DE102019214721A1 - Conflict detector for a subscriber station of a serial bus system and method for communication in a serial bus system - Google Patents

Abstract

A conflict detector (15; 15A; 15B; 25; 35) for a serial bus system (1) and a method for detecting a bus conflict in a serial bus system (1) are provided. The conflict detector (15; 15A; 15B; 25; 35) has a first filter block (151) for filtering a signal (VDIFF) received serially from a bus (40) of the bus system (1), and a second filter block (152) for filtering a digital transmission signal (TxD; TxDl) 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 ) is designed to generate bus states (401; 402) for the frame (450) with a first operating mode in a first communication phase (451; 453, 451) and bus states (401; 402; U_D0; U_D1) in a second communication phase (452) ) for the frame (450) with a second operating mode which differs from the first operating mode, and a detection block (153; 153A) which has a capacitor (1532), at one terminal of which an output of the first filter block (151 ) and an output of the second filter block (152) ang is closed, the detection block (153; 153A) is designed to detect from a voltage (U_C) on the capacitor (1532) whether or not the subscriber station (10; 20; 30) has exclusive, collision-free access to the bus (40) in the second communication phase (452) Not.

Description

Technical area

The present invention relates to 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 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 ISO11898-1: 2015 standard as a CAN protocol specification with CAN FD. The messages are transmitted serially between the bus subscribers of the bus system, such as sensor, control unit, encoder, 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 ( ISO_17987-4 ) 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-T1 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 will be 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 an overlay of driven signals, which results in "analog" levels on the bus. This means that the resulting RxD signal can no longer be precisely predicted and thus 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 detecting 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 resistance 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 a first filter block for filtering a signal received serially from a bus of the bus system, a second filter block for filtering a digital transmission signal that was sent serially to the bus by a communication control device of the subscriber station for a frame, and wherein the subscriber station is designed, in a first communication phase to generate bus states for the frame with a first operating mode and in a second communication phase to generate bus states for the frame with a second operating mode that differs from the first operating mode, and a detection block having a capacitor on one of them Connection is an output of the first filter block and an output of the second filter block is connected, wherein the detection block is designed to detect from a voltage on the capacitor whether or not the subscriber station has exclusive, collision-free access to the bus in the second communication phase.

Due to the configuration of the conflict detector, a transmission conflict in the data phase can be detected from the bus signal in a very uncomplicated, yet very reliable and thus very safe manner, even if both bus states are actively driven in a frame in the data phase. 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 detection or detection of the bus conflict by using the bus signal can be implemented very inexpensively, since only a few additional, but inexpensive components are required for conflict detection by using existing components of the transmitting / receiving device of a subscriber station of the bus system.

In addition, the bus conflict can be detected very precisely by using the bus signal and the transmission signal.

In this way, the transmitting / receiving device (transceiver) for CAN XL can guarantee a very safe operation of the bus system at an affordable price, which favors the use of CAN XL.

Additionally or alternatively, the conflict detector can be provided separately from the transmitting / receiving device (transceiver). It is possible that the bus conflict detection can also be used with currently available CAN transceivers.

Therefore, due to the configuration of the conflict detector, each subscriber station of the bus system is 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 aborting 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 should contain 2-4 KB or more.

As a result, the conflict detector can be used to ensure that the frames are received 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. In this way, communication in the serial bus system can also take place with a high level of error resistance if there is a high data rate and an increase in the amount of useful 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 for the number of bytes per frame are possible, 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. With such a function, the TLD runtime is compensated for by the TxD signal via the transceiver to the RxD signal. The TLD runtime can also be referred to as Transmitter Loop Delay (TLD).

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

It is possible that the detection block is designed to indicate with a conflict display signal for the communication control device when the detection block detects that the subscriber station does not have exclusive, collision-free access to the bus in the second communication phase.

According to one embodiment, the detection block is designed to compare the voltage on the capacitor with a predetermined voltage threshold in order to determine whether the subscriber station does not have exclusive, collision-free access to the bus in the second communication phase.

In a special embodiment, the first filter block has a first low-pass filter and a first voltage-current converter, the first voltage-current converter being connected downstream of the first low-pass filter, the second filter block having an inverter, a second low-pass filter and a second voltage Having current converter, wherein the second voltage-to-current converter is connected downstream of the second low-pass filter, and wherein the capacitor is connected to the output of the first voltage-to-current converter and the output of the second voltage-to-current converter.

In this case, the second low-pass filter can be configured to filter the transmission signal more strongly in the event that the number of 1 states in the transmission signal increases than in the event that the number of 0 states in the transmission signal increases.

The first low-pass filter may have a filter time constant that is less than the number of bit times that an error frame lasts. In addition, the second low-pass filter can have a filter time constant that is smaller than the number of bit times that an error frame lasts.

The capacitor can be connected in parallel to a resistor, the second connection of the resistor being connected to ground.

The conflict detector also optionally has a plausibility check block, the plausibility check block being designed to check at least twice in the duration of an error frame whether the subscriber station does not have exclusive, collision-free access to the bus in the second communication phase.

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 a signal generated by the communication control device for a frame having a bus of the bus system and for receiving a signal from the bus, the transmitting / receiving device generating bus states for the frame with a first operating mode in a first communication phase and generating bus states for the frame with a second operating mode in a second communication phase, which are differ from the first operating mode.

It is possible that the conflict detector is connected in a receiving block of the transmitting / receiving device after a voltage divider in order to tap the signal received serially from the bus as a divided signal.

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.

It is also conceivable that the communication control device is configured to output a switch-on signal to the conflict detector in order to switch on the conflict detector 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 executing the steps of filtering, with a first filter block, a signal received serially from a bus of the bus system, filtering, with a second filter block, a digital transmission signal that was sent serially to the bus by a communication control device of the subscriber station 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, which differs from of the first operating mode, and detecting, with a detection block, a voltage on one Capacitor of the detection block, an output of the first filter block and an output of the second filter block being connected to one connection of the capacitor, and in the step of detecting it is detected whether the subscriber station has exclusive, collision-free access to the bus in the second communication phase or not.

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

• 1 ein vereinfachtes Blockschaltbild eines Bussystems gemäß einem ersten Ausführungsbeispiel;
• 2 ein Schaubild zur Veranschaulichung des Aufbaus von Nachrichten, die von einer Sende-/Empfangseinrichtung für eine Teilnehmerstationen des Bussystems gemäß dem ersten Ausführungsbeispiel gesendet werden können;
• 3 ein vereinfachtes schematisches Blockschaltbild einer Teilnehmerstation des Bussystems gemäß dem ersten Ausführungsbeispiel;
• 4 bis 7 einen zeitlichen Verlauf von Signalen, die im Normalbetrieb in dem Bussystem gemäß dem ersten Ausführungsbeispiel auftreten;
• 8 ein vereinfachtes schematisches Blockschaltbild eines Konfliktdetektors für eine Teilnehmerstation des Bussystems gemäß dem ersten Ausführungsbeispiel;
• 9 einen zeitlichen Verlauf eines Sendesignals TxD1 in einer Datenphase einer Nachricht, die von einer ersten Teilnehmerstation des Bussystems gemäß dem ersten Ausführungsbeispiel gesendet wird;
• 10 einen zeitlichen Verlauf eines Sendesignals TxD2, das von einer anderen Teilnehmerstation zum Abbruch des Sendesignals TxD1 von 8 gesendet wird;
• 11 bis 13 einen zeitlichen Verlauf von Signalen, die sich aufgrund der Sendesignale TxD1, TxD2 von 9 und 10 in dem Bussystem gemäß dem ersten Ausführungsbeispiel einstellen;
• 14 ein vereinfachtes schematisches Blockschaltbild einer Verschaltung des Konfliktdetektors mit dem Empfangsblock einer Sende-Empfangseinrichtung für eine Teilnehmerstation des Bussystems gemäß einem zweiten Ausführungsbeispiel;
• 15 ein vereinfachtes schematisches Blockschaltbild einer Modifikation einer Verschaltung des Konfliktdetektors mit dem Empfangsblock von 14; und
• 16 ein vereinfachtes schematisches Blockschaltbild eines Konfliktdetektors gemäß einem dritten Ausführungsbeispiel.

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

• 1 a simplified block diagram of a bus system according to a first embodiment;
• 2 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 embodiment;
• 3 a simplified schematic block diagram of a subscriber station of the bus system according to the first embodiment;
• 4th to 7th a time profile of signals that occur in normal operation in the bus system according to the first embodiment;
• 8th a simplified schematic block diagram of a conflict detector for a subscriber station of the bus system according to the first embodiment;
• 9 a time profile of a transmission signal TxD1 in a data phase of a message that is sent by a first subscriber station of the bus system according to the first embodiment;
• 10 a time profile of a transmission signal TxD2, which was sent by another subscriber station to the termination of the transmission signal TxD1 from 8th is sent;
• 11 to 13th a time profile of signals that differ due to the transmit signals TxD1, TxD2 from 9 and 10 set in the bus system according to the first embodiment;
• 14th a simplified schematic block diagram of an interconnection of the conflict detector with the receiving block of a transceiver for a subscriber station of the bus system according to a second embodiment;
• 15th a simplified schematic block diagram of a modification of an interconnection of the conflict detector with the receiving block of 14th ; and
• 16 a simplified schematic block diagram of a conflict detector according to a third embodiment.

In the figures, elements that are the same or have the same function are provided with the same reference symbols unless otherwise specified.

Description of the exemplary embodiments

1 shows a bus system as an example 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.

In 1 has the bus system 1 a large number of subscriber stations 10 , 20th , 30th each attached to a bus 40 with a first bus vein 41 and a second bus core 42 are connected. The bus cores 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 the differential level or dominant level or generating recessive levels for a signal in the transmission state.

About the bus 40 are news 45 , 46 in the form of signals between the individual subscriber stations 10 , 20th , 30th serial transferable. The participant stations 10 , 20th , 30th are for example control devices, sensors, display devices, etc. of a motor vehicle.

Occurs when communicating on the bus 40 an error, as indicated by the jagged black block arrow in 1 shown, an error frame 47 (Error Flag) are sent. The error frame 47 consists of six dominant bits, for example.

An error-free message 45 , 46 is confirmed by the receivers by an acknowledge bit, which is a dominant bit that is driven in an acknowledge time slot sent recessively by the sender. Except for the acknowledge time slot, the sender expects a message 45 , 46 that he's on the bus 40 always sees the level that he himself is sending. Otherwise, the sender will recognize the message 45 , 46 a bit error and looks at the message 45 , 46 as invalid. Unsuccessful messages 45 , 46 are repeated.

As in 1 has shown the subscriber station 10 a communication controller 11 , a transceiver 12th and a conflict detector 15th . The participant station 20th on the other hand, has a communication control device 21 , a transceiver 22nd and optionally a conflict detector 25th . The participant station 30th has a communication controller 31 , a transceiver 32 and a conflict detector 35 . The transmitting / receiving devices 12th , 22nd , 32 of the subscriber stations 10 , 20th , 30th are each directly on the bus 40 connected even if this is in 1 is not illustrated.

The communication control devices 11 , 21 , 31 each serve to control a communication of the respective subscriber station 10 , 20th , 30th over the bus 40 with at least one other subscriber station of the subscriber stations 10 , 20th , 30th who got to the bus 40 are connected.

The communication controller 11 creates and reads first messages 45 , for example modified CAN messages 45 are. Here are the modified CAN messages 45 built on the basis of a CAN XL format which is related to 2 is described in more detail.

The communication controller 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 controller 21 creates and reads second messages 46 , for example Classical CAN messages 46 . The Classical CAN messages 46 are structured according to the basic classical format, in which in the message 46 a number of up to 8 data bytes can be included. Alternatively, the CAN message is 46 structured as a CAN FD message, in which a number of up to 64 data bytes can be included, with a significantly faster data rate than with the Classical CAN message 46 be transmitted. In the latter case, it is the communication controller 21 designed like a conventional CAN FD controller.

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

The transmitting / receiving device 12th can be implemented as a CAN XL transceiver apart from the differences described in more detail below. The transmitting / receiving device 22nd can be designed like a conventional CAN transceiver or CAN FD transceiver. The transmitting / receiving device 32 can be run to messages as needed 45 according to the CAN XL format or messages 46 according to the current CAN basic format for the communication control device 31 to provide or receive from it. The transmitting / receiving devices 12th , 32 can also or alternatively be implemented like a conventional CAN FD transceiver.

With the two participant stations 10 , 30th is a formation and then transmission of messages 45 with the CAN XL format as well as the receipt of such messages 45 realizable.

2 shows for the message 45 a CAN XL frame 450 as received from the transceiver 12th or the transceiver 32 is sent. The CAN XL frame 450 is for CAN communication on the bus 40 in different communication phases 451 to 453 divided, namely an arbitration phase 451 , a data phase 452 and a frame end phase 453 .

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

In the data phase 452 the user data of the CAN-XL frame or the message 45 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.

In the frame end phase 453 For example, a checksum for the data of the data phase can be entered in a checksum field 452 including the stuff bits must be contained by the send block of the message 45 after a predetermined number of identical bits, in particular 10 or a different number of identical bits, are inserted as an inverse bit. In addition, a reintegration pattern can be included which enables the receiving subscriber stations to start the frame end phase after an error 453 to find. In addition, in an end field in the frame end phase 453 at least one acknowledge bit must be included. The at least one acknowledge bit can be used to indicate whether a receiver is in the received CAN XL frame 450 or the message 45 discovered a bug or not. In addition, there can be a sequence of 11 identical bits which form the end of the CAN XL frame 450 Show.

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

During the phases 451 , 453 the known CSMA / CR method is used, which allows simultaneous access by the subscriber stations 10 , 20th , 30th on the bus 40 allowed without the higher priority message 45 , 46 gets destroyed. This allows the bus system 1 relatively simple additional bus subscriber stations 10 , 20th , 30th can be added, which is very beneficial.

The CSMA / CR procedure has the consequence that there are so-called recessive states on the bus 40 must give which of other subscriber stations 10 , 20th , 30th with dominant states on the bus 40 can be overwritten. In the recessive state, prevail at the individual subscriber station 10 , 20th , 30th high-resistance conditions, 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 send block 121 according to 3 to send the message 45 starts sending bits of the data phase 452 on the bus 40 only when the subscriber station 10 of the send block 121 the arbitration has won and the subscriber station 10 of the send block 121 This gives exclusive access to the bus for sending 40 of the bus system 1 Has.

1. a) Übernahme und ggf. Anpassung bewährter Eigenschaften, die für die Robustheit und Anwenderfreundlichkeit von Classical CAN und CAN FD verantwortlich sind, insbesondere Rahmenstruktur mit Identifier und Arbitrierung nach dem CSMA/CR-Verfahren,
2. b) Steigerung der Netto-Datenübertragungsrate auf etwa 10 Megabit pro Sekunde,
3. c) Anheben der Größe der Nutzdaten pro Rahmen auf eine beliebige Länge, beispielsweise bis etwa 4 kbyte.

In general, in the bus system 1 With CAN XL compared to Classical CAN or CAN FD, the following different properties can be realized:

1. 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 frame structure with identifier and arbitration according to the CSMA / CR procedure
2. b) Increase in the net data transmission rate to around 10 megabits per second,
3. c) increasing the size of the user 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 12th and the conflict detector 15th . The conflict detector 15th has a first filter block 151 , a second filter block 152 and a detection block 153 .

The participant station 30th is structured in a similar way as in 3 shown except that the conflict detector 35 not in the transceiver 32 is integrated, but separately from the communication control device 31 and the transceiver 32 is provided. Is the detector 25th is present, the transceiver is 22nd in relation to the detector 15th identical to the transmitter / receiver device 12th built up. Therefore, the subscriber stations 20th , 30th and the conflict detectors 25th , 35 not described separately. The functions of the conflict detector described below 15th are with the conflict detectors 25th , 35 identical available.

According to 3 has the subscriber station 10 in addition to the communication control device 11 , the transmitting / receiving device 12th and the conflict detector 15th also a microcontroller 13th , which the communication control device 11 and a system ASIC 16 (ASIC = application-specific integrated circuit), which can alternatively be a system base chip (SBC) on which several for an electronic assembly of the subscriber station 10 necessary functions are summarized. In the system ASIC 16 is in addition to the transceiver 12th an energy supply device 17th built in, which is the transmitter / receiver 12th supplied with electrical energy. The energy supply device 17th usually supplies from one port 43 a CAN_Supply voltage of 5 V. Depending on requirements, the energy supply device 17th however deliver a different voltage with a different value. Additionally or alternatively, the energy supply device 17th be designed as a power source.

The transmitting / receiving device 12th also has a send block 121 and one Receiving block 122 . Even if subsequently always from the transmitting / receiving device 12th is spoken, it is alternatively possible to use the receive block 122 in a separate device external to the transmission block 121 to be provided. The send block 121 and the reception block 122 can as with a conventional transceiver 22nd be constructed. The send block 121 can in particular have at least one operational amplifier and / or one transistor. The reception block 122 can in particular have at least one operational amplifier and / or one transistor.

The transmitting / receiving device 12th is to the bus 40 connected, more precisely its first bus core 41 for CAN_H or CAN-XL_H and its second bus wire 42 for CAN_L or CAN-XL_L. About at least the connection 43 the voltage supply for the energy supply device takes place 17th to supply the first and second bus cores 41 , 42 with electrical energy, especially with the CAN supply voltage. The connection to ground or CAN_GND is via a connector 44 realized. The first and second bus cores 41 , 42 are with a terminating resistor 49 terminated.

The first and second bus cores 41 , 42 are in the transceiver 12th not only with the send block 121 , also known as the transmitter, and with the receiving block 122 also known as the receiver, even if the connection is in 3 is not shown for the sake of simplicity. The signals CAN_H, CAN_L of the first and second bus wire 41 , 42 in the transceiver 12th also for the conflict detector 15th available. The first and second bus cores 41 , 42 in the transceiver 12th also with the conflict detector 15th be connected. This is in relation to 8th described in more detail below.

During the operation of the bus system 1 can send the block 121 , in the transmitting mode of the transmitting / receiving device 12th , a transmission signal TXD or TxD of the communication control device 11 with digital states 0 (State L) and 1 (State H) in corresponding signals Data_0 and Data_1 for the bus wires 41 , 42 implement. The transmission signal TXD or TxD is shown schematically in 3 and more precisely in 4th illustrated. The send block 121 can then these signals Data_0 and Data_1 according to 4th at the connections for CAN_H and CAN_L or CAN-XL_H and CAN-XL_L on the bus 40 send as in 5 shown.

The reception block 122 of 3 trains from the bus 40 at the connections CAN_H, CAN_L received bus signals on CAN-XL_H and CAN-XL_L according to 5 a differential voltage VDIFF according to 6th and converts this into a received signal RXD or RxD with digital states 0 (State L) and 1 (State H), as shown schematically in 3 illustrated and as in 7th shown in more detail. The reception block 122 of 3 outputs the received signal RXD or RxD to the communication control device 11 continue as in 3 shown. With the exception of an idle or standby state (idle or standby), the transceiver listens 12th with the reception block 122 in normal operation always on a transmission of data or messages 45 , 46 on the bus 40 regardless of whether the transmission block 121 Sender of the message 45 is or not.

4th to 7th illustrate signals in normal operation of the bus system 1 . The transceiver thus sets 12th in the course of time t a transmission signal TXD or TxD of the communication control device 11 according to 4th 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 in 5 shown. From the signals CAN-XL_H and CAN-XL_L from 5 forms on the bus 40 A differential voltage VDIFF = CAN-XL_H - CAN-XL_L over the time t, the course of which in 6th is shown.

The sequence of the data states H, L from 4th and thus the resulting bus states U_D0, U_D1 for the signals CAN-XL_H, CAN-XL_L in 5 and the resulting course of the voltage VDIFF from 6th and the received signal RxD from 7th serves only to illustrate the function of the transmitting / receiving device 12th . The sequence of the data states H, L from 4th and thus the resulting bus states U_D0, U_D1 in 5 and the signals from 6th and 7th can be selected as required.

The transmitting / receiving device 12th trains from the bus 40 received signals CAN-XL_H and CAN-XL_L with reception thresholds T_u, T_d according to 6th the received signal RXD or RxD, as in 7th shown over time t.

For the phases 451 , 453 In normal operation, at least one reception threshold T_u is used, which is shown in the hatched area in the left-hand part of 6th lies. As in 6th uses the transceiver 12th in the communication phases 451 , 453 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, for the bus states 401 , 402 to be able to reliably recognize in the first operating mode. On the other hand, for the data phase 452 switched to at least one reception threshold T_d in the hatched area in the right part of 6th lies. The transmitting / receiving device 12th give that Received signal RXD or RxD to the communication control device 11 continue as in 3 shown.

According to the example of 5 and 6th have the signals CAN-XL_H and CAN-XL_L in the aforementioned communication phases 451 , 453 corresponding to the states H (High), L (Low) of the transmission signal TxD from 4th the dominant bus levels 401 and recessive bus levels 402 as known from CAN. In contrast, the signals CAN-XL_H and CAN-XL_L differ according to 5 in the data phase 452 from the conventional signals CAN_H and CAN_L. In the data phase 452 instead of the bus level 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. On the bus 40 the difference signal VDIFF = CAN-XL_H - CAN-XL_L is formed, as in 6th shown.

In addition, a first bit time T_bt1 in the phases 451 , 453 to a second bit time T_bt2 in the phase 452 switched. The first bit time T_bt1 can be greater than the second bit time T_bt2, even if this is in 4th to 7th is not shown for the sake of simplicity. In this case, the bits of the signals are in phases 451 , 453 transmitted more slowly than in the data phase 452 . At a bit rate of, for example, 10 Mbit / s in the data phase 452 the second bit time T_bt2 has the value 100ns.

Thus the bit duration T_bt2 is in the data phase 452 in the example of 4th to 7th significantly shorter than the bit duration T_bt1, which is in the arbitration phase 451 and the frame end phase 453 is used.

The transmitting / receiving device 12th is thus of the state corresponding to the left part of 5 for the data phase 452 switched to the state corresponding to the right part of 5 corresponds to. The transmitting / receiving device 12th is thus switched from a first operating mode to a second operating mode.

8th shows a structure of the conflict detector 15th for an operational case in the data phase 452 can be used, which is based on 9 to 13th illustrated and described below.

The conflict detector 15von 8th has in the first filter block 151 a low pass filter 1511 and a voltage-to-current converter 1512 . In addition, the second filter block has 151 a low pass filter 1521 and a voltage-to-current converter 1522 . The acquisition block 153 has a resistance 1531 and a capacitor 1532 that are connected in parallel. In addition, the acquisition block has 153 a detector 1533 , its input to the output of the first filter block 151 and to the output of the second filter block 152 connected. In addition, there is the entrance to the detector 1533 to the end of the parallel circuit made of resistor 1531 and capacitor 1532 connected to the output of the first filter block 151 and to the output of the second filter block 152 connected. The other end of the parallel circuit made of resistor 1531 and capacitor 1532 is on a connector 43 connected for the system ground CAN_GND. On the capacitor 1532 and thus the detector 1533 a voltage U_C is present.

Detects or detects the detector 1533 by evaluating the voltage U_C that is on the bus 40 a collision with an error frame 47 occurs, the detector generates 1533 a corresponding state in a conflict indication signal S_K. The collision detector 15th can thus cause the collision and thus the conflict on the bus 40 with the conflict indication signal S_K, as described below. The conflict display signal S_K can in particular via the connection RxD or via an additional connection to the communication control device 11 be sent.

During the operation of the bus system 1 receives the conflict detector 15th with the first filter block 151 the differential voltage VDIFF and forms it with the low pass 1511 a filtered differential voltage VDIFF_F, which is shown in 12th is shown. The voltage-current converter 1512 converts the filtered differential voltage VDIFF_F into an electrical current 11 holding the capacitor 1532 loads. The conflict detector also receives 15th with the second filter block 152 the transmission signal TxD and forms it with an inverter 1520 an inverted transmission signal and with the low pass 1521 a filtered inverted transmission signal TxD_F, more precisely a filtered inverted transmission signal voltage TxD_F, which in 9 is shown. The voltage-current converter 1522 converts the filtered inverted transmission signal TxD_F into an electrical current 12th holding the capacitor 1532 discharges.

In other words, the differential voltage VDIFF charges the capacitor 1532 on, the inverted signal TxD discharges the capacitor 1532 . If both signals have the same signal course, the voltage U_C on the capacitor remains at 0V.

If the differential voltage VDIFF has more logic 0 levels (VDIFF> 0) than are sent via the transmit signal TxD, the capacitor becomes 1532 charged and U_C rises until the conflict on the bus 40 is recognized.

The total current l3 on the capacitor 1532 is calculated according to equation (1) as $$\text{I.}3=\text{I.}1-\text{I.}2$$

If the two currents l1 and l2 are of the same magnitude, then the current l3 = 0 A. This means that the voltage U_C = 0 V. Thus, the capacitor becomes 1532 not loaded.

Small deviations between the currents I1 and I2 settle with the resistance 1531 dissipate. This results in a mismatch between the two voltage / current converters 1512 , 1522 of 8th compensable.

However, if the differential voltage VDIFF and thereby also the filtered differential voltage VDIFF_F rise, whereas the transmission signal TxD and thereby the filtered inverted transmission signal TxD_F remain constant, then the capacitor becomes 1532 loaded. This increases the voltage U_C across the capacitor 1532 on and is used by the detector 1533 checked with a predetermined voltage threshold T_K, which in 12th is shown.

The predetermined voltage threshold T_K can be configured by a user. The predetermined voltage threshold T_K is preferably taking into account the signal curves from 9 to 13th certainly.

The in 9 to 13th The case shown, for example, sends the transmitting / receiving device 12th the transmission signal TxD1 as the transmission signal TxD for one frame 450 , where for example the subscriber station 30th that are in the data phase 452 actually only recipient of the frame 450 is an abortion of the frame 450 wants to reach and therefore sends the transmit signal TxD2. Thus occurs on the bus 40 a transmission conflict in which the subscriber station 10 in the data phase 452 no more exclusive, collision-free access to the bus 40 Has.

• - die Teilnehmerstation 30 als RX-Teilnehmerstation hat einen Fehler in der Kopfprüfsumme (Header Prüfsumme oder CRC = Cyclic Redundancy Check) der CAN XL-Nachricht 45 festgestellt, und möchte dies signalisieren, und/oder
• - die Teilnehmerstation 20, die eine CAN FD Teilnehmerstation ist, hat eventuell das Umschalten zu dem Format des Rahmens 450 aufgrund eines Bit Fehlers nicht erkannt und sendet einen Fehlerrahmen 47 während der Datenphase 452 des Rahmens 450, und/oder
• - die Teilnehmerstation 30 als RX-Teilnehmerstation hat eine Nachricht 45, 46 mit höherer Priorität zu senden, und/oder
• - zwei CAN-XL-Teilnehmerstationen, beispielsweise die Teilnehmerstationen 10, 30 verwenden versehentlich den gleichen Identifizierer und senden somit beide in der Datenphase 452.

There are several reasons why the frame could be broken off 450 should take place:

• - the subscriber station 30th as an RX subscriber station has an error in the header checksum (header checksum or CRC = Cyclic Redundancy Check) of the CAN XL message 45 detected and would like to signal this, and / or
• - the subscriber station 20th , which is a CAN FD subscriber station, may have to switch to the format of the frame 450 not recognized due to a bit error and sends an error frame 47 during the data phase 452 of the frame 450 , and or
• - the subscriber station 30th as RX subscriber station has a message 45 , 46 to send with higher priority, and / or
• - two CAN-XL subscriber stations, for example the subscriber stations 10 , 30th accidentally use the same identifier and thus both send in the data phase 452 .

For example, the subscriber station would like 30th an abortion of the frame 450 reach which the transmitting / receiving device 12th with the signal TxD1 of 9 sends, the subscriber station sends 30th the transmission signal TxD2 according to 10 to the bus 40 . In the phase 455 of sending the error frame 47 , which begins with the falling edge of the transmission signal TxD2 at a point in time t2, are therefore obtained according to 11 and 12th Voltage states for CAN_XL_H, CAN_XL_L on the bus 40 that depends on the voltage states on the bus 40 in normal operation of the data phase 452 according to 5 differ.

In general, the sending subscriber station that sends the send signal TxD1 is in the data phase 452 for driving the bus cores 41 , 42 switches to a transmit operating mode. In contrast, for all receiving subscriber stations, such as the subscriber stations 10 , 30th , in the 11 shown at least one reception threshold Td switched on. In this case, however, the bus driver of the only receiving subscriber station remains 30th in the passive receiving state (CAN recessive state) until the receiving subscriber station 30th possibly the error frame 47 sends, as in 10 for the transmission signal TxD2 shown and mentioned above. The error frame 47 according to the right part of 10 will then be actively sent as "dominant". In order to enable the interoperability of CAN XL and CAN FD, an error frame 47 As with CAN / CAN FD, it is represented by the stringing together of 6 or more (depending on the bit stuffing method) bits with positive VDIFF.

In the case described above, it is used by the subscriber station 30th an error frame 47 sent, then changes accordingly 11 the transient course of the differential voltage VDIFF is very strong. From the point of view of all participant stations 10 , 20th , 30th a bit with a positive differential voltage VDIFF, i.e. the bus state U_D1, is further amplified or the positive differential voltage VDIFF is increased. In contrast, a bit that appears as the bus state U_D0 is on the bus 40 trains, increased from the differential voltage VDIFF = -2 V to a differential voltage VDIFF of about 0V. The resulting voltage value for the bus state U_D0 depends heavily on the parameters of the driving transmitting / receiving devices 12, 22, 32 or the transmitter 121 , as well as the arrangement of the terminating resistors 49 from.

About the representation of 12th In addition, the differential voltage VDIFF is still superimposed by high-frequency oscillations in the real case, which are determined by the bus topology, phase position and impedance of the subscriber station, the error frame 47 sends. 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).

The conflict detector 15th of 8th therefore compare with the detector block 1533 the voltage U_C with the voltage threshold T_K of 12th .

If the voltage threshold T_K is exceeded, this is seen as a collision with an error frame 47 recognized, according to 10 is sent from time t2 with the transmit signal TxD2. If the voltage threshold T_K is exceeded, the collision detector shows 15th this with the conflict indication signal S_Kan.

If the filtered differential voltage VDIFF_F increases and the filtered transmission signal TxD_F is reduced, then the capacitor is 1532 no further loading. As a result, the voltage U_C remains at around 0V. The voltage U_C is also from the detector block 1533 with the voltage threshold T_K of 12th checked and / or compared. If the voltage threshold T_K of 12th is not exceeded by the voltage U_C, this is interpreted in such a way that there is no collision with an error frame 47 takes place.

1. 1.) Es wurde durch eine andere Teilnehmerstation 10, 20, 30 ein Fehlerrahmen 47 auf den Bus 40 gesendet.
2. 2.) Die von der Teilnehmerstation 10 gesendeten Daten enthalten mehr 0-Zustände (L-Zustände) als bei der letzten Messung oder Erfassung, was ebenfalls zu einem Anstieg der gefilterten Differenzspannung VDIFF_F führen würde.

In other words, to a conflict between several, but at least two, transmitting / receiving devices 12th , 22nd , 32 to recognize the signal VDIFF im from the conflict detector 15th , 25th , 35 captured and low-pass filtered. The output signal of the low pass filter 1511 is observed. If the output signal of the low-pass filter increases 1511 this can have the following causes:

1. 1.) It was through another subscriber station 10 , 20th , 30th an error frame 47 on the bus 40 sent.
2. 2.) The one from the subscriber station 10 The data sent contain more 0 states (L states) than in the last measurement or acquisition, which would also lead to an increase in the filtered differential voltage VDIFF_F.

May be the cause 2 .) are excluded, it is an error frame 47 or is the cause 1 .) in front. To the cause 2 .), the inverted TxD signal is also low-pass filtered. The output signal of the low pass filter 1521 is observed. If the voltage VDIFF_F increases while the signal TxD_F remains the same, this must be the cause 1 .), that is, a margin of error 47 are present.

With the conflict detector 15th is the filter time constant tau_TP for each of the low pass filters 1512 , 1522 designed according to the following regulation: $$\text{TLD}<\text{dew}\_\text{TP}<\mathrm{6th}\text{x T}\_\text{bt}1$$

Thus, the filter time constant should be tau_TP for each of the low pass filters 1512 , 1522 greater than the runtime TLD but less than 6 bit times T_bt1 for bits in the phases 451 , 453 be. In general, the filter time constant should be tau_TP for each of the low-pass filters 1512 , 1522 have a value smaller than the number of bit times T_bt1 that make up one error frame 47 lasts. Has an error frame 47 a number of 6 bits of the arbitration phase 451 , for example, 255ns <tau_TP <6 × 2µs, if T_bt1 = 2µs applies.

Also is the conflict detector 15th configured in such a way that the low-pass filtering of the transmission signal TxD is configured asymmetrically. For this purpose, the transmission signal TxD, if the 1 or H states in the transmission signal TxD increase, with the low-pass filter 1521 filtered to a greater extent than the transmission signal TxD is filtered when the 0 or L states in the transmission signal TxD increase. The filter time constant tau_TP of the second low-pass filter 1522 is therefore in the operation of the bus system 1 variable. This will balance the following two cases.

In the event that the 0 or L states increase in the signal TxD, the current l2 formed from the filtered inverted transmission signal TxD_F would increase earlier than the current formed from the filtered signal VDIFF_F I1 . Due to the asymmetrical filtering of the low-pass filter 1521 avoids incorrectly setting an error frame 47 is detected when the filtered voltage VDIFF_F increases.

In the event that the 1 or H states in the signal TxD increase, the current l2 formed from the filtered transmission signal TxD_F would decrease earlier than the current l1 formed from the filtered signal VDIFF_F. As a result, the voltage U_C would rise and incorrectly an error frame 47 be recognized. Due to the asymmetrical filtering of the low-pass filter 1521 can such erroneous detection of the detection block 153 be avoided.

These measures ensure that the TLD (Propagation Delay) does not incorrectly interfere with the conflict detector during the runtime 15th a detection of a send conflict or bus conflict is indicated.

The communication controller 11 reacts in the data phase 452 to the send conflict or bus conflict signaled with the signal S_K the termination of the data phase 452 and, if necessary, additionally with the transmission of a bit pattern, for example an error frame 47 that the other subscriber stations 20th , 30th the end of the data phase 452 signals. The communication controller 11 switches to the arbitration phase 451 back.

At the participant stations 20th , 30th can signaling the conflict in the data phase 452 by the conflict indication signal S_K from the respective transceiver 22nd , 32 to the associated communication control device 21 , 32 respectively. The signal can be the received signal RXD, which the corresponding transmitting / receiving device 22nd or the conflict detector 35 modified with a predetermined bit pattern to signal the conflict. Alternatively or additionally, the corresponding transmitting / receiving device 22nd , 32 or the conflict detector 25th , 35 generate a separate signal, which is sent via a separate signal line to the associated communication control device 21 , 31 is sent and in particular has at least one switching pulse or a predetermined bit pattern for signaling the conflict.

Because in the data phase 452 the send conflict or bus conflict to the associated communication control device 11 , 21 , 31 is signaled, the bit error check conventional in classic CAN can be replaced by comparing the transmit signal TXD with the receive signal RXD by checking the conflict indication signal S_K. The conflict display signal S_K has, in particular, a predetermined bit pattern which signals or displays the transmission conflict or bus conflict. In particular, the conflict display signal S_K can send a '1' as an “OK signal” and a “0” as a “conflict message”.

What is particularly advantageous about the variants of the evaluation described above is that the design of the transmitting / receiving device 12th both for homogeneous CAN-XL bus systems in which only CAN XL messages 45 and no CAN FD messages 46 can be sent, and can also be used for mixed bus systems in which either CAN XL messages 45 or CAN FD messages 46 be shipped. Hence the transceiver 12th universally applicable.

An additional advantage of the previously described function of the conflict detector 15th is that the conflict detector 15th no information about the number of bits in a phase, especially the data phase 452 , required. On top of that is the conflict detector 15th implicitly able to detect additional edge changes that are only expected in the event of a bus conflict. This is because additional edges in the RxD signal generated by the bus conflict would lead to the evaluation logic of the communication control device 11 being mixed up.

14th shows a configuration of a reception block 122 having a conflict detector 15A is connected according to a second embodiment. The reception block 122 has one on the input side on the bus wires 41 , 42 provided voltage divider 1221 , a preload module 1222 , a receiving comparator 1223 and a comparator 1224 for a wake-up call 126 . The wake-up circuit 126 can implement an energy-saving mode in which the receive block 122 Only receives electrical power when on the bus 40 communication takes place.

In contrast to conventional receive blocks and the preceding implementation of 8th is in the present embodiment in the receive block 122 instead of VDIFF = CAN_H - CAN_L or VDIFF = CAN_XL_H - CAN_XL_L that through the voltage divider 1221 divided down signal VDIFF_D for the conflict detector 15th used. A node in the receive comparator can tap the signal VDIFF_D 1223 of the receive block 122 to get voted.

In this way the circuit for the conflict detector 15A of 8th in the low voltage range (5V range). This reduces the semiconductor area requirement of the transmitting / receiving device 12th . This reduces the space requirement and the costs for the transmitting / receiving device 12th decreased, which is very beneficial.

The communication control device optionally sends 11 and / or the transmitting / receiving device 12th to the conflict detector 15A an enable signal or switch-on signal S_E if the conflict detector 15A should only work during a valid send process. In particular, the communication control device 11 be designed to the conflict detector 15A to output a switch-on signal S_E to the conflict detector 15A only for the data phase 452 switch on and for the other phases 451 , 453 turn off. In particular, it is alternatively possible that the conflict detector 15A the signal S_E is used to switch from one communication phase to another communication phase. In this way the conflict detector can be switched to energy-saving mode 15th will be realized.

15th shows a configuration of a reception block 1220 that with the conflict detector 15A is connected according to the second embodiment. Here this is through the voltage divider 1221 divided down signal VDIFF_D for the conflict detector 15th not in the receiving comparator 1223 tapped, but directly after the voltage divider 1221 .

In this way, too, the circuit for the conflict detector 15A of 8th in the low-voltage range (5V range), so that the same advantages with regard to the semiconductor area requirement of the transmitter / receiver 12th can be achieved.

16 Fig. 10 shows a configuration of a conflict detector 15B according to a third embodiment.

At the conflict detector 15B becomes, in contrast to the conflict detector 15th of 8th , the query of the detector result several times, but at least twice, within the time of a possible error frame 47 repeated. The time of a possible margin of error 47 lasts, for example, 6 time periods T_bt1 of a bit of the arbitration phase 451 .

The conflict detector has 15B of the present embodiment also in its acquisition block 153B a plausibility block 1534 at the exit of the conflict detector 15B . The plausibility block 1534 has at least one flip-flop 341 , 342 which is connected as a shift register. Only when a predetermined number of U_C levels has been recognized that indicates a conflict on the bus 40 will indicate a conflict with an error frame 47 recognized. As a result, the conflict detector 15B signals the conflict with the conflict indication signal S_K, as described in the previous exemplary embodiments.

This allows the conflict detector 15B compared to the conflict detector 15th of 8th in addition, security against incorrect triggering of the conflict detector 15A increase. So that's from the conflict detector 15A generated conflict display signal S_K even more precisely and detects the conflict on the bus 40 even safer than in the previous embodiments.

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

Even if the invention is described above using the example of the CAN bus system, the invention can be used in any communication network and / or communication method in which two different communication phases are used in which the bus states 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, it can be a communication network in which data can be transmitted serially at two different bit rates. It is advantageous, but not an absolute prerequisite, that in the bus system 1 an exclusive, collision-free access by a subscriber station at least for certain periods of time 10 , 20th , 30th on a common channel is guaranteed.

The number and arrangement of the subscriber stations 10 , 20th , 30th in the bus system 1 of the exemplary embodiments is arbitrary. In particular, the subscriber station 20th in the bus system 1 omitted. It is possible that one or more of the subscriber stations 10 or 30th in the bus system 1 available. It is conceivable that all subscriber stations in the bus system 1 are designed the same, so only subscriber station 10 or only subscriber station 30th available.

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 disturbances.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Non-patent literature cited

• ISO 11898-2 [0004]
• ISO_17987-4 [0004]
• ISO 17458-4 [0004]

Claims (15)

Conflict detector (15; 15A; 15B; 25; 35) for a subscriber station (10; 20; 30) for a serial bus system (1), with a first filter block (151) for filtering a signal (VDIFF; VDIFF_D) received serially from a bus (40) of the bus system (1), a second filter block (152) for filtering a digital transmission signal (TxD; TxD1) which was sent serially to the bus (40) for a frame (450) by a communication control device (11) of the subscriber station (10; 20; 30), and wherein the subscriber station (10; 20; 30) is designed to generate bus states (401; 402) for the frame (450) with a first operating mode in a first communication phase (451; 453, 451) and in a second communication phase (452) To generate bus states (401; 402; U_D0; U_D1) for the frame (450) with a second operating mode that differs from the first operating mode, and a detection block (153; 153A) which has a capacitor (1532) to one terminal of which an output of the first filter block (151) and an output of the second filter block (152) are connected, wherein the detection block (153; 153A) is designed to detect from a voltage (U_C) on the capacitor (1532) whether the subscriber station (10; 20; 30) in the second communication phase (452) has exclusive, collision-free access to the Bus (40) has or not. Conflict detector (15; 15A; 15B; 25; 35) after Claim 1 , wherein the detection block (153; 153A) is designed to indicate with a conflict indication signal (S_K) for the communication control device (11) when the detection block (153; 153A) detects that the subscriber station (10; 20; 30) is in the second communication phase (452) does not have exclusive, collision-free access to the bus (40). Conflict detector (15; 15A; 15B; 25; 35) after Claim 1 or 2 , wherein the detection block (153; 153A) is designed to compare the voltage (U_C) on the capacitor (1532) with a predetermined voltage threshold (T_K) 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). Conflict detector (15; 15A; 15B; 25; 35) according to one of the preceding claims, wherein the first filter block (151) has a first low-pass filter (1511) and a first voltage-to-current converter (1512), wherein the first voltage-to-current converter (1512) is connected downstream of the first low-pass filter (1511), wherein the second filter block (152) has an inverter (1520), a second low-pass filter (1521) and a second voltage-current converter (1522), wherein the second voltage-to-current converter (1522) is connected downstream of the second low-pass filter (1521), and wherein the capacitor (1532) is connected to the output of the first voltage-to-current converter (1512) and the output of the second voltage-to-current converter (1522). Conflict detector (15; 15A; 15B; 25; 35) after Claim 4 , the second low-pass filter (1521) being designed to filter the transmission signal (TxD; TxDl) more intensely than in the case that in the transmission signal (TxD; TxDl) the number of 1-states increases Transmission signal (TxD; TxDl) the number of 0 states increases. Conflict detector (15; 15A; 15B; 25; 35) after Claim 4 or 5 , wherein the first low-pass filter (1511) has a filter time constant that is smaller than the number of bit times (T_bt1) that an error frame (47) lasts, and wherein the second low-pass filter (1521) has a filter time constant that is smaller than the number of Is bit times (T_bt1) that an error frame (47) lasts. Conflict detector (15; 15A; 15B; 25; 35) according to one of the preceding claims, wherein the capacitor (1532) is connected in parallel to a resistor (1531), and wherein the second terminal of the resistor (1531) is connected to ground (44). Conflict detector (15B; 25; 35) according to one of the preceding claims, wherein the acquisition block (153B) also has a plausibility check block (1534), the plausibility check block (1534) being designed to check at least twice in the duration of an error frame (47) 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. 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) on 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; 25; 35) according to one of the preceding claims, wherein the transmitting / receiving device (12; 22; 32) generates bus states (401; 402) for the frame (450) with a first operating mode in a first communication phase (451; 453, 451) and bus states in a second communication phase (452) (401; 402; U_D0; U_D1) are generated for the frame (450) with a second operating mode, which differ from the first operating mode. Subscriber station (10; 20) after Claim 9 , wherein the conflict detector (15A; 15B; 25; 35) is connected in a receiving block (122) of the transmitting / receiving device (12; 22) after a voltage divider (1221) in order to convert the signal ( VDIFF_D) as a divided signal. Subscriber station (10; 20; 30) after Claim 9 or 10 , 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_b1) than 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). Subscriber station (10; 20; 30) after one of the Claims 9 to 11 , wherein the communication control device (11; 21; 31) is designed to output a switch-on signal (S_E) to the conflict detector (15; 15A; 15B; 25; 35) in order to activate the conflict detector (15; 15A; 15B; 25; 35) only to be switched on for the second communication phase (452) and to be switched off for the first communication phase (451; 453, 451) or to switch the conflict detector (15; 15A; 15B; 25; 35) from one communication phase to another. Subscriber station (10; 20; 30) after one of the Claims 9 to 12th , wherein in the first communication phase (451; 453, 451) it 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 an exclusive, collision-free access to the bus ( 40) gets. 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 ; 20; 30) a subscriber station (10; 20; 30) after one of the Claims 9 to 13th is. Method for detecting a bus conflict in a serial bus system (1), the method being carried out with a conflict detector (15; 15A; 15B; 25; 35) for a subscriber station (10; 20; 30) of the serial bus system (1), and wherein the conflict detector (15; 15A; 15B, 25; 35) carries out the steps Filtering, with a first filter block (151), a signal (VDIFF; VDIFF_D) received serially from a bus (40) of the bus system (1), Filtering, with a second filter block (152), of a digital transmission signal (TxD; TxDl) which was sent serially to the bus (40) for a frame (450) by a communication control device (11) of the subscriber station (10; 20; 30) , 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) is generated for the frame (450) with a second operating mode that differs from the first operating mode, and Detecting, with a detection block (153; 153A), a voltage (U_C) on a capacitor (1532) of the detection block (153; 153A), wherein an output of the first filter block (151) and an output of the second filter block (152) are connected to a connection of the capacitor (1532), and wherein in the step of detecting it is detected whether or not the subscriber station (10; 20; 30) has exclusive, collision-free access to the bus (40) in the second communication phase (452).

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