmit/receive device for the RxD signal formed by the signal received from the bus.

Disclosure of Invention

It is therefore an object of the present invention to provide a transmitting/receiving device for a subscriber station of a serial bus system and a method for communication in a serial bus system, which solve the aforementioned problems. In particular, a transmitting/receiving device for a subscriber station of a serial bus system and a method for communication in a serial bus system should be provided, in which the process of adding a CAN subscriber station to an ongoing communication is improved.

This object is achieved by a transmitting/receiving device for a subscriber station of a serial bus system having the features of claim 1. The transmission/reception device has: a first connector for receiving a transmission signal from a communication control device; a transmitting module for transmitting a transmitting signal onto a bus of a bus system, in which at least one first communication phase and one second communication phase are used for exchanging messages between user stations of the bus system; a receiving module for receiving signals from the bus, the receiving module being designed to generate digital receiving signals from the signals received from the bus; a second connector for transmitting the digital reception signal to a communication control device to receive an operation mode-switching signal from the communication control device; and an operating mode switching block for evaluating an 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 the receiving module into one of three different operating modes as a function of the result of the evaluation, and wherein the operating mode switching block is designed to delay the switching of the operating mode of the second communication phase into the operating mode of the first communication phase in time up to a bit boundary of the switching phase between the communication phases.

With the transmitting/receiving device, it is possible to prevent "false alarms" in CAN idle detection. As a result, the subscriber station can be engaged in an ongoing communication on the bus. Furthermore, the synchronization of the transmitting/receiving devices and thus of the superordinate user stations (CAN nodes) is still achieved or maintained.

Furthermore, with the transmitting/receiving device, the arbitration known from the CAN be maintained in one of the communication phases and the transmission rate CAN nevertheless be increased significantly again in relation to the CAN or CAN FD. This can be achieved by: two communication phases with different bit rates are used and the start of the second communication phase in which the useful data is transmitted with a higher bit rate than in the arbitration is reliably recognizable to the transmitting/receiving device. The transmitting/receiving device can therefore reliably switch from the first communication phase into the second communication phase or back. As a result of this, a significant increase in the bit rate and thus in the transmission speed from the sender to the receiver can be achieved. At the same time, however, a large error robustness is ensured.

Even if at least one CAN subscriber station and/or at least one CAN FD subscriber station transmitting messages according to the CAN protocol and/or the CAN FD protocol are also present in the bus system, the method implemented by the transmitting/receiving device CAN be used.

Further advantageous embodiments of the transmitting/receiving device are specified in the dependent claims.

The operating mode changeover block may be designed to carry out a changeover of the operating mode when changing over from the second communication phase into the first communication phase if edges between different bus states occur in the receive signal output by the receiving module and the transmitting/receiving device is not the sender of a message.

The operating mode switching block can be designed to switch off the transmitting module in an operating mode of a second communication phase in which the transmitting/receiving device is not the sender of a message.

If the transmitting/receiving device is the sender of a message in the second communication phase and edges between different bus states occur in the transmit signal, the operating mode changeover block may be designed to make a changeover of the operating mode when changing over from the second communication phase into the first communication phase.

The sending module may be designed to drive a bit of the signal onto the bus with a first bit time in the first communication phase, the first bit time being at least 10 times greater than a second bit time of the following bit, the sending module driving the bit onto the bus in the second communication phase. The operating mode changeover signal can have at least one pulse with a pulse duration which is approximately equal to the second bit time or shorter than the second bit time via a second terminal for signaling a changeover of the operating mode.

The communication control device can be designed to: if a transition from the first communication phase to the second communication phase is to be made, an identifier having a predetermined value is transmitted as an operating mode changeover signal to the receiving module at the terminal for the digital receiving signal.

For example, the identifier is a bit having a predetermined value or pulse pattern, or the identifier is a predetermined bit pattern.

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.

It can be considered that in the first communication phase it is agreed which subscriber station of the subscriber stations of the bus system obtains an at least temporarily dedicated, collision-free access to the bus in the subsequent second communication phase.

The transmitting/receiving device described above and the communication control device described above can be part of a subscriber station of a bus system, which furthermore comprises a bus and at least two subscriber stations, which are connected to one another via the bus in such a way that the subscriber stations can communicate serially with one another. At least one subscriber station of the at least two subscriber stations has the transmission/reception device described above.

The aforementioned object is also achieved by a method for communication in a serial bus system according to claim 13. The method is carried out using a transmitting/receiving device for subscriber stations of a bus system, wherein at least one first communication phase and one second communication phase are used for exchanging messages between subscriber stations of the bus system, wherein the subscriber stations have a transmitting module, a receiving module, an operating mode switching block, a first connection and a second connection, and wherein the method has the following steps: receiving, with the receive module, a signal from a bus of the bus system; generating a digital receive signal from the signal received by the bus with the receive module and outputting the digital receive signal at the second connection; evaluating an operating mode switching signal received at a second connection from the communication control device with the operating mode switching block; and switching the transmitting module and/or the receiving module into one of three different modes with the operation mode-switching block according to the result of the evaluation, wherein the operation mode-switching block delays the switching of the operation mode of the second communication phase into the operation mode of the first communication phase in time until a bit boundary of a switching phase between the communication phases.

The method provides the same advantages as mentioned above in relation to the transmitting/receiving means and/or the communication control means.

Other possible implementations of the invention also include combinations of features or embodiments not explicitly mentioned above or described next with respect to the embodiments. The person skilled in the art will also add individual aspects as modifications or additions to the corresponding basic forms of the invention.

Drawings

The present invention is described in detail below with reference to the drawings and according to embodiments. Wherein:

fig. 1 shows a simplified block diagram of a bus system according to a first embodiment;

fig. 2 shows a diagram for illustrating the structure of messages that can be sent by a subscriber station of the bus system according to the first embodiment;

fig. 3 shows a simplified schematic block diagram of a subscriber station of the bus system according to the first exemplary embodiment;

fig. 4 shows a circuit diagram of an operation mode-switching block for switching the operation mode of the transmitting/receiving means of the subscriber station of fig. 3;

fig. 5 to 9 show the time profile of a signal according to the first exemplary embodiment during the time phase in which the first operating mode of the transmitting/receiving device switched on in the arbitration phase (first communication phase) is switched into one of the two operating modes of the transmitting/receiving device, into which the transmitting/receiving device can be switched in the data phase as the second communication phase;

fig. 10 to 15 show time profiles of signals according to a first exemplary embodiment during the time phases in which the operating mode of the transmitting/receiving device for the second communication phase, i.e. the operating mode of the transmitting/receiving device for the data phase, is switched back to the first operating mode, which is the operating mode of the transmitting/receiving device for the arbitration phase;

fig. 15 to 17 show time profiles of signals in the subscriber station of fig. 3 when the subscriber station attempts to join an ongoing communication on the bus; and is

Fig. 18 shows a circuit diagram of an operating mode switching block for switching the operating mode of the transmitting/receiving device of the subscriber station of fig. 3 according to a second exemplary embodiment.

In the drawings, identical or functionally identical elements are provided with the same reference numerals, unless otherwise specified.

Detailed Description

Fig. 1 shows, as an example, a bus system 1 which is designed in particular substantially for a CAN bus system, a CAN FD subsequent bus system and/or variants thereof, as described below. The bus system 1 can be used in a vehicle, in particular a motor vehicle, an aircraft or the like, or in a hospital or the like.

In fig. 1, the bus system 1 has a plurality of

subscriber stations

10, 20, 30, which are each connected to a bus 40 having a first bus core 41 and a second bus core 42. The

bus cores

41, 42 CAN also be referred to as CAN _ H and CAN _ L and are used for the transmission of electrical signals after the coupling of a dominant level or the generation of a recessive level for the signals in the transmit state.

Messages

45, 46 in the form of signals can be transmitted serially between the

individual user stations

10, 20, 30 via the bus 40. The

user stations

10, 20, 30 are, for example, control devices, sensors, display devices of a motor vehicle, etc.

As shown in fig. 1, the subscriber station 10 has a communication control device 11, a transmission/reception device 12 and a switching block 15. The subscriber station 20 has communication control means 21 and transmission/reception means 22. The subscriber station 30 has communication control means 31, transmission/reception means 32 and a conversion block 35. The transmitting/receiving means 12, 22, 32 of the

subscriber stations

10, 20, 30 are each connected directly to the bus 40, even if this is not illustrated in fig. 1.

In each

subscriber station

10, 20, 30, the

messages

45, 46 are exchanged bit by bit, encoded in the form of frames, between the respective

communication control device

11, 21, 31 and the associated transmitting/receiving

device

12, 22, 32 via the TXD line and the RXD line. This will be described in more detail below.

The communication control means 11, 21, 31 are each used to control the communication of the

respective subscriber station

10, 20, 30 with at least one other subscriber station of the

subscriber stations

10, 20, 30 connected to the bus 40 via the bus 40.

The

communication control device

11, 31 creates and reads a first message 45, which is, for example, a modified CAN message 45, which is also referred to below as CAN XL message 45. Here, the modified CAN message 45 or CAN XL message 45 is constructed based on the CAN FD follow-on format, which is described in more detail with reference to fig. 2. The

communication control device

11, 31 can furthermore be designed to: the transmitting/receiving means 12, 32 are provided with or receive CAN XL messages 45 or CAN FD messages 46 as required. The

communication control device

11, 31 thus creates and reads the first message 45 or the second message 46, the first and

second messages

45, 46 being distinguished by their data transmission standard, that is to say in this case by the CAN XL or the CAN FD.

The communication control means 21 can be implemented as per ISO 11898-1:2015, in particular, as CAN FD controller or CAN protocol controller compatible with CAN FD. The communication control device 21 creates and reads a second message 46, for example a conventional CAN message or CAN FD message 46. A number of 0 to 64 data bytes CAN be included in the CAN FD message 46, which data bytes are still transmitted for this purpose at a significantly faster data rate than in conventional CAN messages. In the latter case the communication control means 21 are made like a conventional CAN FD controller.

The transmitting/receiving device 22 CAN be produced as a CAN XL transceiver, except for the differences which are described in more detail below. In addition or as an alternative, the transmitting/receiving means 12, 32 CAN be produced like a conventional CAN FD transceiver. The transmitting/receiving means 22 CAN be made like a conventional CAN transceiver or CAN FD transceiver.

The formation and subsequent transmission of messages 45 in the CAN XL format and the reception of such messages 45 CAN be carried out by the two

subscriber stations

10, 30.

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

In the arbitration phase 451, a bit, also called SOF bit and indicating the Start of a Frame (or Start of Frame), is sent, for example, at the beginning. In addition, an identifier with, for example, 11 bits is sent in the arbitration phase 451, identifying the sender of the message 45. In the arbitration, a bit-by-bit agreement is made between the

subscriber stations

10, 20, 30 by means of an identifier: which

subscriber station

10, 20, 30 wants to transmit the

message

45, 46 with the highest priority and thus obtains a dedicated access to the bus 40 of the bus system 1 in the transition phase 452 and the following data phase 453 for the next time for transmission.

In the present embodiment, in the first transition stage 452, a transition is prepared from the arbitration stage 451 to the data stage 453. In this case, protocol format information contained in at least one bit is sent, which is suitable for distinguishing CAN XL frames from CAN frames or CAN FD frames. The transition phase 452 can have a bit AL1, which bit AL1 has the bit duration T _ B1 of the bits of the arbitration phase 451 and is transmitted with the physical layer of the arbitration phase 451. The physical layer corresponds to the bit transport layer or layer 1 of the known OSI model (open systems interconnection model). Furthermore, a Data-Length Code (Data-Length Code) can be transmitted, for example, which is 12 bits long and which can then have a value of, for example, 1 to 4096, in particular up to 2048, or another value with a step size of 1, or alternatively a value of 0 to 4095 or higher. Alternatively, the data length code can comprise fewer or more bits, so that the value range and step size can have other values.

In data phase 453, the CAN XL frame 450 or the payload data of message 45 is transmitted, which CAN also be referred to as the data field of message 45. The valid data can have data, for example, a number of bytes up to 4096 bytes or more or any other number of data, depending on the value range of the data length code. At the end of the data phase 453, a checksum can be contained, for example, in a checksum field, for the data of the data phase 453, which data includes padding bits, which are each inserted as a reversal bit by the sender of the message 45 after a predetermined number of identical bits, in particular 10 identical bits. In particular, the checksum is a frame checksum F _ CRC, which is used to protect all bits of the frame 450 up to the checksum field. Thereafter, an FCP field having a predetermined value, e.g., 1100, can follow.

In this embodiment, a transition from the data phase 453 to the end of frame phase 455 is prepared in the second transition phase 454. Here, protocol format information contained in at least one bit is sent, which is suitable for implementing the conversion. The translation stage 454 can have a bit AH1 with the bit duration T _ B1 of the bits of the arbitration stage 451, but sent with the physical layer of the data stage 453.

In the end of frame phase 455, at least one acknowledgement bit ACK can be included after the two bits AL2, AH2 in the end field in the end of frame phase 455. Thereafter, a sequence of 11 identical bits CAN follow indicating the end of the CAN XL frame 450. With at least one acknowledgement bit ACK it CAN be signaled whether the receiver has found an error in the received CAN XL frame 450 or in the message 45.

The physical layer as in CAN and CAN-FD is used at least in the arbitration phase 451 and the end-of-frame phase 455. In addition, physical layers as in CAN and CAN-FD CAN be used at least partially, i.e. at the beginning, in the first switching phase 452. In addition, physical layers as in CAN and CAN FD CAN be used at least partially in the second conversion phase 454, i.e. at the end.

An important point during said

phases

451, 455, at the beginning of phase 452 and at the end of phase 454 is to use the known CSMA/CR method which allows the

subscriber station

10, 20, 30 to access the bus 40 simultaneously, without corrupting the

messages

45, 46 with higher priority. It is thus possible to add further

bus subscriber stations

10, 20, 30 to the bus system 1 relatively easily, which is very advantageous.

The CSMA/CR method has as a result that there must be a so-called recessive state on the bus 40, which can be overwritten by

other user stations

10, 20, 30 with a dominant state on the bus 40.

Only if the bit time is significantly longer than twice the signal transmission time between two

arbitrary subscriber stations

10, 20, 30 of the bus system 1 can arbitration take place at the beginning of a frame 450 or a

message

45, 46 and acknowledgement take place in a frame end phase 455 of a frame 450 or a

message

45, 46. Thus, the bit rate in the arbitration phase 451, the end of frame phase 455, and at least partially in the transition phases 452, 454, is selected to be slower than in the data phase 453 of frame 450. In particular the bit rate in said

stages

451, 452, 454, 455 is selected to be 500 kbit/s, resulting in a bit time of about 2 mus, while the bit rate in said data stage 453 is selected to be 5 to 10 Mbit/s or more, resulting in a bit time of about 0.1 mus or less. Thus, the bit time of the signals in the other communication phases 451, 452, 454, 455 is at least 10 times greater than the bit time of the signals in the data phase 453.

The sender of the message 45, for example the subscriber station 10, only starts the transmission of the bits of the transition phase 452 and the subsequent data phase 453 onto the bus 40 if the subscriber station 10 has won arbitration as the sender and the subscriber station 10 therefore has exclusive access to the bus 40 of the bus system 1 as the sender for transmission. The sender can either switch to a faster bit rate and/or other physical layer after a portion of the transition phase 452, or switch to a faster bit rate and/or other physical layer only with the first bit of the subsequent data phase 453, i.e., as it begins.

In general, in the bus system with CAN XL, the following differential properties CAN be achieved in particular in comparison with CAN or CAN FD:

a) According to the CSMA/CR-method, the validated properties responsible for the robustness and user-friendliness of CAN and CAN FD, in particular the frame structure with identifiers and arbitration, are received and, if necessary, adapted,

b) The net data transmission rate is increased to about 10 megabits per second, and

c) The size of the valid data per frame is increased to about 4 kbytes or any other value.

Fig. 3 shows the basic structure of the subscriber station 10 with the communication control means 11, the transmit/receive means 12 and the conversion block 15. The subscriber station 30 is constructed in a similar manner to that shown in fig. 3, except that the block 35 is provided separately from the communication control means 31 and the transmitting/receiving means 32. Therefore, the temperature of the molten metal is controlled, the subscriber station 30 and the block 35 will not be separately described. The functions described below of the conversion block 15 are present identically in the conversion block 35.

According to fig. 3, the communication control device 11 also has a communication control module 111, a transmit signal output driver 112 and an RxD connector configuration module 113. The communication control device 11 is designed as a microcontroller or has a microcontroller. The communication control means 11 process signals for any application, for example control devices for motors, safety systems for machines or vehicles or other applications.

However, a system ASIC (ASIC = application specific integrated circuit) is not shown in fig. 3, which can alternatively be a System Base Chip (SBC) on which various functions necessary for the electronic assembly of the subscriber station 10 are incorporated. In particular, the transmission/reception device 12 and a not shown energy supply device for supplying the transmission/reception device 12 with electrical energy can be installed in the system ASIC. The energy Supply device typically supplies a voltage CAN Supply of 5V. However, the energy supply device can provide other voltages having other values and/or can be designed as a current source, as required.

According to fig. 3, the transmission/reception device 12 furthermore has a transmission module 121, a reception module 122, a driver 123 for the transmission signal TxD, a reception signal output driver 124 and a driver 125 which outputs the signal RxD _ TC to the conversion block 15. The conversion block 15 forms an operating state switching signal S _ OP for switching the transmission module 121 and/or the reception module 122 from the signal RxD _ TC and the signal S _ SW (which is an output signal of the reception module 122). In addition, the switching block 15 forms an operating state switching signal S _ OPT for switching the reception threshold of the reception module 122 from the signal S _ OP and the signals TxD, S _ SW. The switching signal S _ OP can include, for example, a switching signal for the transmitting module 121 and the receiving module 122 in one bit. Alternatively, the switching signal S _ OP can be a signal with a width of two bits for separately controlling the transmitting module 121 and the receiving module 122 by: for example, the first bit is set for switching the transmitting module 121 and the second bit is set for switching the receiving module 122. Of course, any alternative possibilities of the design of the switching signal S _ OP can be envisaged. The transmitting module 121 is also referred to as a transmitter. The receiving module 122 is also referred to as a receiver.

The switching block 15 can be designed as a switching block, which has in particular at least one flip-flop. This is described in more detail below with reference to fig. 4-14.

Even though reference is always made below to the transmitting/receiving device 12, it is alternatively possible to provide the receiving module 122 in a separate device outside the transmitting module 121. The transmitting module 121 and the receiving module 122 can be constructed as in the conventional transmitting/receiving apparatus 22. The transmitting module 121 can have, in particular, at least one operational amplifier and/or transistor. The receiving module 122 can have, in particular, at least one operational amplifier and/or transistor.

As shown in fig. 3, the transmitting/receiving device 12 is connected to a bus 40, more precisely to its first bus core 41 for CAN _ H and its second bus core 42 for CAN _ L. The first and

second bus conductors

41, 42 are connected in the transmitting/receiving device 12 to a transmitting module 121 and a receiving module 122. The voltage supply of the energy supply device for supplying the first and

second bus conductors

41, 42 with electrical energy is carried out as usual. The connection to ground or CAN _ GND is usually realized. This applies analogously to the termination of the first and

second bus conductors

41, 42 with a terminating resistor.

The conversion block 15 is designed to recognize the start of the

respective conversion phase

452, 454 in a message 45 received from the bus 40 and then to convert the characteristics of the transmitting/receiving device 12. The switching block 15 can switch between the following operating modes of the transmitting/receiving device 12:

a) A first mode of operation: the transmit/receive characteristics used in the arbitration phase 451,

b) The second operation mode: as a sending/receiving feature for the data phase 453 at the sender (sending node), the sending/receiving means 12 acts as a sender of the message 45 or the frame 450 and thus also as a recipient of the message 45 or the frame 450,

c) The third operating mode: as a transmission/reception characteristic of the recipient (receiving node) for the data phase 453, the transmitting/receiving device 12 is not a sender, but merely acts as a recipient of the message 45 or the frame 450.

As described below, the RxD connector configuration module 113 configures the connector RxD using the signals S1, S2 at its inputs depending on the necessary communication direction. This signal S1, which can be referred to as RxD _ out _ ena, does not allow the additional signal RxD _ TC to be driven via the RxD connection (first connection-operating mode) or allows the additional signal RxD _ TC to be driven via the RxD connection (second connection-operating mode). The signal S2 can be referred to as RxD _ out _ val. Depending on the value of signal S2, communication control device 11 actuates connection RxD at the time of the changeover between the two different communication phases in order to signal to transmitting/receiving device 12 the operating mode to be set, i.e. on the one hand in first changeover phase 452 for the changeover between arbitration phase 451 and data phase 453 and on the other hand in second changeover phase 454 for the changeover between data phase 453 and end-of-frame phase 455. Optionally, the communication control device 11 can drive the terminal RxD depending on the value of the signal S2 in a third terminal operating mode, which can also be referred to as "talk mode", in which internal communication between the

devices

11, 12 is possible. In other respects, as is usual in particular in CAN, the connection RxD is an Input (Input) for the communication control device 11, i.e. not an output as described above, so that the communication control device 11 does not drive the connection RxD. The connection RxD can therefore be operated bidirectionally by means of the RxD connection configuration module 113 and the signals S1, S2. In other words, the tap RxD is a bidirectional tap.

For this purpose, the communication control device 11 and the output driver 124 are designed such that the communication control device 11 drives the connection RxD more strongly than the output driver 124 when driving for signaling purposes. This avoids that the value of the RxD line may be indeterminate if both the communication control device 11 and the output driver 124 drive the connection RxD and a superposition of two signal sources occurs at the connection RxD. Therefore, the communication control device 11 always succeeds when such a superposition of two signal sources occurs at the connection RxD. Thereby, the value of the RxD line is always determined.

Thus, the conversion block 15 can provide the following possibilities, namely: the setting of one of the three previously mentioned operating modes in the transmit/receive device 12, which form different operating states of the transmit/receive device 12, is signaled via the RxD terminal. For this purpose, no additional connections are required at the transmitting/receiving device 12 and therefore also at the communication control device 11.

For this purpose, according to fig. 3, the conversion block 15 is provided with three inputs via which the signal RxD _ TC, the signal TxD and the signal S _ SW are fed into the conversion block 15. The signal RxD _ TC is based on a signal which is transmitted by the communication control device 11 to the transmitting/receiving device 12 via a connection for RxD signals. The communication control device 11 signals the transmitting/receiving device 12 with the signal RxD _ TC on the one hand: the transmitting/receiving device 12 must now make a transition into the operating mode for the data phase 453. At the end of the data phase 453, the communication control device 11 can switch the transmit/receive device 12 with the signal RxD _ TC from the operating mode of the data phase 453 into the operating mode for the arbitration phase 451. Furthermore, as mentioned above, any other information can be transmitted by the communication control device 11 together with the signal RxD _ TC to the transmission/reception device 12.

According to fig. 3, the transmit/receive means 12 lead the signal RxD _ TC from the connection RxD via a driver 125 to the connection for the signal RxD _ TC of the conversion block 15. And the signal S _ SW is generated from a signal received from the bus 40. The signal RxD _ TC is led to the conversion block 15 between the tap for the RxD signal and the output of the receive signal driver 124. The signal S _ SW is directed from the output of the receive module 122 and before the input of the receive signal driver 124 to the switch block 15.

According to the particular example shown in fig. 4, the conversion block 15 has two D flip-

flops

151, 152, into which the signal RxD _ TC is input as a clock signal. The two D flip-

flops

151, 152 are responsive to rising clock edges of the clock signal, signal RxD _ TC. Furthermore, a high state or a first binary signal state is loaded with the signal S _ H at the input of the D flip-flop 151. Further, the inverted signal S _ SW is input to the D flip-

flops

151 and 152 as a reset signal. The signal S _ SW is directed through an inverter 155 before being input into the D flip-

flops

151, 152. The D flip-

flops

151, 152 are connected to

logic gates

156, 157, i.e. to-gate 156 and or-gate 157. The output of the or-gate 157 is fed as a clock signal TO a D flip-flop 158, into which a time-out signal S _ TO is also fed as a reset signal, which indicates the expiration of a predetermined time duration T0. The signal S _ TO becomes active if no edge is found on the bus 40 for a predetermined duration T0, for example 11 bit times. The D flip-flop 158 responds to rising clock edges. Further, an inverter 159 is connected between the D flip-flop 158 and the input of the and-gate 156. In the particular example of fig. 4, the third D flip-flop 158 is switched from 0 to 1 by both falling edges of the signal RxD _ TC when the signal S _ SW is high. If the flip-flop 158 is at 1, it is switched from 1 to 0 by the falling edge of the signal RxD _ TC when the signal S _ SW is high. When the signal S _ SW is low, the two D flip-

flops

151, 152 are reset and do not respond to the rising edge of the signal RxD _ TC.

By means of block 160, the transmitting/receiving device 12 is able, on the transition from the data phase 453 to the end-of-frame phase 455, to first store a transition signal RxD _ TC which contains at least one high pulse driven by the communication control device 11. This will be described in more detail below with reference to fig. 5 to 14.

Of course, the above-described switching conditions can be defined differently, for example, when the signal S _ SW is low, for example, there is a rising edge on the signal RxD _ TC. Furthermore, other levels and/or other numbers of edges are possible along with other circuitry in the conversion block 15.

In the particular example of fig. 4, the D flip-flop 158 drives a binary operating state switching signal S _ OP. If the switching signal S _ OP should be of a width of two bits or if more than two operating states should be displayed, an additional D flip-flop with different transition conditions than the previously described case is required.

If the switching block 15 recognizes a switching phase 452, the operating state of the transmitting module 121 and/or of the receiving module 122 and thus the operating mode of the transmitting/receiving device 12 is switched by means of the signal S _ OP output by the switching block 15. This is explained in detail with reference to fig. 5 to 9.

In operation of bus system 1, if subscriber station 10 acts as a sender, transmission module 121 converts transmission signal TxD of communication control device 11 into corresponding signals CAN _ H and CAN _ L for

bus cores

41, 42 and transmits these signals CAN _ H and CAN _ L onto bus 40, as shown in fig. 5 for the transition from arbitration phase 451 via conversion phase 452 to data phase 453. In this case, a transition is made from the bit duration T _ B1 of the arbitration phase 451 to the shorter bit duration T _ B2 of the data phase 453. Even though the signals CAN _ H and CAN _ L are mentioned here for the transmitting/receiving device 12, these are understood as signals CAN _ XL _ H and CAN _ XL with respect to the message 45, which in the data phase 453 differ from the conventional signals CAN _ H and CAN _ L in at least one characteristic, in particular with respect to the formation of bus states for different data states of the signal TxD and/or with respect to the voltage or the physical layer and/or the bit rate. In the example of fig. 5, in data phase 453, the signals CAN _ XL _ H and CAN _ XL differ from the conventional signals CAN _ H and CAN _ L in

phases

451, 452 with respect to the development of the bus state for the different data states of signal TxD and with respect to the voltage or the physical layer and the bit rate.

As shown in fig. 6, a differential signal VDIFF = CAN _ H-CAN _ L is formed as a result of the signals on the bus 40. In addition to the idle state or stand-by state (idle or standby), the transmitting/receiving device 12 with the receiving module 122 in normal operation always listens to the transmission of data or

messages

45, 46 on the bus 40, and this is independent of whether the subscriber station 10 is the sender of the message 45. Here, the receive module 122 uses the receive threshold T _ a in the arbitration phase 451 and at the beginning of the transition phase 452. At the end of the transition phase 452 and in the data phase 453, the receive module 122 uses only the receive threshold T _ d of 0V or between +/-0.1V. The minimum value of the differential voltage for bus state D0 in the data phase 453 is referred to as VDIFF _ D0_ Min, which is within the lower range for the receive threshold T _ a. In this case, the receive module 122 forms the signal S _ SW and forwards it as a digital receive signal RxD via the receive signal output driver 124 to the communication control device 11, as shown in fig. 3. If the transmitting/receiving means 12 is switched into the operating mode for the arbitration phase 451, the means 12 cannot reliably recognize the "0" bit of the data phase 453, since the current switching threshold or reception threshold T _ a is within its lower tolerance range and therefore may be below VDIFF _ D0_ min.

Fig. 7 shows a part of a transmit signal TxD which is transmitted, for example, by the subscriber station 10 onto the bus 40. With a Delay duration T _ TLD occurring in operation, which is also referred to as the Transmitter Loop Delay (Transmitter Loop Delay), the subscriber station 10 receives a signal as a Transmitter and forms a digital received signal RxD _ T from the intermediate receiver module 122 and the driver 124, as shown in fig. 8. The delay period T _ TLD depends on the temperature, operating voltage and production tolerances and is usually specified in the data sheet of the transmitting/receiving device 12 and specified within tolerance limits. Ideally there is no delay duration T _ TLD.

According to fig. 5 to 7, the communication control device 11 transmits an FDF bit and an XLF bit, each having a high state (first binary signal state), in the transmission signal TxD before the switching phase 452. Thereafter follows the resXL bit, which is transmitted with a state low (second binary signal state) and followed by the AL1 bit transmitted with a state low (second binary signal state). Then, at the end of the arbitration phase 451, the bit of the arbitration phase 451 with the bit time T _ B1 is switched over to the bit level and switching threshold of the data phase 453 and with the bit time T _ B2 as a result of the signal RxD _ TC shown in fig. 8 and with the pulse duration T _ B3, as shown in fig. 5 to 9. The pulse duration T _ B3 is substantially equal to, smaller than or shorter than the bit time T _ B2. In particular, the pulse duration T _ B3 is equal to the bit time T _ B2. The pulse duration T _ B3 is smaller or shorter than the bit time T _ B1. The AL1 bit is followed by bits DH1, DL1 of the data phase 453 and then by valid data. The signal RxD _ TC merely switches the

analog components

121, 122 of the transmitting/receiving device 12. The length of the bit times T _ B1, T _ B2 is merely converted within the digital communication control device 11.

According to fig. 9, the subscriber station 30 (which is, for example, only the receiver of the signal from the Bus 40) receives the signal from the Bus 40 with an additional Delay duration T _ BLD, which is also referred to as a Bus Line Delay (Bus Line Delay). The subscriber station 30 forms a digital receive signal RxD _ R therefrom, as shown in fig. 9. Therefore, the receive signal RxD _ R is additionally delayed by a delay duration T _ BLD compared to the receive signal RxD _ T.

Thus, according to fig. 8, the transmit/receive device 12 of the subscriber station 10 sees a receive signal RxD _ T which has two high pulses AL _2 in the AL1 bit with the second binary signal state (Low) in a different manner than the previously described profile of the TxD signal of fig. 7. In other words, the communication control device 11 sends a signal RxD _ TC via the RxD connection, in which signal an identifier in the form of two pulses AL _2 with a first binary signal state (high), i.e. opposite signal states, is sent in the AL bit. The transmitting/receiving device 12 is thereby signaled to switch from its first operating mode into its second operating mode in order to generate the bus signals CAN _ H, CAN _ L from the following bits of the transmission signal TxD. The signal RxD _ TC causes a transition on an edge S _ TD with a transition block 15. In the second operating mode, the subscriber station 10 acts as a sender and receiver of messages 45 or frames 450.

According to fig. 9, the transmit/receive device 32 of the subscriber station 30, on the other hand, sees a receive signal RxD _ R which differs from the previously described profile of the TxD signal of fig. 7 by a high pulse AL _1 in the AL1 bit. In other words, the communication control device 31 sends a signal RxD _ TC via its RxD connection, in which an identifier in the form of a pulse AL _1 with a first binary signal state (high), i.e. with the opposite signal state, is sent in the AL bit. This signals the transmitting/receiving device 32 to switch from its first operating mode into its third operating mode. The signal RxD _ TC causes a conversion with the conversion block 15 on the edge S _ RD. In the third operating mode, the user station 30 acts only as a receiver of the frame 450, i.e. the user station 30 has lost previous arbitration or currently has no message 45 to send.

The signaling can therefore be carried out such that a sequence of two high pulses AL _2 indicates a transition from the arbitration phase 451 (first operating mode) to the data phase 452 as sender (second operating mode), as shown in fig. 8, and a high pulse AL _1 indicates a transition from the arbitration phase 451 (first operating mode) to the data phase 452 as receiver (third operating mode), as shown in fig. 9. Thereafter, transmission of the data field 453 of the frame 450 can be performed.

The time delay of the block 160 is adjusted to the value zero when the operating mode of the transmitting/receiving device 12 changes from the first operating mode (arbitration) to the second or third operating mode. Thus, the receive module 122 immediately switches its receive threshold T _ a of the arbitration stage 451 to the receive threshold T _ d of the data stage 453. If the transmission/reception device 12 is to be switched into the second operating mode, i.e. if the transmission/reception device 12 acts as a sender of a frame 450, the transmission module 121 switches when the transmission signal TxD switches to low (second signal state). Of course, other switching conditions can also be envisaged.

As can be seen from fig. 10 to 14, the transmitting/receiving device 12 proceeds as follows when transitioning from the data phase 453 to the end-of-frame phase 455. As shown in fig. 13, the transmission/reception device 12 first stores, by means of a block 160, a switching signal RxD _ TC which contains a low pulse driven by the communication control device 12. The block 160 then waits for an edge on the TxD signal according to fig. 12 and then simultaneously switches its transmit module 122 and the receive threshold of its receive module from the receive threshold T _ d of the data phase 453 to the receive threshold T _ a for arbitration, i.e. the switching threshold of its receive comparator. In addition, the transmitting/receiving device 12 switches on the reception Threshold T _ OoB (Threshold Out-of-Bounds) for its reception comparator in the receiving module.

In contrast, the transmitting/receiving device 32 (which in the example shown is merely the receiver of the frame 450) processes as it emerges from the data phase 453 as can be seen from fig. 11 and 14. The transceiver 32 waits for the edge S _ TH on the bus 40, i.e. the edge of the signal S _ SW, and only then switches the reception threshold of its receiving module from the reception threshold T _ d of the data phase 453 to the reception threshold T _ a for arbitration, i.e. the switching threshold of its receiving comparator. In addition, the transmitting/receiving device 32 switches on the reception Threshold T _ OoB (Threshold Out-of-Bounds) for its reception comparator in the receiving module.

In other words, the

communication control device

12, 32 signals the transmitting/receiving

device

12, 32 to which it belongs to switch the operating mode of the transmitting/receiving

device

12, 32, and the transmitting/receiving

device

12, 32 delays the switching until the transmitting/receiving

device

12, 32 identifies a bit boundary. The transmit/receive means 12 in the transmitting party recognizes the bit boundary on the edge on the TxD input pin. The transmitting/receiving

device

12, 32 in the receiving party (which is not the sender of the frame 450) recognizes the bit boundary on the edge on the CAN bus 40.

This prevents the receive threshold T _ OoB from disturbing the mode of operation of the transmit/receive device 12 switching back from the data phase 453 to the arbitration phases 455, 451 by shifting the second edge of the AH1 bit on the RxD tap. This does not disturb the synchronization of the

subscriber stations

10, 20, 30 of the bus system 1, which would otherwise be shifted by the shift of the second edge of the AH1 bit on the RxD connection.

The reception threshold T _ OoB can therefore be used when joining the

subscriber station

10, 20, 30 to an ongoing communication, as shown in fig. 15 to 17. For this purpose, the

subscriber station

10, 20, 30 looks for an uninterrupted sequence of 11 recessive bits, i.e. RxD =1 or RxD _ R =1 or RxD _ T =1. Thereafter, the bus is identified as being idle, i.e., in a quiescent state. This sequence of 11 recessive bits occurs between the dominant ACK bit of one CAN frame 450 and the start bit SOF of the next CAN frame 450 or even when no frame 450 is transmitted at all.

In the example of fig. 15-17, communication on the bus 40 occurs after transition from

stage

451, 452 to data stage 453. The subscriber station which has been switched on first serves only as a receiver and here generates the receive signal RxD _ R as signal RxD, as is shown in fig. 17. Such as subscriber station 10. Therefore, for the subscriber station 10, the transmit/receive means 12 are first switched into the operating mode for the arbitration phase 451 after being switched on. In this case, the reception thresholds T _ a, T _ OoB are switched on for the reception module 122, as shown in fig. 16. Because the receive Threshold T _ a of the arbitration stage 451 cannot reliably identify a logic "0" bit in the data stage 453, the receive Threshold T _ OoB (Threshold Out-of-Bounds) has become necessary. The reason for this is that the reception threshold T _ a is in the range from 0.5V to 0.9V depending on manufacturing tolerances, temperature and operating voltage, as specified in ISO 11898-2. If the differential voltage VDIFF is above the range, rxD = "0" = dominant. If the differential voltage VDIFF is below the range, rxD = "1" = recessive. If the differential voltage VDIFF is within the mentioned range, rxD is indeterminate. A logical "0" should be sent as VDIFF =1V in data phase 453. If this voltage decays to VDIFF =0.8V at the receiving subscriber station (receiving node) via the bus line, this voltage VDIFF with the reception threshold T _ a cannot be reliably recognized.

According to fig. 17, the subscriber station 10 forms a received signal RxD _ R from the signals received from the bus 40 according to fig. 15 and 16, depending on the reception thresholds T _ a and T _ OoB. The state DA _ R (which is used for the voltage value U of the differential voltage VDIFF = CAN _ H-CAN _ L not above the upper limit of the tolerance range specified for the reception threshold value T _ a) is identified as recessive, for example. In contrast, state D _ D (whose differential voltage is below the receive threshold T _ OoB) is identified as dominant. This also applies to the state D _ D present at the time t 1. Due to the tolerances described above, the value for the threshold T _ a is in the range of 0.5V to 0.9V.

Thus, the receive threshold T _ OoB causes the "1" bit in data phase 453 to be output as a "0" bit and compensates for the "0" bit so unrecognized if its differential voltage VDIFF is attenuated to within the unsafe range of T _ a. Thus, the reception threshold T _ OoB prevents: such a subscriber station erroneously recognizes the sequence of data bits as a quiescent state of the bus 40 and therefore assumes that the CAN bus 40 is free and therefore starts its own frame, which interferes with the frame that has been currently transmitted.

With the previously described embodiment of the subscriber station 10, no electrical connection needs to be made via additional connections to the communication control device 11 and to the transmitting/receiving device 12 connected thereto, respectively, so that the communication control device 11 can transmit bit levels and switching threshold switching times or other data to the transmitting/receiving device 12. That is, the block 15 advantageously does not require additional joints that are not available on standard housings of the transmitting/receiving device 12. Thus, no additional large and costly housing needs to be replaced by the block 15 to provide additional connections.

Furthermore, the operation mode-conversion block 15 allows the transmission/reception apparatus 12 not to require a protocol controller function. Such a protocol controller is able to identify, among other things, the transition phase 452 of the message 45 and initiate the data phase 453 accordingly. However, since such an additional protocol controller requires a considerable amount of area in the transmitting/receiving device 12 or ASIC, the operating mode conversion block 15 achieves a significant reduction in resource requirements.

The connection of the operating mode switching block 15 to a conventional transmitting/receiving device thus provides a very cost-effective and cost-effective solution, so that the transmitting/receiving device 12 can see between its different operating modes and what switching should take place, 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 to carry out a further switching of the operating modes.

By means of the described design of the transmitting/receiving

device

12, 32, a much higher data rate CAN be achieved in the data phase 452 than CAN or CAN FD CAN. Further, as described above, the data length in the data field of the data stage 453 can be arbitrarily selected. The advantages of CAN with regard to arbitration CAN be maintained and a larger amount of data CAN nevertheless be transmitted very reliably and thus efficiently in a shorter time than hitherto, i.e. without the need for data to be repeated due to errors, as explained below.

A further advantage is that no error frames are required in the bus system 1 when transmitting the message 45, which can however optionally be used. If no error frame is used, the message 45 is no longer corrupted, which eliminates the reason for the necessity of dual transmission of the message. Thereby increasing the net data rate.

If the bus system is not a CAN bus system, the operating

mode switching block

15, 35 CAN be designed or will be designed to respond to further switching signals. In this case, the operating

mode switching block

15, 35 can switch the transmitting module 121 and/or the receiving module 122 into one of at least two different operating modes as a function of the result of its evaluation and switch at least one of the operating modes into the other of the operating modes after expiration of the duration T0 preset in the operating

mode switching block

15, 35.

Fig. 18 shows a variant for a conversion block 150 which can be used in the subscriber station 10 according to the second exemplary embodiment instead of the conversion block 15.

Unlike the previous embodiment, the conversion block 150 uses the signal S _ OP as input information instead of the signal RxD _ TC. In this way, the advantages of the former embodiment can be obtained.

Otherwise, the bus system 1 in the second exemplary embodiment is constructed in the same manner as described above with respect to the first exemplary embodiment.

All previously described embodiments of the

blocks

15, 35, 150,

user stations

10, 20, 30, bus system 1 and methods implemented therein can be used individually or in all possible combinations. In particular, all features of the embodiments described above and/or modifications thereof can be combined in any desired manner. In addition or as an alternative, the following modifications can be considered in particular.

Although the invention has been described above using a CAN bus system as an example, it CAN be used in every communication network and/or communication method in which two different communication phases are used, in which the resulting bus states differ for the different communication phases. In particular, the invention can be used in the development of other serial communication networks, such as ethernet and/or 10 Base-T1S ethernet, fieldbus systems, etc.

The previously described bus system 1 according to the exemplary embodiment is described with the aid of a bus system based on the CAN protocol. However, the bus system 1 according to the described embodiment can also be another type of communication network, in which data can be transmitted serially with two different bit rates. It is advantageous, but not mandatory, that in the bus system 1, at least for certain time intervals, a dedicated, collision-free access of the

subscriber stations

10, 20, 30 to a common channel is ensured.

In the bus system 1 of the exemplary embodiment, the number and arrangement of the

subscriber stations

10, 20, 30 is arbitrary. In particular, the user station 20 can be omitted from the bus system 1. It is possible that one or more of the

user stations

10 or 30 are present in the bus system 1. It is conceivable that all subscriber stations in the bus system 1 are of identical design, i.e. that only subscriber station 10 or only subscriber station 30 is present.

Claims

1. Transmitting/receiving device (12:

-a first connector for receiving a transmission signal (TxD) from a communication control device (11;

transmitting module (121) for transmitting the transmission signal (TxD) to a bus (40) of the bus system (1), at least one first communication phase (451, 452, 454, 455) and one second communication phase (453) being used for the bus system (1) for exchanging messages (45) between subscriber stations (10, 20, 30) of the bus system (1);

a receiving module (122) for receiving signals from the bus (40), wherein the receiving module (122) is designed to generate a digital receiving signal (RxD; rxD _ T; rxD _ R) from the signals received from the bus (40);

a second connection for transmitting the digital receive signal (RxD; rxD _ T; rxR _ R) to the communication control device (11, 31) and for receiving an operating mode changeover signal (RxD _ TC) from the communication control device (11; and

-an operation mode-switching block (15,

wherein the operating mode switching block (15

Wherein the operating mode conversion block (15.

2. The transmit/receive device (12, 32) as claimed in claim 1, wherein the operating mode switching block (15: if an edge between different bus states occurs in a receive signal (S _ SW) output by the receive module (122) and the transmitting/receiving device (12, 32) is not the sender of the message (45), a changeover to the operating mode takes place when changing over from the second communication phase (453) into the first communication phase (454, 455, 451, 452).

3. The transmitting/receiving device (12, 32) as claimed in claim 1 or 2, wherein the operating mode switching block (15.

4. The transmit/receive device (12, 32) as claimed in claim 1 or 2, wherein the operating mode switching block (15: if the transmitting/receiving device (12.

5. The transmitting/receiving device (12: driving bits of the signal onto the bus (40) in the first communication phase (451) with a first bit time (T _ B1) that is at least 10 times greater than a second bit time (T _ B2) of bits that the sending module (121) drives onto the bus (40) in the second communication phase (453).

6. The transmit/receive device (12, 32) as claimed in claim 5, wherein the operating mode-changeover signal (RxD _ TC) has at least one pulse with a pulse duration (T _ B3) by means of a second tap for signaling a changeover of operating mode, the pulse duration (T _ B3) being approximately equal to the second bit time (T _ B2) or shorter than the second bit time (T _ B2).

7. The transmitting/receiving device (12: if a transition from the first communication phase (451, 452) into the second communication phase (453) is intended, an identifier (AL _1, AL _2) having a predetermined value is transmitted to the receiving module (122) as a running mode transition signal (RxD _ TC) at a connection for the digital receiving signal (RxD).

8. The transmitting/receiving device (12.

9. The transmitting/receiving device (12, 32) according to claim 7, wherein the identifier (AH _2.

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

11. The transmitting/receiving device (12, 32) according to one of the preceding claims, wherein in the first communication phase (451, 452, 454, 455) it is agreed which of the subscriber stations (10, 20, 30) of the bus system (1) in the subsequent second communication phase (453) obtains an at least temporarily dedicated, collision-free access to the bus (40).

12. Bus system (1) with

A bus (40), and

at least two user stations (10.

13. Method for communication in a serial bus system (1), wherein the method is carried out using a transmitting/receiving device for subscriber stations (10, 30) of the bus system (1), wherein at least one first communication phase (451, 452, 454, 455) and one second communication phase (453) are used for exchanging messages (45,

receiving signals from a bus (40) of the bus system (1) with the receiving module (122),

generating a digital reception signal (RxD; rxD _ T, rxD _ R) from the signals received by the bus (40) by means of the reception module (122) and outputting the digital reception signal (RxD; rxD _ T, rxD _ R) at the second connection,

-evaluating an operating mode-switching signal (RxD _ TC) received at the second connection from the communication control device (11

Switching the transmitting module (121) and/or the receiving module (122) into one of three different operating modes with the operating mode-switching block (15,

wherein the operating mode-switching block (15.