WO2021028269A1 - Conflict detector for a subscriber station of a serial bus system and method for communication in a serial bus system - Google Patents

Abstract

The invention relates to a conflict detector (15; 15A; 15B; 15C; 25; 35) for a serial bus system (1) and a method for detecting a bus conflict in a serial bus system (1). The conflict detector (15; 15A; 15B; 15C; 25; 35) has at least one counter (150; 152) for counting the occurrence of a property of pulses of a digital received signal (RxD; RxD1), which is generated by the subscriber station (10; 20; 30) from a signal (VDIFF) which is serially received from a bus (40) of the bus system (1), wherein the signal (VDIFF) received from the bus (40) was formed from a transmission signal (TxD; TxDI; TxD2) that was sent serially to the bus (40) from a communication control device (11) of the subscriber station (10; 20; 30) for a frame (450), and wherein, in a first communication phase (451; 453, 451), the subscriber station (10; 20; 30) generates bus states (401; 402) for the frame (450) by means of a first operating mode and, in a second communication phase (452), generates bus states (401; 402; U_D0; U_D1) for the frame (450) by means of a second operating mode, which differs from the first operating mode, and a comparison block (153; 153A; 153B; 153C), which is designed to compare a measurement result determined from a counted measurand (Zasym; Zrx) of the at least one counter (150; 152) to at least one threshold value (Ts) and, by means of a conflict indicator signal (S_K), to indicate for the communication control device (11) when the comparison block (153; 153A; 153B; 153C) determines in the comparison that the subscriber station (10; 20; 30) has no exclusive, collision-free access to the bus (40) in the second communication phase (452).

Description

description

Conflict detector for a subscriber station of a serial bus system and

Method for communication in a serial bus system

Technical area

The present invention relates to a conflict detector for a subscriber station of a serial bus system and a method for recognizing a bus conflict in a serial bus system that operates at a high data rate and with great error resistance.

State of the art

A bus system is often used for communication between sensors and control units, for example in vehicles, in which data is transmitted as messages in the ISO11898-l: 2015 standard as a CAN protocol specification with CAN FD. The messages are transmitted between the bus participants in the bus system, such as sensors, control units, transmitters, etc.

In order to be able to realize increasing data traffic in the bus system and / or a higher data transmission speed than with Classical CAN, an option for switching to a higher bit rate within a message was created in the CAN FD message format. With such techniques, the maximum possible data rate is increased by using a higher clock rate in the area of the data fields beyond a value of 1 Mbit / s. Such messages are also referred to below as CAN FD frames or CAN FD messages. With CAN FD, the maximum useful data length of 8 bytes for Classical CAN is extended to up to 64 bytes and the data transfer rates are significantly higher than for Classical CAN. Bus systems customary in the automotive sector use a differential two-wire bus line that distinguishes between two logical bit levels. With Classical CAN (ISO 11898-2) or CAN FD and LIN (ISOJ.7987-4) only one of the two logical bus levels is driven, the other is set via a terminating resistor on the bus line. As a result, the driven, dominant bus level can overwrite the non-driven, recessive bus level. This is used to ensure collision-free access to the bus line for a transmitter for a predetermined period of time by means of arbitration. According to another use, an error frame (error flag) can be sent on the bus in the event of an error. With the time-controlled FlexRay (ISO 17458-4), both logical bus levels are driven. These symmetrical bus levels allow a higher bit rate, but neither arbitration nor error frames as with Classical CAN / CAN FD.

Even if a Classical CAN or CAN FD based communication network offers many advantages with regard to, for example, its robustness, it still has a significantly lower bit rate compared to data transmission with, for example, 100 Base-Tl Ethernet. In addition, the user data length of up to 64 bytes previously achieved with CAN FD is too short for some applications.

In order to solve these problems, a CAN FD successor system is currently being developed, which is called CAN XL in the following. In the data phase of a CAN-XL frame, both bus states (0, 1) should be driven in order to achieve higher data rates.

If both bus states are actively driven in the data phase with CAN-XL, the sending of an error frame (error flag) leads to a superimposition of driven signals, which results in "analog" levels on the bus. As a result, the resulting RxD signal can no longer be precisely predicted and the Classical CAN / CAN FD method cannot be used with regard to error frames.

Disclosure of the invention It is therefore the object of the present invention to provide a conflict detector for a subscriber station of a serial bus system and a method for detecting a bus conflict in a serial bus system which solve the problems mentioned above. In particular, a conflict detector for a subscriber station of a serial bus system and a method for recognizing a bus conflict in a serial bus system are to be provided, in which a high data rate and a flexible reaction to current operating states as well as a high level of error robustness of the communication can be realized.

The object is achieved by a conflict detector for a subscriber station of a serial bus system with the features of claim 1. The conflict detector has at least one counter for counting the occurrence of a property of pulses of a digital received signal that is generated by the subscriber station from a signal received serially from a bus of the bus system, the signal received by the bus being formed from a transmission signal received by a communication control device of the subscriber station has been sent serially to the bus for a frame, and wherein the subscriber station generates bus states for the frame with a first operating mode in a first communication phase and generates bus states for the frame with a second operating mode in a second communication phase that differ from the first operating mode, and a comparison block for comparing the measurement result of the at least one counter with at least one threshold value and for displaying with a conflict display signal for the communication control device if the comparison block determines during the comparison, that the subscriber station does not have any exclusive, collision-free access to the bus in the second communication phase.

Due to the configuration of the conflict detector, even in the event that both bus states are actively driven in a frame in the data phase, the detection of a transmission conflict is very cost-effective. This also applies if there is a superposition of driven signals on the bus, whereby “analog” levels are set on the bus, so that the resulting received signal RXD can no longer be precisely predicted.

The recognition or detection of the bus conflict with the conflict detector, in particular in the communication control device (protocol controller), is very cost-effective because a lot of information is digitally available in the communication control device and a precise clock is available. Therefore, the bus conflict can be detected very precisely. In addition, the detection is easy to implement, namely for example by means of one or more counters. This simplifies and reduces the cost of a transmitting / receiving device (transceiver) for CAN XL, which favors the use of CAN XL.

Additionally or alternatively, the conflict detector is integrated into a transmitting / receiving device of the subscriber station.

In addition, it is possible that bus conflict detection can be used with currently available CAN transceivers.

Because of the configuration of the conflict detector, each subscriber station in the bus system is therefore able to disrupt or interrupt the transmission of any other subscriber station with an error frame. The error frames used implement simple error handling, which in turn increases the robustness of the CAN XL protocol. In addition, time can be saved in the event of an error by canceling a message currently being sent and then transferring other information on the bus. This is particularly useful for frames that are longer than a CAN FD frame with 64 bytes in the data phase, especially for frames that are to contain 2-4 KB or more.

As a result, the conflict detector can be used to ensure reception of the frames with great flexibility with regard to current events in the operation of the bus system and with a low error rate, even if the amount of user data per frame increases. Thus, in the serial bus system, can be communicated with great error resistance if there is a high data rate and an increase in the amount of user data per frame.

Therefore, with the conflict detector in the bus system, it is possible in particular to maintain an arbitration known from CAN in a first communication phase and nevertheless to increase the transmission rate again considerably compared to Classical CAN or CAN FD.

This helps to achieve a net data rate of at least 5 Mbit / s to around 8 Mbit / s or 10 Mbit / s or higher. In this case one bit is less than 100 ns long. In addition, the size of the user data can be up to 4096 bytes per frame. Of course, any other values are possible for the number of bytes per frame, in particular 2048 bytes or some other value.

The method carried out by the conflict detector can also be used if the bus system also has at least one CAN FD-tolerant CAN subscriber station, which is designed in accordance with the ISO 11898-1: 2015 standard, and / or at least one CAN FD subscriber station that send messages according to the Classical CAN protocol and / or CAN FD protocol. In principle, the conflict detector can also be used with CAN FD to replace or supplement the Transmitter Delay Compensation function used there.

Advantageous further refinements of the conflict detector are given in the dependent claims.

Possibly the property of pulses of the digital received signal is the level of the pulse, wherein the at least one counter can be designed to count the frequency of occurrence of a first level of the digital received signal over time. Alternatively, the at least one counter can be designed to increment its count value when a first level of the digital received signal occurs and to decrement its count value when the second level of the digital received signal occurs. The frequency of occurrence of a predetermined level can be adjusted with a predetermined timing to get voted. The resulting count can also be referred to as the accumulated duration.

It is conceivable that the property of pulses in the digital received signal is the pulse length of the pulse. In this case, the at least one counter (150; 152) and / or the comparison block can be designed to use a status signal of the communication control device to determine the property of pulses of the digital received signal that sets the clock for sampling bits of the digital received signal and / or comprises the clock of the communication control device. Alternatively, the comparison block can be designed to compare the pulse length of a pulse of the digital received signal with a pulse length of a pulse of the transmitted signal in order to determine whether the subscriber station does not have exclusive, collision-free access to the bus in the second communication phase.

According to another variant, the property of pulses in the digital received signal is the difference between the level of the pulse and the corresponding level of a pulse in the transmitted signal.

According to yet another variant, the conflict detector also has at least one additional counter for counting the occurrence of a property of pulses in the digital transmission signal, the comparison block being designed to compare a measurement result determined from the count of the at least one additional counter with at least one threshold value in order to to determine whether the subscriber station has no exclusive, collision-free access to the bus in the second communication phase. Here, the comparison block is designed according to an option to compare a count value of the at least one counter, which is provided for counting the occurrence of a property of pulses of the digital received signal, with a count value of the at least one additional counter, which is used to count the occurrence of a property of Pulsing of the digital transmission signal is provided in order to determine on the basis of a changing difference in the compared counted values whether the subscriber station does not have exclusive, collision-free access to the bus in the second communication phase. In the variants mentioned, the conflict detector can be configured to use a delayed transmission signal as the transmission signal, which is delayed by a transit time that the transmission signal needs to get from a TxD connection of the communication control device via the bus to an RxD connection of the communication control device .

The conflict detector also optionally has at least one counter for counting rising and / or falling edges of the pulses of the digital received signal or the transmitted signal.

The conflict detector described above can be part of a subscriber station for a serial bus system, which also has a communication control device for controlling communication of the subscriber station with at least one other subscriber station of the bus system, and a transmitting / receiving device for sending one of the

Communication control device for a frame generated signal on a bus of the bus system and for receiving a signal from the bus, wherein the transmitting / receiving device generates bus states for the frame with a first operating mode in a first communication phase and bus states for the frame with in a second communication phase a second operating mode, which differ from the first operating mode.

At the subscriber station, due to the different bit rates in the two communication phases, the bus states of the signal received from the bus in the first communication phase can be longer, in particular have a longer bit time, than the bus states of the signal received in the second communication phase. Additionally or alternatively, the bus states of the signal received from the bus in the first communication phase were generated with a different physical layer than the bus states of the signal received in the second communication phase. Here, the communication control device can be configured to output a switch-on signal to the conflict detector in order to switch the conflict detector on only for the second communication phase and to switch it off for the first communication phase, or to switch the conflict detector from one communication phase to another. It is possible that in the first communication phase it is negotiated which of the subscriber stations of the bus system is at least temporarily given exclusive, collision-free access to the bus in the subsequent second communication phase.

The subscriber station described above can be part of a bus system which also comprises a bus and at least two subscriber stations which are connected to one another via the bus in such a way that they can communicate with one another serially. In this case, at least one of the at least two subscriber stations is a previously described subscriber station.

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 conflict detector for a subscriber station of the serial bus system, the conflict detector carrying out the steps of counting, with at least one counter, the occurrence of a property of pulses of a digital received signal that is serialized by the subscriber station from a bus of the bus system received signal is generated, wherein the signal received by the bus was formed from a transmission signal that was sent serially to the bus by a communication control device of the subscriber station in a frame, and wherein the subscriber station in a first communication phase bus states for the frame with a first operating mode generated and, in a second communication phase, generated bus states for the frame with a second operating mode that differs from the first operating mode,

Compare, with a comparison block, a measurement result determined from a count of the at least one counter with at least one threshold value, and display with a conflict indication signal for the communication control device if the comparison block determines during the comparison that the subscriber station does not have exclusive, collision-free access in the second communication phase got on the bus.

The method offers the same advantages as mentioned above with regard to the conflict detector and / or the subscriber station. Further possible implementations of the invention also include combinations, not explicitly mentioned, of features or embodiments described above or below with regard to the exemplary embodiments. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

drawings

The invention is described in more detail below with reference to the accompanying drawings and using exemplary embodiments. Show it:

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

2 shows a diagram to illustrate the structure of messages that can be sent by a transmitting / receiving device for a subscriber station of the bus system according to the first exemplary embodiment;

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

FIGS. 4 to 7 show a time profile of signals that occur in normal operation in the bus system according to the first exemplary embodiment;

8 shows a time profile of a transmission signal TxD1 in a data phase of a message which is sent by a first subscriber station of the bus system according to the first exemplary embodiment;

FIG. 9 shows a time profile of a transmission signal TxD2 which is sent by another subscriber station in order to abort the transmission signal TxD1 from FIG. 8; FIG. FIGS. 10 to 12 show a time profile of signals which arise on the basis of the transmit signals TxD1, TxD2 from FIGS. 8 and 9 in the bus system according to the first exemplary embodiment;

13 shows a diagram to illustrate the function of a conflict detector of a subscriber station of the bus system according to the first exemplary embodiment;

14 shows a simplified schematic block diagram of a subscriber station of the bus system according to a second exemplary embodiment;

15 shows a simplified schematic block diagram of a subscriber station of the bus system according to a third exemplary embodiment;

16 shows an example of signal curves to illustrate the mode of operation of a conflict detector of the subscriber station of the bus system according to the third exemplary embodiment;

17 shows a simplified schematic block diagram of a subscriber station of the bus system according to a fourth exemplary embodiment; and

18 shows an example of signal profiles to illustrate the mode of operation of a conflict detector of the subscriber station of the bus system according to the fourth exemplary embodiment.

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

Description of the exemplary embodiments

As an example, FIG. 1 shows a bus system 1 which, in particular, is fundamentally designed for a Classical CAN bus system, a CAN FD bus system, a CAN XL bus system and / or modifications thereof, as described below. The bus system 1 can be used in a vehicle, in particular a motor vehicle, an airplane, etc., or in a hospital, etc. use. In FIG. 1, the bus system 1 has a multiplicity of subscriber stations 10, 20, 30, each of which is connected to a bus 40 with a first bus core 41 and a second bus core 42. The bus wires 41, 42 can also be called CAN_H and CAN_L or CAN-XL_H and CAN-XL_L and are used for electrical signal transmission after coupling in the difference level or dominant level or generating recessive levels for a signal in the transmission state. Messages 45, 46 in the form of signals between the individual subscriber stations 10, 20, 30 can be transmitted serially via bus 40. If an error occurs in communication on bus 40, as shown by the jagged black block arrow in FIG. 1, an error frame 47 (error flag) can be sent. The subscriber stations 10, 20, 30 are, for example, control devices, sensors, display devices, etc. of a motor vehicle.

As shown in Fig. 1, the subscriber station 10 has a

Communication control device 11, a transmitting / receiving device 12 and a conflict detector 15. The subscriber station 20, on the other hand, has a communication control device 21, a transmitting / receiving device 22 and optionally a conflict detector 25. Subscriber station 30 has a communication control device 31, a transmitting / receiving device 32 and a conflict detector 35. The transmitting / receiving devices 12, 22, 32 of the subscriber stations 10, 20, 30 are each connected directly to the bus 40, even if this is not illustrated in FIG.

The communication control devices 11, 21, 31 each serve to control communication between 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.

The communication control device 11 creates and reads first messages 45, which are modified CAN messages 45, for example. Here, the modified CAN messages 45 are structured on the basis of a CAN XL format, which is described in more detail with reference to FIG. 2. The communication control device 21 can be designed like a conventional CAN controller according to ISO 11898-1: 2015 apart from the differences described in more detail below. The communication control device 21 creates and reads second messages 46, for example Classical CAN messages 46. The Classical CAN messages 46 are structured in accordance with the Classical basic format, in which the message 46 can contain up to 8 data bytes. Alternatively, the CAN message 46 is structured as a CAN FD message, in which a number of up to 64 data bytes can be included, which are also transmitted at a significantly faster data rate than in the case of the Classical CAN message 46. In the latter case, the communication control device 21 is designed like a conventional CAN FD controller.

The communication control device 31 can be designed to provide a CAN XL message 45 or a Classical CAN message 46 for the transmitting / receiving device 32 or to receive it from it, as required. The communication control device 31 thus creates and reads a first message 45 or second message 46, the first and second messages 45, 46 differing in their data transmission standard, namely in this case CAN XL or CAN. Alternatively, the Classical CAN message 46 is structured as a CAN FD message. In the latter case, the communication control device 31 is designed like a conventional CAN FD controller.

The transmitting / receiving device 12 can be designed as a CAN XL transceiver. The transmitting / receiving device 22 can be designed like a conventional CAN transceiver or CAN FD transceiver. The transmitting / receiving device 32 can be designed to provide messages 45 according to the CAN XL format or messages 46 according to the current CAN basic format for the communication control device 31 or to receive them from it, as required. The transmitting / receiving devices 12, 32 can additionally or alternatively be designed like a conventional CAN FD transceiver. With the two subscriber stations 10, 30, the formation and then transmission of messages 45 with the CAN XL format and the receipt of such messages 45 can be implemented.

FIG. 2 shows a CAN XL frame 450 for the message 45, as it is 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 453 for the CAN communication on the bus 40, namely an arbitration phase 451, a data phase 452 and a frame end phase 453.

In the arbitration phase 451, an identifier is used to negotiate bit by bit between the subscriber stations 10, 20, 30 which subscriber station 10, 20, 30 would like to send the message 45, 46 with the highest priority and therefore for the next time to send in the subsequent data phase 452 gets exclusive access to bus 40 of bus system 1.

In the data phase 452 the user data of the CAN-XL frame or the message 45 are sent. The useful data can have, for example, up to 4096 bytes or a larger value in accordance with the value range of a data length code.

The frame end phase 453 can contain a reintegration pattern that enables the receiving subscriber stations to find the start of the frame end phase 453 after an error. In addition, at least one acknowledge bit can be contained in an end field in the frame end phase 453. In addition, there can be a sequence of 11 identical bits, which indicate the end of the CAN XL frame 450. The at least one acknowledge bit can be used to indicate whether a recipient has discovered an error in the received CAN XL frame 450 or message 45 or not.

In the arbitration phase 451 and the frame end phase 453, a physical layer is used as in Classical CAN and CAN-FD. The physical layer corresponds to the physical layer or layer 1 of the known OSI model (Open Systems Interconnection Model).

During phases 451, 453, the known CSMA / CR method is used, which allows subscriber stations 10, 20, 30 to access bus 40 at the same time without the higher-priority message 45, 46 being destroyed. As a result, further bus subscriber stations 10, 20, 30 can be added to bus system 1 relatively easily, which is very advantageous.

The consequence of the CSMA / CR method is that there must be so-called recessive states on the bus 40, which other subscriber stations 10, 20,

30 can be overwritten with dominant states on bus 40. In the recessive state, high-resistance conditions prevail at the individual subscriber stations 10, 20, 30, which in combination with the parasites of the bus circuit results in longer time constants. This leads to a limitation of the maximum bit rate of today's CAN FD physical layer to currently around 2 megabits per second in real vehicle use.

A sender of the message 45 does not begin sending bits of the data phase 452 on the bus 40 until the subscriber station 10 as the sender has won the arbitration and the subscriber station 10 as the sender thus has exclusive access to the bus 40 of the bus system 1 for sending .

In general, the following different properties can be implemented in the bus system with CAN XL compared to Classical CAN or CAN FD: a) Adoption and, if necessary, adaptation of proven properties that are responsible for the robustness and user-friendliness of Classical CAN and CAN FD, in particular the frame structure with identifier and arbitration according to the CSMA / CR method, b) increase the net data transmission rate to about 10 megabits per second, c) increase the size of the useful data per frame to any length, for example up to about 4 kbytes.

3 shows the basic structure of the subscriber station 10 with the communication control device 11, the transmitting / receiving device 12 and the conflict detector 15. The subscriber station 30 is similar constructed as shown in FIG. 3, except that the conflict detector 35 is not integrated in the communication control device 31, but is provided separately from the communication control device 31 and the transceiver 32. In the subscriber station 20, the optionally present conflict detector 25 is integrated into the transmitting / receiving device 22. The subscriber stations 20, 30 and the devices 25, 35 are therefore not described separately. The functions of the conflict detector 15 described below are identical in each of the conflict detectors 25, 35.

According to FIG. 3, the subscriber station 10 has, in addition to the conflict detector 15 in the communication control device 11, a send / receive block 111. The send / receive block 111 is a protocol controller that sends the send signal TxD according to the protocol for a frame 450, for example for a message 45 or for a frame for a message 46 and forwards the transmission signal TxD to the transmitting / receiving device 12 and taking it over from the transmitting / receiving device 12 to receive a received signal RxD. The transmitting / receiving device 12 is connected to the bus 40, more precisely its first bus core 41 for CAN_H or CAN-XL_H and its second bus core 42 for CAN_L or CAN-XL_L. For a frame 450, the transmission signal TxD is converted by the transmitting / receiving device 12 into signals CAN-XL_H, CAN-XL_L for the bus 40, as described above. The RxD signal is generated as also previously described.

The conflict detector 15 has a first counter 151, a second counter 152, a comparison block 153 and an optional compensation block 154. The conflict detector 15 detects the signals RxD and TxD in order to detect a conflict on the bus 40. As a result, the conflict detector 15 supplies a conflict indication signal S_K in order to signal whether or not there is a conflict on the bus 40. If the conflict indication signal S_K has the value 1, for example, if a conflict was detected, the send / receive block 111 will then send an error frame 47 to the bus 40 instead of continuing with the frame 450 sent up to then. In addition, the send / receive block 111 optionally sends an enable signal or a switch-on signal S_E to the conflict detector 15 if the conflict detector 15 is only to work during a valid sending process.

The send / receive block 111 can optionally send a status signal S_l to the conflict detector 15. The status signal S_l contains that information which the send / receive block 111 provides to the conflict detector 15, for example a transit time TLD for the compensation block 154, which is described in more detail with reference to FIG.

The conflict detector 15 of FIG. 3 works with the CAN clock, which corresponds to the clock of the communication control device 11, in particular the CAN XL protocol controller. Due to its relatively high frequency, the CAN clock enables precise detection of deviations in the signals RxD, TxD. Additionally or alternatively, a time quantum clock can be used which is used by the send / receive block 111. The time quantum cycle is a divided CAN cycle. A user can set the division ratio with the so-called bit rate prescaler parameter in the CAN XL controller.

The more precise function of the conflict detector 15 is described in more detail below after explaining the signals in the bus system 1 according to FIGS. 4 to 12.

4 to 7 illustrate signals during normal operation of the bus system 1. In the course of time t, the transmitting / receiving device 12 sets a transmit signal TXD or TxD of the communication control device 11 according to FIG. 4 into corresponding signals CAN-XL_H and CAN-XL_L for the bus wires 41, 42 and sends these signals CAN-XL_H and CAN-XL_L to the connections for CAN_H and CAN_L on the bus 40, as shown in FIG. From the signals CAN-XL_H and CAN-XL_L from FIG. 5, a differential voltage VDIFF = CAN-XL_H - CAN-XL_L is formed on bus 40 over time t, the course of which is shown in FIG.

With the exception of an idle or standby state (idle or standby), the transmitting / receiving device 12 always listens to one in normal operation Transmission of data or messages 45, 46 on the bus 40, regardless of whether the transmitting / receiving device 12 is the sender of the message 45 or not. The transmitting / receiving device 12 forms a received signal RXD or RxD from signals CAN-XL_H and CAN-XL_L received from bus 40 with reception thresholds T_u, T_d according to FIG. 6, as shown in FIG. 7 over time t. For the phases 451, 453, at least one reception threshold T_u is used, which is in the hatched area in the left part of FIG. 6. As shown in FIG. 6, in the communication phases 451, 453 the transceiver 12 uses the first reception threshold T_u known from Classical CAN / CAN-FD with the typical position of 0.7 V according to ISO11898-2: 2016 to be able to reliably recognize the bus states 401, 402 in the first operating mode. In contrast, for the data phase 452, a switch is made to at least one reception threshold T_d, which is located in the hatched area in the right-hand part of FIG. The transmitting / receiving device 12 forwards the received signal RXD or RxD to the communication control device 11, as shown in FIG. 3.

According to the example of FIGS. 4 and 5, the signals CAN-XL_H and CAN-XL_L have the dominant and recessive bus levels 401, 402 in the aforementioned communication phases 451, 453 corresponding to the states H, L of the transmission signal TxD from FIG. 4 as known from CAN. In contrast, the signals CAN-XL_H and CAN-XL_L differ in the data phase 452 from the conventional signals CAN_H and CAN_L. In the data phase 452, instead of the bus levels 401, 402, the bus levels U_D1, U_D0 are now actively driven in accordance with the data states H, L of the transmission signal TXD. The difference signal VDIFF = CAN-XL_H - CAN-XL_L is formed on bus 40, as shown in FIG. 6.

In addition, a switch is made from a first bit time T_btl in phases 451, 453 to a second bit time T_bt2 in phase 452. The first bit time T_btl is greater than the second bit time T_bt2, even if this is not shown in FIGS. 4 to 7 for the sake of simplicity. The bits of the signals are therefore transmitted more slowly in phases 451, 453 than in data phase 452. With a bit rate of, for example, 10Mbil / s in data phase 452, the second bit time T bt2 has the value 100 ns. Thus, the bit duration T_bt2 in the data phase 452 in the example shown in FIGS. 4 and 5 is significantly shorter than the bit duration T_btl that is used in the arbitration phase 451 and the frame end phase 453.

Thus, the transceiver 12 is switched from the state that is shown in the left part of FIG. 4 for the data phase 452 to the state that is shown in the right part of FIG. The transmitting / receiving device 12 is thus switched from a first operating mode to a second operating mode.

The sequence of the data states H, L from FIG. 4 and thus the resulting bus states U_D0, U_D1 for the signals CAN-XL_H, CAN-XL_L in FIG. 5 and the resulting profile of the voltage VDIFF from FIG. 6 are only used for illustration the function of the transmitting / receiving device 12. The sequence of the data states H, L from FIG. 4 and thus the resulting bus states U_D0, U_D1 in FIG. 5 can be selected as required.

For the data phase 452, FIGS. 8 to 12 show a signal profile of the signals TxDl, TxD2, CAN-XL_H and CAN-XL_L, their differential voltage VDIFF = CAN-XL_H-CAN-XL_L and the resulting received signal RxD. In the case shown in FIGS. 8 to 12, for example, the transmitting / receiving device 12 sends the transmission signal TxD1 for a frame 450, whereby, for example, the subscriber station 30, which is actually only the recipient of the frame 450 in the data phase 452, is aborted of the frame 450 wants to reach and therefore sends the transmit signal TxD2.

There are various reasons why frame 450 should be aborted:

- The subscriber station 30 as an RX subscriber station has found an error in the header checksum (CRC = Cyclic Redundancy Check) of the CAN XL message 45, and would like to signal this, and / or

The subscriber station 20, which is a CAN FD subscriber station, may have to switch to the format of the frame 450 due to a bit error not recognized and sends an error frame 47 during the data phase 452 of the frame 450, and / or

the subscriber station 30 as an RX subscriber station has to send a message 45, 46 with a higher priority, and / or

- Two CAN-XL subscriber stations, for example the subscriber stations 10, 30 inadvertently use the same identifier and thus both send in the data phase 452.

If, for example, the subscriber station 30 would like to abort the frame 450 which the transmitting / receiving device 12 sends with the signal TxDl of FIG. 8, the subscriber station 30 sends the transmit signal TxD2 according to FIG. 9 to the bus 40. In phase 455 of the Sending the error frame 47, which begins with the falling edge of the transmission signal TxD2 at a point in time t2, therefore results in voltage states on the bus 40 according to FIGS. 10 and 11 which deviate from the voltage states on the bus 40 during normal operation of the data phase 452 .

In general, the sending subscriber station that sends the send signal TxD1 switches to a send operating mode in the data phase 452 for driving the bus lines 41, 42. In contrast, the at least one reception threshold Td shown in FIG. 11 is switched on for all receiving subscriber stations, such as subscriber station 30. Here, however, the bus driver of the receiving subscriber station 30 remains in the passive receiving state (CAN recessive state) until the receiving subscriber station 30 possibly sends the error frame 47, as shown in FIG. 9 for the transmit signal TxD2 and mentioned above. The error frame 47 according to the right-hand part of FIG. 7 will then be actively sent as "dominant". In order to enable the interoperability of CAN-XL and CAN-FD, an error frame 47 is represented by the stringing together of 6 or more (depending on the bit stuffing method) bits with positive VDIFF, as was the case with CAN / CAN-FD.

If, in the case described above, an error frame 47 is sent by subscriber station 30, the transient course of the differential voltage VDIFF changes very sharply in the sequence shown in FIG. 11. From everyone's point of view Subscriber stations 10, 20, 30, a bit with a positive differential voltage VDIFF, that is to say the bus state U_D1, is further amplified or the positive differential voltage VDIFF is increased. In contrast, a bit that is formed as the bus state U_D0 on the bus 40 is increased from the differential voltage VDIFF = -2 V to a differential voltage VDIFF of approximately 0V. The resulting voltage value for the bus state U_D0 depends heavily on the parameters of the driving transceiver devices 12, 22, 32 or of the transmitter 121, as well as the arrangement of the terminating resistors.

As shown schematically in FIG. 12 with an ellipse 60, this can result in an unrecognized 1-pulse in the received signal RxD. It is also possible for a 1-pulse at the RxD connection and thus in the received signal RxD to be shortened, as marked with an ellipse 65 in FIG. 12. In addition to the illustration in FIG. 12, the differential voltage VDIFF is in the real case still superimposed by high-frequency oscillations which are determined by the bus topology, phase position and impedance of the subscriber station that sends the error frame 47. Shortened or lengthened 1-plus (or 0-pulses) cannot be recognized in most cases by a TDC method known from CAN FD (TDC = Transmitter Delay Compensation = delay compensation of the transmitting / receiving device).

Even if the error detection can be improved by adding further reception thresholds in the transmitting / receiving device 12, there are, however, signal profiles which can no longer be detected as errors even as a result.

According to FIG. 3, the conflict detector 15 in the subscriber station 10 has the counters 151, 152 and the comparison block 153 for the detection of a transmission conflict which causes the bus conflict according to FIG. 11. In the transmission conflict, the subscriber station 10 does not have an exclusive one in the data phase 452 , more collision-free access to bus 40.

The conflict detector 15 detects the signals RxD and TxD using the two counters 151, 152. Here, the counter 151 is used to evaluate the transmission signal TxD, the counter 151 its count value Ztx changed. The counter 152 is used to evaluate the received signal RxD, the counter 152 changing its count value Zrx. The counters 151, 152 each count not only the number of levels in the signals TxD, RxD under consideration. Instead, the counters 151, 152 each also count the accumulated duration of the occurrence over the time t with a clock, in particular the CAN clock. The CAN clock is present in the communication control device 11 and is forwarded to the conflict detector 15 with the status signal S_l.

The send / receive block 111 sets the enable signal or switch-on signal S_E to 1 at the beginning of the data phase 452, that is to say at time t 1, in order to start the conflict detection with the conflict detector 15. Since the delayed TxDl signal TxDl_d is used in this exemplary embodiment, the enable signal S_E is also set to 1, delayed by the duration or transit time TLD, as illustrated in FIG. With the edge of the switch-on signal S_E, the count values Ztx, Zrx of the counters 151, 152 are reset to zero.

The conflict detector 15 compares the signals RxD, TxD with one another in order to detect a bus conflict. To do this, it continuously determines the duration of the occurrence of one of the bus levels (0 or 1) in the data phase 452 of a frame 450 on the RxD and on the TxD signal. The count value Ztx of the counter 151 is incremented by 1 once per clock period when the transmission signal TxD has a value H, for example when TxD = 1, as shown in FIG. The count value Zrx of the counter 152 is incremented by 1 when the received signal RxD has a value H, for example when RxD = 1, as shown in FIG. If, for example, the level of the RxD signal is at the value H for the duration of 40 clock periods, the counter Zrx is incremented by 40 during this time. Alternatively, the counters 151, 152 can increase their count value Ztx, Zrx if the states TxD = 0 and RxD = 0 of the signals TxD, RxD respectively observed by the counters 151, 152 are detected.

The duration of the occurrence of one of the bus levels (0 or 1) determined by the conflict detector 15 is thus the frequency of occurrence of a predetermined level. The duration is thus counted with a predetermined cycle, in particular the CAN cycle, which is the cycle of the communication control device 11 is. The count value Ztx, Zrx resulting from the count can also be referred to as the accumulated duration, as described above.

The bus conflict can be derived from the comparison of the measurements of the counters 151, 152 for the signals TxD and RxD with the comparison block 153. For this purpose, the comparison block 153 forms a difference D = Ztx − Zrx as a measurement result, as illustrated in FIG. 13. Here, the conflict detector 15 takes into account that the TxD signal is ideal, but the RxD signal is not ideal even in a conflict-free case, that is to say it is different from the TxD signal.

To detect a conflict, the comparison block 153 must regularly form and evaluate the difference D between the count values Ztx, Zrx of the counters 151, 152. Regularly means, for example, 1 time per bit time T_bt2 or 1 time per 5 bit times T_bt2. In simplified terms, if the difference D increases (or decreases) sharply, then there is a bus conflict. The change between the currently formed difference D and the last difference D formed is referred to as DeltaD.

If DeltaD exceeds or significantly exceeds a threshold Ts, which can also be referred to as DeltaDiffRef, then the asymmetry is greater than in normal operation and there is most likely a bus conflict. The threshold Ts can be set in various ways. For example, DeltaD can be measured during normal operation, especially in the first successfully transmitted frame. Alternatively, DeltaD can be measured continuously with every successfully sent frame. For example, if a DeltaD = +2 is measured in the error-free case, the difference D per bit time T_bt2 increases by 2 if a bit with the value TxD = 1 is sent. The threshold Ts can then be defined, for example, as “DeltaD measured in the error-free case” + 2, that is to say, in the example mentioned, as Ts = 2 + 2 = 4.

Alternatively, the threshold Ts can be specified initially. If, for example, the difference change DeltaD is determined once per bit time T_bt2, then a possible value for the threshold Ts is, for example, half a bit time T_bt2. Thus, if a sent bit is 20 CAN clock periods long, then a threshold Ts = 10. 13 shows a specific example of a course of the counter values Ztx, Zrx for the course of the signal TxD2 with which the error frame 47 is sent, the delayed transmission signal TxDl_d and the resulting signal RxDl. In the example shown, it is assumed that, without a bus conflict, the received signal RxD1 is also ideal in order to simplify the picture. In reality, the RxDl signal will be slightly asymmetrical in normal operation (without bus conflict), i.e. the 1 bits are slightly longer than the 0 bits, or vice versa. This has the consequence that the two counters Ztx and Zrx slowly diverge. The RxDl signal is delayed due to the transit time TLD via the bus 40, more precisely from the TxD connection of the sending subscriber station to the RxD connection of the same sending subscriber station, by the transit time TLD compared to the TxD signal. Each bit has the bit time T_bt2. In the time period T_K the conflict arises or exists on the bus 40, since the threshold Ts shown schematically is exceeded.

In the event of a bus conflict, the bit asymmetry is increased. In the example of FIG. 13, this leads to the 1 level on bus 40 being shortened. The count value Zrx of the counter 152 thus increases more slowly than the count value Ztx of the counter 151 in the period T_K.

For faster and more accurate detection of a conflict, that is to say optionally, the conflict detector 15 compensates for the transit time TLD from the TxD signal via the transceiver to the RxD signal with the compensation block 154. The compensation block 154 uses a clock, in particular the CAN clock and / or the clock for sampling bits of the digital received signal and / or another clock that can be provided by the communication control device 11 via the status signal S_l. The TLD runtime can also be referred to as Transmitter Loop Delay (TLD). If the runtime TLD is not taken into account and compensated, the difference between the two counters Ztx and Zrx must be evaluated more tolerantly. In particular, the threshold Ts for detection of a bus conflict must be greater than the value of the difference D by which one of the counters 151, 152 can change during the time TLD.

For the compensation, the send / receive block 111 measures the transit time TLD. This can be done, for example, on the first rising or falling edge in the Data phase 452 occur. The TLD runtime is measured in the same way as it is necessary for the TDC function with CAN FD. The send / receive block 111 provides the conflict detector 15 with the measured transit time TLD as information about the status signal S_l.

As a result, the conflict detector 15 with the compensation block 154 can delay the TxD signal sent by the send / receive block 111 instead of processing the TxD signal directly. The conflict detector 15 thus considers the signal TxD_d, as shown in the upper part of FIG. In addition, the switch-on signal S_E is generated after the start of the data phase 452 delayed by the runtime TLD. The RxD signal is thus analyzed by the conflict detector 15 only from the point in time from which the RxD signal is valid. 13 shows the received signal RxDl, which is generated by the subscriber station 10 in the aforementioned example, in which the subscriber station 10 sends the transmit signal TxD1 and the subscriber station 30 would like to abort the transmit signal TxD1 with a transmit signal TxD2.

The compensation block 154 can be designed as a shift register. Alternatively, and in a much more resource-saving manner, the compensation block 154 can be configured as a state machine. This is possible because the subscriber station acting as the transmitter knows how many CAN clock periods or time quanta (TimeQuanta) a transmitted bit consists of.

The communication control device 11 reacts in the data phase 452 to the signaled transmission conflict or bus conflict by aborting the data phase 452 and, if necessary, also by sending a bit pattern, for example an error frame 47, which signals the end of the data phase 452 to the other subscriber stations 20, 30. The communication control device 11 switches back to the arbitration phase 451.

At the subscriber stations 20, 30, the conflict can be signaled in the data phase 452 by a signal from the respective transceiver 22, 32 to the associated

Communication control device 21, 32 take place. The signal can do that The reception signal RXD, which the corresponding transceiver 22 or the conflict detector 35 modifies with a predetermined bit pattern in order to signal the conflict. Alternatively or additionally, the corresponding transmitting / receiving device 22, 32 or the conflict detector 25, 35 can generate a separate signal that is sent via a separate signal line to the associated communication control device 21, 31 and in particular at least one switching pulse or a predetermined bit pattern for signaling the Has conflict.

Because the send conflict or bus conflict is signaled to the associated communication control device 11, 21, 31 in data phase 452, the bit error check conventional in classic CAN can be replaced by comparing the send signal TXD with the receive signal RXD by checking the conflict indication signal S_K. The conflict indication signal S_K has, in particular, a predetermined bit pattern which signals or indicates the transmission conflict or bus conflict. In particular, the conflict indication signal S_K can send a T as an "OK signal" and an 'O' as a "conflict message".

It is optional in the embodiments of the detectors 15, 25, 35 described above that edges of at least one of the signals TxD, RxD can also be recognized and counted. There can be at least one additional counter for this. If more than one edge is counted per bit, this indicates an error. The conflict detector 15, 25, 35 can, for example, immediately report such an event as a bus conflict with the signal S_K. Alternatively, such an event can be recorded by additionally incrementing the count value by a predetermined value, e.g. Zrx: = Zrx + 1/2 bit time T_b2.

Optionally, in the embodiments of the detectors 15, 25, 35 described above, the counters 151, 152 could count both bus levels instead of just counting one bus level. In such a case, for example, the counter 151 could increment the count value Ztx at level 1 and decrement the count value Ztx at level 0. What is particularly advantageous about the variants of the evaluation described above is that the design of the transmitting / receiving device 12 is used both for homogeneous CAN-XL bus systems in which only CAN XL messages 45 and no CAN FD messages 46 are sent, and for mixed bus systems can be used in which either CAN XL messages 45 or CAN FD messages 46 are sent. The transmitting / receiving device 12 can therefore be used universally.

14 illustrates a configuration of a conflict detector 15A according to a second embodiment. The conflict detector 15A and the communication control device 11 according to the present exemplary embodiment are designed like the conflict detector 15 and the communication control device 11 according to the preceding exemplary embodiment, apart from the differences described below.

The conflict detector 15A performs an accumulated bit asymmetry measurement. For this purpose, the conflict detector 15A has only one counter 150 which measures or counts the difference between the RxD signal and the TxD signal. The counter 150 is incremented when the signal RxD and the TxD signal delayed by the transit time TLD are different. The counter 150 of the detector 15A thus counts the difference, that is to say the bit asymmetry, between RxD and TxD. At high bit rates of, for example, 5 Mbit / s or more, it is very advantageous if the RxD signal is compared with the delayed, i.e. compensated TxD signal. The compensation block 154 takes over the delay of the TxD signal. This variant is similar to the variant carried out by the conflict detector 15 according to the preceding exemplary embodiment.

As in the previous embodiment, the counter 150 is reset to zero with the edge of the switch-on signal S_E and then uses the CAN clock and / or time quantum clock to count the differences between the RxD signal and the TxD signal delayed by the time TLD . In addition, a count value Zasym of the counter 150 is evaluated at regular intervals, for example once per bit time, as described with reference to the preceding exemplary embodiment. If the change in the If the counter value Zasym exceeds a threshold value as the measurement result, then there is a large asymmetry and a bus conflict is recognized. The conflict detector 15A signals the bus conflict with the signal S_K.

In order to be able to evaluate the change in the count value Zasym more easily, the count value Zasym can be reset with the frequency of the evaluation. If the count value Zasym is evaluated, for example, once per bit time T_bt2, the counter 150 can also be reset during the evaluation. This has the advantage that the change in the count value Zasym corresponds exactly to the value of the count value Zasym, because the count always starts again at 0. The disadvantage of such a reset is that the history is lost.

15 illustrates a configuration of a conflict detector 15B according to a third embodiment. The conflict detector 15B and the communication control device 11 according to the present exemplary embodiment are configured like the conflict detector 15 and FIG. 4, except for the differences described below

Communication control device 11 according to the first embodiment.

The conflict detector 15B measures pulse lengths in the RxD signal. For this purpose, the conflict detector 15B has the counter 152 with which the conflict detector 15B continuously measures the pulse lengths in the RxD signal. A conflict can be derived using a comparison block 153B from the comparison of the pulse lengths as the measurement result with threshold values Ts.

16 shows examples of different pulse lengths TI, T2, T3 in the RxDl signal of the subscriber station 10, which is shown in comparison to the delayed transmission signal TxDl_d over time t. The pulse lengths TI, T2, T3 depend on the transmitted bit pattern in the transmission signal TxDl. The conflict detector 15B assumes that in the event of a bus conflict, the bit asymmetry in the RxD1 signal increases sharply. The conflict detector 15B thus detects a bus conflict when the 1-pulse or 1-phase is significantly shortened in the RxDl signal. This is the case, for example, for the pulse lengths TI, T3 of the 1-pulse of the RxD1 signal from FIG. To determine the pulse lengths TI, T2, T3 in the RxDl signal, the counter 152 counts the 1-pulses and 0-pulses of the RxDl signal. A pulse corresponds to a constant signal value that is limited by 2 edges. In FIG. 16, the RxDl signal has two 1-pulses, which have the different pulse lengths TI, T3, and a 0_pulse with the pulse length T2.

The conflict detector 15B, in particular its comparison block 153B, receives the sampling point clock with which the individual bits of the RxD1 signal are sampled by the send / receive block 111 via the status signal S_l.

The conflict detector 15B, in particular its comparison block 153B, is thus provided with the information about the number of bits scanned. As a result, the conflict detector 15B, in particular its comparison block 153B, knows how many bits the current pulse corresponds to, the pulse length of which TI, T2, T3 was measured by the counter 152.

To detect a conflict, the comparison block 153B compares the respectively measured pulse length TI, T2, T3 with at least one threshold value Ts. The at least one threshold value Ts of FIG. 16 indicates how short a pulse may be from which a conflict is recognized. For example, half a bit time T_b2 is a possible value. Alternatively or additionally, a threshold value Ts that is longer than a bit time T_b2 can be used. In such a case, the threshold value Ts indicates how long a pulse may be after which a conflict is recognized. Thus, instead of a shortening of the pulse lengths of the pulses in the RxDl signal, an extension of the pulse lengths of the pulses in the RxDl signal is sought.

For example, a threshold value Ts can be specified for each bit sequence with a constant value. If every S-th bit is a fixed stuff bit, then there are 2 * S bit sequences: 0, 00, 000, ..., S times 0; 1, 11, 111, ..., S times 1. That means 2 * S threshold values are required.

Alternatively, the threshold value Ts can be specified as the permitted shortening or lengthening of a pulse. For example, the permitted shortening or lengthening is half a bit time T_b2. Thus, the threshold value Ts at the pulse length T3, which corresponds to two bits in the example of FIG. 16, is 1.5 bit times. Since the length of a bit time T_b2 is available as information in CAN clock periods, the threshold value Ts can be determined very easily dynamically for each bit sequence. This has the great advantage that only one threshold value Ts has to be set.

A simplified evaluation with the comparison block 153B consists in looking for pulses that are too short. For example, the comparison block 153B is set in such a way that a pulse is evaluated as a pulse that is too short if a pulse is shorter than half a bit time T_b2, for example. This variant is very simple because only one comparison value or threshold value Ts is necessary. In the case of unfavorable bit sequences, however, it could be that this pulse length is not undershot despite the bus conflict.

The at least one threshold value Ts can be established in various ways. In particular, the threshold value Ts can be configured in a fixed manner. Alternatively or additionally, the threshold value Ts can be measured during normal operation, for example in the first successfully transmitted frame 450 or continuously with each successfully transmitted frame 450, or it can be a combination thereof.

The advantage of the function of the conflict detector 15B is that the variant is very easy to implement, since only the RxD signal is analyzed. In addition, in particular at the same time, the method carried out by the conflict detector 15B is able to evaluate / analyze any arbitrary bit sequence that is received at the RxD connection of the communication control device 11.

According to a first modification of the conflict detector 15B, the conflict detector 15B determines impermissibly long pulse lengths in the RxD signal in order to detect missing fixed stuff bits. In the case of CAN XL, the communication control device 11 uses fixed stuff bits or other fixed, recurring bit patterns for the synchronization in the data phase 452.

The conflict detector 15B, more precisely its comparison block 153, evaluates an impermissibly long pulse length as a bus conflict or another error. For example, if every S-th bit is a fixed stuff bit, then the maximum is allowed Pulse length TI, T2, T3 with a constant level has a value of S bits. The bit following this bit sequence is a fixed stuff bit with the inverse value of the S-th bit.

The counter 152 is thus also used in the modification of the conflict detector 15B in order to measure the pulse lengths between two edges. If a pulse length of, for example, S + 1 ideal bit lengths or bit times T_b2 or S + 0.8 ideal bit lengths or bit times T_b2 is measured, a fixed stuff bit is missing. In this case, the conflict detector 15B, more precisely its comparison block 153B, decides that there is a bus conflict. The conflict detector 15B, more precisely its comparison block 153B, reports the bus conflict to the communication control device 11 via the conflict indication signal S_K.

In addition to the aforementioned advantage of the conflict detector 15B, the advantage of the described first modification of the conflict detector 15B is that the parameter S is a CAN XL property. Therefore, no configuration is required for the modified conflict detector 15B to function. However, according to the first modification, the conflict detector 15B only detects missing bits in the data stream of the RXD signal. The modified conflict detector 15B cannot detect slight changes in the bit asymmetry.

However, if a bus system 1 only uses transceivers or transmitting / receiving devices 12, 22, 32 CAN XL exclusively in the arbitration mode, that is to say with recessive and dominant bus levels, then this type of conflict detection is sufficient. The reason for this is that the error frame 47 is sent dominantly and can therefore overwrite the send signal of the sending subscriber station.

According to a second modification of the conflict detector 15B, the conflict detector 15B compares the pulse lengths of a 1 pulse and a 0 pulse in the RxD signal in order to carry out a bit asymmetry measurement between two rising or two falling edges on the RxD signal.

For example, in the case of the bit sequence of FIG. 16, the bit asymmetry between two rising edges can be measured. As mentioned earlier, in that RxDl signal, the first 1-phase or the first 1-pulse has a pulse length TI and the first 0-phase or the first 0-pulse has a pulse length T2. Due to the fixed stuff bits, an O phase or a 1 phase can be between 1 and S bits long. Overall, there are S * S bit sequences made up of possible 0-phases and 1-phases.

The conflict detector 15B, more precisely its comparison block 153B, in the present second modification thus determines the asymmetry, for example, from the duration or pulse length TI of the 1-phase and the duration or pulse length T2 of the 0-phase and the number of bits per phase. If the bit asymmetry exceeds a threshold value, the conflict detector 15B, more precisely its comparison block 153B, detects a bus conflict. The conflict detector 15B, more precisely its comparison block 153B, reports the bus conflict to the communication control device 11 via the conflict indication signal S_K.

The advantage of the second modification of the conflict detector 15B is, as before, that this variant has a low complexity, since the conflict detector 15B only measures the RxD signal.

17 illustrates a configuration of a conflict detector 15C according to a fourth embodiment. The conflict detector 15C and the communication control device 11 according to the present exemplary embodiment are designed like the conflict detector 15 and FIG. 4, except for the differences described below

Communication control device 11 according to the first embodiment.

The conflict detector 15C measures pulse lengths with constant bit-value phases in the TxD signal and RxD signal. The delayed signal TxD_d can optionally be used, as shown by the block 154 shown in dashed lines. Then the comparison of associated pulse lengths takes place. Ideally, the pulse lengths in the TxD signal are identical to the pulse lengths in the RxD signal. For this purpose, the conflict detector 15B has the first counter 151 with which the conflict detector 15C continuously measures the pulse lengths in the TxD signal. In addition, the conflict detector 15C has the second counter 152 with which the conflict detector 15C continuously measures the pulse lengths in the RxD signal. Out the comparison of the pulse lengths with threshold values Ts can be used to derive a conflict with the comparison block 153C.

In addition to the examples for different pulse lengths TI, T2, T3 in the RxDl signal of the subscriber station 10, FIG. 18 shows examples for different pulse lengths T4, T5, T6 in the delayed transmission signal TxDl_d over the time t. The pulse lengths TI, T2, T3, T4, T5, T6 depend on the transmitted bit pattern in the transmission signal TxD1.

The conflict detector 15C thus measures with its counters 151, 152 the 0 phases and 1 phases that occur between two edges of the respective signals TxDl_d, RxDl. As an alternative to the signal TxDl_d of FIG. 18, the counter 151 can measure the 0-phases and 1-phases that occur between two edges of the signal TxDl.

The comparison block 153C compares the measured first 1-phase in the RxD signal, that is to say the pulse length TI in the example of FIG. 18, with the first 1-phase in the TxD signal, that is to say the pulse length T4 in the example of FIG. 18. The comparison is made by forming a difference, eg Asym = T4-Tl. Next, the O phase is compared. The result in the example of Figure 18 is Asym = T5-T2.

The comparison result determined by the comparison block 153C corresponds to the amount of the bit asymmetry asymmetry. If the bit asymmetry Asym exceeds a certain threshold value, there is a bus conflict. The comparison block 153C thus additionally carries out a comparison with a threshold value. The conflict detector 15C, more precisely its comparison block 153C, reports the bus conflict to the communication control device 11 via the conflict indication signal S_K.

The advantage of the previously described function of the conflict detector 15C is that the conflict detector 15C does not require any information about the number of bits in a phase, in particular the data phase 452. The conflict detector 15C only needs to count and then compare. In addition, the conflict detector 15C is implicitly able to also add additional edge changes which are only expected in the event of a bus conflict. Additional edges in the RxD signal generated by the bus conflict would result in the evaluation logic of the comparison block 153C getting mixed up and very large bit asymmetries being determined. If such very large bit asymmetries are determined, the threshold is safely exceeded and the bus conflict is thus detected.

All of the above-described configurations of the conflict detectors 15, 15A, 15B, 15C, 25, 35 and their modifications, of the subscriber stations 10, 20, 30, of the bus system 1 and the method carried out therein can be used individually or in all possible combinations. In particular, all features of the exemplary embodiments described above and / or their modifications can be combined as desired. Additionally or alternatively, the following modifications in particular are conceivable.

Of course, any number of counters 150, 151 can be used for measuring the pulse lengths of the analyzed transmission signal TxD, TxDl, TxD_d in all the exemplary embodiments described above. Of course, any number of counters 150, 152 can be used for measuring the pulse lengths of the analyzed received signal RxD, RxD1 in all the exemplary embodiments described above.

Even if the invention is described above using the example of the CAN bus system, the invention can be used in any communication network and / or communication method in which two different communication phases are used, in which the bus states that are generated for the different communication phases differ. In particular, the invention can be used in the development of other serial communication networks, such as in particular Ethernet, field bus systems, etc.

In particular, the bus system 1 according to the exemplary embodiments can be a communication network in which data can be transmitted serially at two different bit rates. It is advantageous, but not a mandatory requirement, that in the bus system 1 at least for specific time periods an exclusive, collision-free access of a subscriber station 10, 20, 30 to a common channel is guaranteed.

The number and arrangement of the subscriber stations 10, 20, 30 in the bus system 1 of the exemplary embodiments is arbitrary. In particular, the

Subscriber station 20 in bus system 1 is omitted. It is possible for one or more of the subscriber stations 10 or 30 to be present in the bus system 1. It is conceivable that all subscriber stations in the bus system 1 are configured identically, that is to say only subscriber station 10 or only subscriber station 30 are present.

All variants described above for the detection of the bus conflict can be subject to time filtering in order to increase the robustness with regard to electromagnetic compatibility (EMC) and against electrostatic charge (ESD), pulses and other interference.

Claims

Expectations

1) Conflict detector (15; 15A; 15B; 15C; 25; 35) for a subscriber station (10; 20; 30) for a serial bus system (1), with at least one counter (150; 152) for counting the occurrence of a property of Pulsing of a digital received signal (RxD; RxDl) which is generated by the subscriber station (10; 20; 30) from a signal (VDIFF) received serially from a bus (40) of the bus system (1), the signal (VDIFF) received from the bus (40 ) the received signal (VDIFF) was formed from a transmission signal (TxD; TxDl; TxD2) which was sent serially to the bus (40) by a communication control device (11) of the subscriber station (10; 20; 30) for a frame (450) , and wherein the subscriber station (10; 20; 30) in a first communication phase (451; 453, 451) generates bus states (401; 402) for the frame (450) with a first operating mode and in a second communication phase (452) bus states ( 401; 402; U_D0; U_D1) for the frame (450) with a second operating mode that differs from the first n operating mode differentiates, and a comparison block (153; 153A; 153B; 153C), which is designed to compare a measurement result determined from a count value (Zasym; Zrx) of the at least one counter (150; 152) with at least one threshold value (Ts) and to display it with a conflict display signal (S_K) for the communication control device (11) when the comparison block (153; 153A; 153B; 153C) determines in the comparison that the subscriber station (10; 20; 30) does not have exclusive, collision-free access to the bus (40) in the second communication phase (452).

2) conflict detector (15; 15B; 15C; 25; 35) according to claim 1, wherein the property of pulses of the digital received signal (RxD; RxDl) is the level of the pulse, and wherein the at least one counter (150; 152) is designed to count the frequency of occurrence of a first level of the digital received signal (RxD; RxDl) over time or the at least one counter (150) is designed when a first level of the digital signal occurs Received signal (RxD; RxDl) to increment its count value (Zrx) and to decrement its count value (Zrx) when the second level of the digital received signal (RxD; RxDl) occurs.

3) Conflict detector (15; 15B; 15C; 25; 35) according to Claim 1 or 2, the property of pulses in the digital received signal (RxD; RxDl) being the pulse length (TI; T2; T3) of the pulse.

4) Conflict detector (15B; 25; 35) according to one of the preceding claims, wherein the at least one counter (150; 152) and / or the comparison block (153B) are / is designed to determine the property of pulses of the digital received signal (RxD ; RxDl) to use a status signal (S_l) of the communication control device (11), which comprises the clock for sampling bits of the digital received signal (RxD; RxDl) over the time and / or the clock of the communication control device (11).

5) conflict detector (15C; 25; 35) according to claim 3, wherein the comparison block (153C) is designed, the pulse length (TI; T2, T3) of a pulse of the digital received signal (RxD; RxDl) with a pulse length (T4; T5, T6) of a pulse of the transmission signal (TxD; TxDl; TxD2; TxD_d) to determine whether the subscriber station (10; 20; 30) does not have exclusive, collision-free access to the bus (40) in the second communication phase (452) Has.

6) Conflict detector (15A; 25; 35) according to claim 1, wherein the property of pulses of the digital received signal (RxD; RxDl) is the difference between the level of the pulse and the corresponding level of a pulse of the transmitted signal (TxD; TxDl; TxD2; TxD_d) is. 7) Conflict detector (15; 15A; 15B; 15C; 25; 35) according to one of the preceding claims, additionally with at least one additional counter (151) for counting the occurrence of a property of pulses of the digital transmission signal (TxD; TxDl; TxD2; TxD_d ), the comparison block (153; 153A; 153B; 153C) being designed to compare a measurement result determined from the count value (Ztx) of the at least one additional counter (151) with at least one threshold value (Ts) in order to determine whether the Subscriber station (10; 20; 30) in the second communication phase (452) does not have exclusive, collision-free access to the bus (40).

8) Conflict detector (15; 25; 35) according to claim 7, wherein the comparison block (153) is designed to include a count value (Zrx) of the at least one counter (152) which is used to count the occurrence of a property of pulses of the digital received signal (RxD ; RxDl) is provided to be compared with a count (Ztx) of the at least one additional counter (151), which is provided for counting the occurrence of a property of pulses of the digital transmission signal (TxD; TxDl; TxD2; TxD_d) in order to use a the changing difference of the compared count values (Zrx, Ztx) to determine whether the subscriber station (10; 20; 30) does not have exclusive, collision-free access to the bus (40) in the second communication phase (452).

9) conflict detector (15; 15A; 15B; 15C; 25; 35) according to claim 7 or 8, wherein the conflict detector (15A; 25; 35) is designed to use a delayed transmission signal (TxD_d) as the transmission signal, which is delayed by a transit time (TLD) is the delay that the transmit signal (TxD; TxDl; TxD2) needs to be sent from a TxD connection of the

Communication control device (11) to reach an RxD connection of the communication control device (11) via the bus (40).

10) conflict detector (15; 15A; 15B; 15C; 25; 35) according to one of the preceding claims, also with at least one counter for counting rising and / or falling edges of the pulses digital reception signal (RxD; RxDl) or the transmission signal (TxD; TxDl; TxD2; TxD_d).

11) subscriber station (10; 20; 30) for a serial bus system (1), with a communication control device (11; 21; 31) for controlling communication of the subscriber station (10; 20; 30) with at least one other subscriber station (10; 20 ; 30) of the bus system (1), a transmitting / receiving device (12; 22; 32) for transmitting a signal (TxD; TxDl; TxD2) generated by the communication control device (11; 21; 31) for a frame (450) a bus (40) of the bus system (1) and for receiving a signal (VDIFF) from the bus (40), and a conflict detector (15; 15A; 15B; 15C; 25; 35) according to one of the preceding claims, wherein the transmission - / receiving device (12; 22; 32) generated in a first communication phase (451; 453, 451) bus states (401; 402) for the frame (450) with a first operating mode and in a second communication phase (452) bus states (401; 402; U_D0; U_D1) for the frame (450) with a second operating mode that differs from the first operating mode to die.

12) subscriber station (10; 20; 30) according to claim 11, wherein the bus states (401, 402) of the signal (VDIFF) received from the bus (40) in the first communication phase (451; 453, 451) have a longer bit time (T_bl ) have as the bus states (U_D0, U_D1) of the signal received in the second communication phase (452) and / or the bus states (401, 402) of the signal received from the bus (40) in the first communication phase (451; 453, 451) were generated with a different physical layer than the bus states (U_D0, U_D1) of the signal received in the second communication phase (452), and wherein the communication control device (11; 21; 31) is designed to be sent to the conflict detector (15; 15A; 15B; 15C; 25; 35) to output a switch-on signal (S_E) to activate the conflict detector (15; 15A; 15B; 15C; 25; 35) only for the second communication phase (452) to be switched on and switched off for the first communication phase (451; 453, 451) or to switch the conflict detector (15; 15A; 15B; 15C; 25; 35) from one communication phase to another.

13) subscriber station (10; 20; 30) according to claim 11 or 12, wherein in the first communication phase (451; 453, 451) is negotiated which of the subscriber stations (10, 20, 30) of the bus system (1) in the subsequent second Communication phase (452) at least temporarily receives exclusive, collision-free access to the bus (40).

14) Bus system (1), with 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 with one another serially and of which at least one subscriber station (10; 30) is a subscriber station (10; 30) according to one of Claims 11 to 13.

15) A method for detecting a bus conflict in a serial bus system (1), the method using a conflict detector (15;

15A; 15B; 15C; 25; 35) for a subscriber station (10; 20; 30) of the serial bus system (1), and wherein the conflict detector (15; 15A; 15B; 15C; 25; 35) carries out the steps

Counting, with at least one counter (150; 152), of the occurrence of a property of pulses of a digital received signal (RxD; RxDl) which is transmitted by the subscriber station (10; 20; 30) from one of a bus (40) of the bus system (1 ) serially received signal (VDIFF) is generated, the signal (VDIFF) received from the bus (40) being formed from a transmission signal (TxD; TxDl; TxD2) which is generated by a communication control device (11) of the subscriber station (10; 20; 30) was sent serially to the bus (40) in a frame (450), and the subscriber station (10; 20; 30) in a first communication phase (451; 453, 451) bus states (401; 402) for the frame ( 450) with a first operating mode and in a second Communication phase (452) bus states (401; 402; U_D0; U_D1) generated for the frame (450) with a second operating mode that differs from the first operating mode,

Compare, with a comparison block (153; 153A; 153B; 153C), one of a count (Zasym; Zrx) of the at least one

Counter (150; 152) determined measurement result with at least one threshold value (Ts), and

Display with a conflict indication signal (S_K) for the communication control device (11) if the comparison block (153; 153A; 153B; 153C) determines during the comparison that the

Subscriber station (10; 20; 30) has no exclusive, collision-free access to the bus (40) in the second communication phase (452).