CN115640252A - Method for identifying a manipulation in a serial bus system and transmitting/receiving device - Google Patents

Abstract

A transmitting/receiving apparatus and method of identifying an operation in a serial bus system. The transmission/reception apparatus has: a first comparator for evaluating a signal received from a bus of the bus system with a first reception threshold; a second comparator for evaluating signals received from the bus with a second receive threshold or a steering identification receive threshold, the comparators using different receive thresholds, the second receive threshold being set to determine: whether the communication on the bus is in a first or second communication phase for sending frames to the bus; a driver for driving the digital reception signal to the communication control means of the subscriber station; a logic circuit to: forwarding output signals of the first comparator and the second comparator to the driver if a second receiving threshold is set in the second comparator and the communication on the bus is in the first communication stage; and if a manipulation recognition reception threshold is set in the second comparator, forwarding only the output signal of the first comparator to the driver; and a connection terminal for outputting an output signal of the second comparator to the communication control device.

Description

Method for identifying a manipulation in a serial bus system and transmitting/receiving device

Technical Field

The invention relates to a method and a transmitting/receiving device for detecting manipulations in a serial bus system, in which communication is carried out, in particular, with differential signals.

Background

Serial bus systems are used for message or data transmission in technical installations. For example, a serial bus system may enable communication between sensors and control devices in a vehicle or a technical production facility or the like. Different standards or data transmission protocols exist for data transmission. Known are, in particular: CAN bus system, LVDS bus system (LVDS = Low Voltage Differential Signaling), MSC bus system (MSC = Micro-Second-Channel), 10 BASE-T1S-ethernet.

In the case of a CAN bus system, messages are transmitted by means of the CAN and/or CAN FD protocols, as described in standard ISO-11898-l:2015, which is a CAN protocol specification with CAN FD. In the case of CAN FD, the transmission is switched back and forth between a slow mode in the first communication phase (arbitration phase) and a fast mode in the second communication phase (data phase). In the case of a CAN FD bus system, a data transmission rate of more than 1Mbit per second (1 Mbps) is achieved in the second communication phase. Most manufacturers use CAN FD in vehicles first with an arbitration bit rate of 500kbit/s and a data bit rate of 2 Mbit/s.

In order to achieve still greater data rates in the second communication phase, there are successor bus systems for CAN FD, such as CAN-SIC and CAN XL. In the case of a CAN-SIC according to the standard CiA601-4, a data rate of approximately 5 to 8Mbit/s CAN be achieved in the second communication phase. In the case of CAN XL, a data rate of > 10Mbit/s is required in the second communication phase, for which the standard (CiA 610-3) is currently set in the CAN In Automation (CiA) organization. In addition to pure data transmission via the CAN bus, CAN XL should support other functions, such as functional Security (Security), data Security (Security), and Quality of Service (QoS = Quality of Service). This is a basic characteristic required in an automatic traveling vehicle.

When communicating in a bus system, there is a risk of network manipulation. Such a manipulation exists if at least one subscriber station (node) is removed and/or added by an unauthorized person in the bus system and/or the line length of the stations in the network is changed. Such manipulation is at least undesirable and primarily involves (though not exclusively): a great safety risk in the case of automatically driven vehicles. Currently, however, the functionality for identifying network manipulations (Intrusion Detection) is not included in these standardized specifications for CAN bus systems (standarddisierging service), such as ISO 11898-2.

Disclosure of Invention

The task of the invention is therefore: a method and a transmitting/receiving device for identifying manipulations in a serial bus system are provided, which solve the above-mentioned problems. In particular, a method and a transmitting/receiving device for detecting manipulations in a serial bus system should be provided, with which the security for the bus system and thus also the security of the communication in the bus system can be increased.

This object is achieved by a method and a transmitting/receiving device for identifying manipulations in a serial bus system having the features of claim 1. The transmission/reception device includes: a first comparator for evaluating signals received from a bus of the bus system with a first reception threshold, a second comparator for evaluating signals received from the bus with a second reception threshold or a maneuver identification reception threshold, wherein the reception thresholds used by these comparators are different, and wherein the second reception threshold is set or configured for determining: whether the communication on the bus is in a first communication phase or a second communication phase for sending frames onto the bus; a driver (Treiber) for driving the communication control means of the digital reception signal to the user station; a logic circuit for forwarding an output signal of the first comparator and an output signal of the second comparator to the driver if the second reception threshold is set in the second comparator and the communication on the bus is in the first communication phase, and for forwarding only the output signal of the first comparator to the driver if the manipulation recognition reception threshold is set in the second comparator; and a connection terminal for outputting an output signal of the second comparator to the communication control device.

The described transmitting/receiving device is configured in such a way that a reliable and effortless detection of an actuation is possible by checking the bus signals during operation of the bus system. This also applies in particular to communications in which the physical layer switches between two communication phases for communication on the bus.

It is furthermore advantageous: the transmitting/receiving device can use already existing components for recognizing signals for normal communication in the bus system. The transmitting/receiving device can thus be set up as a function with little effort and therefore at relatively low cost.

Here, the described transmission/reception apparatus realizes: in particular, the CAN XL meets the requirements for differential signaling (vorgabin) for communication. These specifications for this are established for CAN XL, in particular with the standard CiA610-3 (festschreiben).

Thereby, the transmission/reception apparatus ensures: the access (hinzuschalten) or disconnection (wegschealten) of a subscriber station or a change in the line network of the bus system can be reliably detected. Then, it may be decided to: whether the subscriber station is allowed to be switched in or out. The subscriber station can be switched in or out in an allowed manner, for example on the basis of maintenance of components of the bus system.

Furthermore, the transmitting/receiving device is configured in such a way that the signal level of the bus signal can be converted into a digital received signal by synchronously evaluating the two reception thresholds. The two reception thresholds used in the individual communication phases can be different depending on the communication phase. At least one reception threshold can be used to identify manipulations of the bus system.

Thereby, the transmitting/receiving apparatus realizes the following functionality: different receive thresholds are used for arbitration and data phases and identification manipulations. Thereby, not only is communication in the bus system at a higher bit rate achieved, but also the transmittable bit rate is not cut down due to errors in the communication and/or manipulation of the bus system.

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

The input of the second comparator can be low-pass filtered (tiefpassfilter) with less intensity than the input of the first comparator, wherein the output of the second comparator can be low-pass filtered with less intensity than the output of the first comparator.

According to one variant, the connection is a connection which is provided or designed for outputting only the output signal of the second comparator to the communication control device.

According to another variant, the connection is a connection that can be operated in a multiplexing method for at least two functions of the transmitting/receiving device.

The transmitting/receiving device may have a control circuit for switching the reception threshold of the second comparator from the second reception threshold to the manipulation detection reception threshold for a predetermined time duration in a frame transmitted onto the bus of the bus system.

The transmitting/receiving device may furthermore have a protocol controller which is configured to detect, in the frame, a predetermined point in time at which the control circuit is to execute a control for switching the reception threshold of the second comparator.

The transmitting/receiving device may furthermore have a function type detection block which is designed to detect a predetermined point in time in the frame at which the control circuit is to execute a control for switching the reception threshold of the second comparator.

It is conceivable that: the manipulation circuit performs manipulation for switching the reception threshold of the second comparator if the transmission/reception apparatus is a recipient of the frame.

According to one exemplary embodiment, the transmitting/receiving device further has a voltage divider, which is connected to the bus, for providing the signals received from the bus for the first comparator and for the second comparator, wherein the first comparator and the second comparator are connected to the voltage divider in such a way that the signals are evaluated synchronously.

According to another embodiment, the transmitting/receiving device further comprises: a first voltage divider for setting the first or third receive threshold, wherein the first comparator is connected to the first voltage divider for evaluating signals received from the bus of the bus system with the first or third receive threshold set by the first voltage divider; a second voltage divider for setting the second reception threshold or a manipulation recognition reception threshold as a fourth reception threshold, wherein the second comparator is connected to the second voltage divider for evaluating a signal received from the bus with the second or fourth reception threshold set by the second voltage divider, and wherein the first and second voltage dividers are connected to the bus, respectively. In this case, the first and second voltage dividers have a circuit consisting of resistors, to which first and second comparators are connected, wherein the first and second comparators evaluate the signals synchronously. Additionally or alternatively, at least one of the first and second voltage dividers may have at least one switching unit for switching between the second and fourth reception thresholds for the second comparator depending on the type of operation of the transmitting/receiving device which is to be switched to for the first or second communication phase of the communication on the bus. It is possible to arrange at least one switching unit for connecting the voltage divider to the ground line or for disconnecting the voltage divider from the ground line.

Optionally, there is at least one second comparator.

The aforementioned transmitting/receiving means can be part of a subscriber station for a serial bus system, wherein the subscriber station furthermore has communication control means for controlling the communication in the bus system and for generating a digital transmit signal for the transmit module.

It is possible that the communication control device has a protocol controller which is configured to evaluate the output signal from the second comparator of the connection.

The communication control device may have a timer for controlling the protocol controller in time, wherein the timer is also configured to evaluate the output signal from the second comparator of the connection.

Optionally, the subscriber station is configured for communication in a bus system, wherein at least temporarily: the subscriber stations access the bus of the bus system in an exclusive, conflict-free manner.

The object is also achieved by a method for detecting manipulations in a serial bus system having the features of claim 19. The method is carried out using a transmitting/receiving device of a subscriber station of a serial bus system, wherein the transmitting/receiving device has: first comparator, second comparator, driver and link. The method comprises the following steps: evaluating, by a first comparator, a signal received from a bus of the bus system with a first reception threshold; evaluating the signals received from the bus by means of a second comparator with a second reception threshold or a steering recognition reception threshold, wherein the reception thresholds used by the comparators are different, and wherein the second reception threshold is set or configured to determine: whether the communication on the bus is in a first communication phase or a second communication phase for sending frames onto the bus; forwarding, by the logic circuit, the output signal of the first comparator and the output signal of the second comparator to the driver if the second reception threshold is set in the second comparator and the communication on the bus is in the first communication phase, and forwarding, by the logic circuit, only the output signal of the first comparator to the driver if the manipulation recognition reception threshold is set in the second comparator; and driving the digital reception signal to the communication control means of the subscriber station through the driver; and the output signal of the second comparator is output on the connection to the communication control device.

This method provides the same advantages as mentioned previously in relation to the transmitting/receiving device.

Other possible implementations of the invention also include: combinations of features or embodiments not explicitly mentioned before or below in relation to the embodiments. The person skilled in the art will also add individual aspects here, as a supplement or improvement to the corresponding basic form of the invention.

Drawings

The invention is further described below with reference to the drawings and in accordance with embodiments.

Wherein:

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

fig. 2 shows a diagram for illustrating a message structure, in which the message can be transmitted by a subscriber station of the bus system according to the first exemplary embodiment;

fig. 3 shows an example of an ideal temporal profile for the bus signals CAN _ H, CAN _ L in the bus system;

fig. 4 shows the temporal course of the differential voltage VDIFF which is formed on the bus of the bus system as a result of the bus signals of fig. 4;

fig. 5 shows a simplified block diagram of a subscriber station of a bus system with a communication control device and a transmitting/receiving device according to a first embodiment;

fig. 6 shows a circuit diagram of a receiving circuit for a receiving module of a transmitting/receiving apparatus according to the first embodiment;

fig. 7 shows a circuit diagram of a comparator of a receiving module according to the first embodiment;

fig. 8 shows a simplified block diagram of a subscriber station of a bus system with a communication control device and a transmitting/receiving device according to a second embodiment;

fig. 9 shows an example of a temporal profile for a digital transmit signal which, according to the second exemplary embodiment, in an arbitration phase (SIC operating type) is to be converted into bus signals CAN _ H, CAN _ L for the buses of the bus system of fig. 1;

fig. 10 shows a time-variant sequence of the bus signals CAN _ H, CAN _ L when switching the recessive bus state into the dominant bus state and back into the recessive bus state, these bus signals being transmitted to the bus in an arbitration phase (SIC operating type) on the basis of the transmission signals of fig. 9;

fig. 11 shows an example of a temporal profile for a digital transmit signal which, according to the second exemplary embodiment, is to be converted in the data phase into bus signals CAN _ H, CAN _ L for the bus of the bus system of fig. 1;

fig. 12 shows a temporal profile of the bus signals CAN _ H, CAN _ L, which are transmitted to the bus in the data phase on the basis of the transmission signals of fig. 11;

fig. 13 shows a simplified block diagram of a subscriber station of a bus system with a communication control device and a transmitting/receiving device according to a third embodiment;

fig. 14 shows a simplified block diagram of a subscriber station of a bus system with a communication control device and a transmit/receive device according to a fourth embodiment;

fig. 15 shows a simplified block diagram of a subscriber station of a bus system with a communication control device and a transmitting/receiving device according to a fifth embodiment; and

fig. 16 shows a circuit diagram of a receiving circuit of a receiving module of a transmitting/receiving apparatus according to a sixth embodiment.

In these figures, identical and functionally identical elements are provided with the same reference symbols unless otherwise indicated.

Detailed Description

Fig. 1 shows a bus system 1, which bus system 1 may be, for example, a CAN bus system, a CAN FD bus system, etc., at least in sections. The bus system 1 may be used in a vehicle (in particular a motor vehicle), an aircraft or the like, or in a hospital or the like.

In fig. 1, a bus system 1 has a plurality of subscriber stations 10, 20, 30, each of which is connected to a bus 40 or bus line having a first bus line 41 and a second bus line 42. The bus cores 41, 42 may also be referred to as CAN _ H and CAN _ L for signals on the bus 40. Messages 45, 46, 47 in the form of signals can be transmitted between the individual user stations 10, 20, 30 via the bus 40. The user stations 10, 20, 30 can be, for example, control devices or display devices of a motor vehicle.

As shown in fig. 1, the subscriber stations 10, 30 each have a communication control device 11 and a transmitting/receiving device 12. The transmission/reception device 12 has a transmission module 121 and a reception module 122.

The subscriber station 20 has a communication control means 21 and a transmitting/receiving means 22. The transmission/reception device 22 has a transmission module 221 and a reception module 222.

The transmit/receive means 12 of the subscriber stations 10, 30 and the transmit/receive means 22 of the subscriber station 20, respectively, are directly connected to the bus 40, even if this is not shown in fig. 1.

The communication control means 11, 21 are each used to control the communication of the respective subscriber station 10, 20, 30 with at least one other subscriber station of the subscriber stations 10, 20, 30 connected to the bus 40 via the bus 40.

The communication control device 11 creates and reads first messages 45, 47, which are for example modified CAN messages 45, 47. In this case, the modified CAN message 45, 47 is constructed, for example, based on the CAN XL format. The transmitting/receiving means 12 are arranged to transmit and receive messages 45, 47 from the bus 40. The transmit module 121 receives the digital transmit signal TxD created by the communication control device 11 for one of the messages 45, 47 and converts it into a signal on the bus 40. The receiving module 121 receives the signals transmitted on the bus 40 corresponding to the messages 45 to 47 and generates therefrom a digital received signal RxD. The receiving module 122 sends a receiving signal RxD to the communication control apparatus 11.

The communication control device 21 CAN be implemented as a conventional CAN controller according to ISO 11898-1. The communication control means 21 creates and reads a second message 46, for example a CAN FD message 46. The transmit/receive device 22 is used to transmit and receive messages 46 from the bus 40. The transmit module 221 receives the digital transmit signal TxD created by the communication control device 21 and converts it into a signal for the message 46 on the bus 40. The receiving module 221 receives the signals transmitted on the bus 40 corresponding to the messages 45 to 47 and generates therefrom a digital receive signal RxD. Otherwise, the transmitting/receiving means 22 may be implemented as a conventional CAN transceiver.

For the transmission of messages 45, 47 in CAN SIC or CAN XL, validated (bw 228hrt) features are used, in particular a frame structure with identifiers and arbitration according to the known CSMA/CR method, wherein these validated features are responsible for the robustness and user-friendliness of CAN and CAN FD. The result of this CSMA/CR method is that there must be a so-called recessive state on the bus 40, which can be overwritten by other user stations 10, 20, 30 with a dominant level or a dominant state on the bus 40.

This can be achieved by means of the two subscriber stations 10, 30: messages 45 having different CAN formats, in particular CAN FD format or CAN SIC format or CAN XL format, are formed and then transmitted, and such messages 45 are received, as described in more detail below.

If an error occurs during communication in the bus system 1, at least one of the subscriber stations 10, 20, 30 can send at least one error frame 48 to the bus 40 in order to inform the other subscriber stations 10, 20, 30 about the error.

Fig. 2 shows a frame 450, in particular a CAN XL frame, for the message 45, as provided by the communication control device 11 for the transmitting/receiving device 12 for transmission onto the bus 40. In this case, the communication control apparatus 11 creates the frame 450 as a frame compatible with CAN FD in the present embodiment. Alternatively, the frame 450 is compliant with a CAN SIC.

According to fig. 2, the frame 450 is divided into different communication phases 451, 452 for CAN communication on the bus 40, namely an arbitration phase 451 (first communication phase) and a data phase 452 (second communication phase). After the start bit SOF, the frame 450 has an arbitration field 453, a control field 454, a data field 455, a checksum field 456, and an end of frame field 457. After the transmitting/receiving device 12 has transitioned from the operation type of the data phase 452 to the operation type of the arbitration phase 451, the bit AL1 is transmitted in the end-of-frame field 457.

In the arbitration phase 451, the negotiation between the subscriber stations 10, 20, 30 takes place bit by bit, for example with the aid of an Identifier (ID) with the bit IDs 28 to 18 in the arbitration field 453: which subscriber station 10, 20, 30 wants to send the message 45, 46 with the highest priority and thus gets exclusive (exclusive) access to the bus 40 of the bus system 1 for the next time for transmission in the following data phase 452. In the arbitration phase 451, a Physical Layer (Physical Layer) is used as in CAN and CAN-FD. The physical layer corresponds to a bit transport layer or layer 1 of a known OSI model (Open Systems Interconnection model).

An important point during phase 451 is that known CSMA/CR methods are used which allow the user station 10, 20, 30 to access the bus 40 simultaneously, without corrupting the higher priority messages 45, 46. It is thereby possible to add other bus user stations 10, 20, 30 to the bus system 1 relatively simply, which is very advantageous.

A consequence of the CSMA/CR method is that a so-called recessive state must be present on the bus 40, which recessive state can be overwritten on the bus 40 by a further subscriber station 10, 20, 30 with a dominant level or a dominant state. In the recessive state, a high resistance situation prevails at the respective subscriber station 10, 20, 30, which in combination with the parasite of the bus wiring has the consequence of a longer time constant. This results in limiting the maximum bit rate of today's CAN FD physical layer to now about 2 megabits per second in real vehicle use.

In the data phase 452, in addition to the part of the control field 454, useful data of the CAN-XL frame 450 or of the message 45 from the data field 455 are transmitted, as well as a checksum field 456. The checksum field 456 may contain a checksum of the data in the data phase 452, including stuffing bits (stuffbits) which are inserted by the sender of the message 45 as opposite bits after a predetermined number of identical bits, in particular 10 identical bits, in each case. At the end of the data phase 452, the arbitration phase 451 is switched back again.

At least one acknowledgement bit may be included in the end field in the end of frame phase 457. There is also a sequence of 11 identical bits that indicate the end of the CAN XL frame 450. The at least one acknowledgement bit CAN be used to inform the receiver whether an error has been found in the received CAN XL frame 450 or message 45.

The sender of the message 45 only begins to transmit the bits of the data phase 452 onto the bus 40 when the subscriber station 10 as sender has won an arbitration and the subscriber station 10 as sender thus has gained exclusive access to the bus 40 of the bus system 1 for transmission.

Therefore, the subscriber stations 10, 30 use the format known from CAN/CAN-FD according to ISO11898-1 2015 partially, in particular up to (including) the FDF bit, in the arbitration phase 451 as first communication phase. In contrast to CAN or CAN FD, however, in the data phase 452 as second communication phase a rise in the net data transmission rate is achieved, in particular to more than 10 megabits per second. Furthermore, it is also possible to increase the size of the useful data per frame, in particular to approximately two kilobytes or any other value.

Fig. 3 shows on the left side: the subscriber station 10, 20, 30 transmits signals CAN _ H, CAN _ L onto the bus 40 in an arbitration phase 451, which signals alternately have at least one dominant state 401 or at least one recessive state 402. After arbitration in the arbitration phase 451, one of the subscriber stations 10, 20, 30 is determined to be the winner. Suppose that: subscriber station 10 wins arbitration. The transmitting/receiving means 12 of the subscriber station 10 then switches its physical layer from the first operating type (SLOW) to the second operating type (FAST TX) at the end of the arbitration phase 451, since the subscriber station 10 is the sender of the message 45 in the data phase 452. The transmit module 121 then generates the states L0 and L1 of the signals CAN _ H, CAN _ L on the bus 40 in succession and thus in series as a function of the transmit signal TxD in the data phase 452 or in the second operating mode (FAST _ TX). The frequency of the signals CAN _ H, CAN _ L CAN be increased in the data phase 452, as shown on the right in fig. 3. Thus, the net data transfer rate is increased in the data phase 452 compared to the arbitration phase 451. In contrast, at the end of the arbitration phase 451, the transmitting/receiving means 12 of the subscriber station 30 switches its physical layer from the first operating type (SLOW) to the third operating type (FAST _ RX), since the subscriber station 30 is only the receiver, i.e. not the sender, of the frame 450 in the data phase 452. After the end of the arbitration phase 451, all transmitting/receiving means 12 of the subscriber stations 10, 30 switch their own operating type to the first operating type (SLOW). Therefore, all the transmission/reception devices 12 also switch their physical layers.

According to fig. 4, in the arbitration phase 451, ideally a differential voltage VDIFF = CAN _ H-CAN _ L is formed on the bus, which has a value VDIFF =2V for the dominant state 401 and a value VDIFF = 0V for the recessive state 402. This is shown on the left side in fig. 4. In contrast, as shown on the right in fig. 4, in the data phase 452, the differential voltage VDIFF = CAN _ H-CAN _ L with states L0, L1 is formed on the bus 40. This state L0 has a value VDIFF = 1V. This state L1 has a value VDIFF = -1V.

The receive module 122 may distinguish between the states 401, 402 or L0, L1 using two of the receive thresholds T1, T2, T3, respectively, where the receive thresholds are within the ranges TH _ T1, TH _ T2, TH _ T3. Further, the reception threshold T4 can be used. To distinguish between states or voltage levels on the bus 40 it is possible to: the receiving module 122 operates continuously in time or samples the signals of fig. 3 or fig. 4 at a time point t _ a. Alternatively or additionally, in the communication control device 11, at the time of the sampling Point (Sample-Point) t _ a: the received signal RxD, more precisely the RxD level/bit, generated by the receiving module 122 is sampled. The receiving module 122 uses a receiving threshold T1 of, for example, 0.7V and a receiving threshold T2 of, for example, -0.35V or a receiving threshold T4 of, for example, +0.35V in the arbitration phase 451 for the purpose of evaluating the signals VDIFF and/or CAN _ H, CAN _ L. The reception threshold T2 is used at least during a predetermined time TA at which the arbitration takes place. Instead, the receiving module 122 uses the receiving threshold T3 in the data phase 452 for evaluating the signal VDIFF and/or CAN _ H, CAN _ L. In switching between the first to third operation types (SLOW, FAST _ TX, FAST _ RX) described earlier with reference to fig. 3, the receiving module 122 switches the receiving thresholds T1, T2, T3, T4, respectively, as described below. It is also possible to switch between the reception thresholds T2, T4 during the arbitration phase 451. For example, the threshold of the receiving module 122 may be switched by a device, in particular the control circuit 158 of fig. 5. The apparatus recognizes that: there is a conversion (Wechsel) of the coding of the data of the transmission signal TxD. In particular, the NRZ coding in the transmitted signal TxD may indicate: it should switch to the arbitration phase 451 (SLOW). In particular, the PWM coding in the transmission signal TxD may indicate: for the data phase 452, a switch should be made to which type of operation, namely: switching to operating type FAST TX if the subscriber station is the sender of frame 450 or operating type FAST RX if the subscriber station is the only recipient of frame 450.

When subscriber station 12 should newly engage in a communication on bus 40 and attempt to join (integrieren) a communication on bus 40, then receive threshold T2 is used to identify: whether the bus 40 is idle. This reception threshold T2 is abbreviated as OOB (= Out-of-Boundary = outside limit value) in the standard for CAN. The conditions for the no communication (verkehrsfrei) CAN-XL bus are: the dominant state 401, which typically has a differential voltage VDIFF =2V, does not occur. Therefore, the reception threshold T1 of, for example, 0.7V is not allowed to be exceeded. Furthermore, the level according to the state L1 is not allowed to occur, wherein the state L1 typically has a differential voltage VDIFF = -1V. Therefore, a reception threshold T2 lower than, for example, -0.35V is not allowed.

In the event that a subscriber station 12 is to be newly connected to a communication on bus 40, each subscriber station 10, 30 switches the type of operation of transmitting/receiving means 12 to the type of operation of arbitration phase 451.

On the one hand, access by the subscriber station 10 may be required in the event that the subscriber station 10 is initially initiated and should join a communication over the bus 40. On the other hand, in the case where the subscriber station 10 attempts to join the communication on the bus 40 again after an error in the bus communication, access by the subscriber station 10 may be required. Only if a bus free is detected, the subscriber station 10 is allowed to send data, in particular messages 45, 47, to the bus 40 itself in this case.

As described in more detail below, the reception threshold T4 serves to identify a maneuver in the bus system 1. If arbitration ends before the start of arbitration for a new frame 450 or at the end of frame 450, the receive threshold T4 is enabled in arbitration phase 451 (einschalten).

Table 1 below shows the values that CAN be set according to the standard CiA610-3 for CAN XL for the respective reception threshold on the bus 40. Here, VIDFF _ min illustrates a lower limit for each range TH _ T1, TH _ T2, TH _ T3, which is allowed to be set at the minimum for the corresponding reception threshold T1, T2, T3 in units of V. VDIFF _ typ illustrates the value that is typically or commonly set for the corresponding reception threshold T1, T2, T3 in units of V. VIDFF _ max illustrates the upper limit for each range TH _ T1, TH _ T2, TH _ T3 that is allowed to be set at maximum for the corresponding reception threshold T1, T2, T3 in units of V.

Table 1: tolerance ranges for the thresholds T1, T2, T3 are received.

Further, instead of the reception threshold T2, the transmission/reception apparatus 12 of fig. 1 may enable the reception threshold T4 of fig. 4. The reception threshold T4 may have a value of about VDIFF = + 0.35V. In particular, the reception threshold T4 has a value in a range from VIDFF _ min = +0.25V up to VIDFF _ max = + 0.45V.

The receiving module 122 detects the slack and/or oscillations on the bus cores 41, 42 using the receiving threshold T4. The reception threshold T4 is selected such that a slack on the bus 40 can be detected. If the bus system 1 is subjected to an actuation intervention, the signal change processes at the connection ends CANH, CANL change. Thereby, the differential voltage VDIFF = CAN _ H-CAN _ L is also caused to vary. The evaluation of the change is the basis for the detection and identification of the above-mentioned network manipulations. For the evaluation, the oscillations and/or the slack on the bus cores 41, 42 before the manipulation are compared with the oscillations and/or the slack on the bus cores 41, 42 after the manipulation. The difference in the signal of the differential voltage VDIFF before and after manipulation may be shown in the simulation and/or measurement. For this purpose, the subscriber station is configured as follows.

Fig. 5 shows in more detail the basic structure of a subscriber station 10 with communication control means 11 and transmission/reception means 12.

The communication control apparatus 11 has a protocol controller 111 and a timer 112, which can receive signals from the transmission/reception apparatus 12. The protocol controller 111 and the timer 112 are each configured to sample signals for communication in the bus system 1 and to measure and evaluate the pulse duration of signals for communication in the bus system 1. The timer 112 presets a clock pulse (Zeittakt) for the communication in the bus system 1.

The protocol controller 111 creates and interprets the messages 45, 46, 47 in the bus 40 having the communication standard. As mentioned above, this communication standard may be in particular CAN SIC or CAN XL. For this purpose, the communication control device 11, in particular the protocol controller 111 thereof, generates and transmits the TxD signal to the transmission/reception device 12 as described above. Furthermore, the communication control device 11 evaluates the RxD signal as described above. The protocol controller 111 furthermore has an evaluation block 1111 for the signal CA2 of the transmitting/receiving device 12, a memory block 1112 and a manipulation reaction block 1113. After the first commissioning of the bus system 1, for example in the case of a first reception of the signal CA2 on the bus 40, the signal CA2 is stored in the memory block 1112 as a reference value CA2_0. The reference value CA2_0 corresponds to the emission spectrum of the bus 40 which is not manipulated.

The timer 112 may also have an evaluation block 1121 for the signal CA2 of the transmission/reception device 12, a storage block 1122 and a manipulation reaction block 1123. The evaluation block 1121 has the same function as the evaluation block 1111. The memory block 1122 has the same function as the memory block 1112. The manipulation reaction block 1123 has the same function as the manipulation reaction block 1113. Thus, the signal CA2 of the transmitting/receiving device 12 may be forwarded to the protocol controller 111 and/or the timer 112 for evaluation.

The transmitting module 121 of the transmitting/receiving device 12 is shown only in a very simplified manner. The transmit module 121 is connected directly to the bus 40 in order to be able to transmit a transmit signal TxD of the communication control device 11 to the bus 40 in order to generate a signal according to fig. 3 on the bus 40.

The receive module 122 of the transmit/receive device 12 has a driver 1221 for a digital receive signal RxD, a logic circuit 1222, a driver 1225 for a signal CA2 and a receive circuit 15. The reception circuit 15 includes: a first reception comparator 151 that outputs a signal CA1; a second reception comparator 152 that outputs a signal CA2; a receiver electrode 153; a Bus bias voltage source (Bus-Biasing) 154, connections 155, 156 and an operating circuit 158. These reception comparators 151, 152 are low-voltage comparators, respectively.

The receiving circuit 15 is connected between the bus 40 and the logic circuit 1222. The driver 1221 is connected to the output terminal of the logic circuit 1222. The driver 1221 drives or transmits the digital reception signal RxD to the communication control apparatus 11. The driver 1225 drives or sends the digital signal CA2 to the communication control device 11. This signal CA2 can be forwarded from the device 12 to the device 11 at the additional connection C2 of the transmitting/receiving device 12 and at the additional connection of the communication control device 11.

The output signal CA2 can be forwarded directly to the communication control device 11 or to the communication control device 11 in a filtered manner at the additional connection C2 of the transmitting/receiving device 12. This connection C2 can be an additional connection C2 on the transmitting/receiving device 12. Alternatively, the connection C2 is an existing (bestehend) connection, for example a prepared connection (STB), which is used in a multiplexed manner.

In the case of the receiving circuit 15, the receiver electrode 153 is connected to the bus line 40. In operation of the bus system 1, the receiver electrode 153 further generates signals S _1, S _2 from the signals CAN _ H, CAN _ L to the first receiver comparator 151. The first receiving comparator 151 generates a comparator output signal CA1 from the signals S _1 and S _2. This signal CA1 is output to the logic circuit 1222 at the connection 155.

In addition, during operation of the bus system, the receiver electrode 153 additionally generates and transmits (weitergeben) signals S _3, S _4 from the signals CAN _ H, CAN _ L to the second reception comparator 152. The second receiving comparator 151 generates a comparator output signal CA2 from the signals S _3 and S _4. This signal CA2 is output at connection 156 to a logic circuit 1222. Furthermore, as mentioned above, the signal CA2 is output to the communication control device 11 on the connection C2.

The comparator output signal CA1 depends on: which receive threshold is enabled in the first comparator 151. For this purpose, the receiving circuit 15 has a control circuit 158 which controls the setting of the receiving threshold T1 (fig. 4) or the receiving threshold T3 (fig. 4) in the receiving comparator 151. This is described in more detail with reference to the second comparator 152 in accordance with fig. 6 and 7.

The comparator output signal CA2 depends on: to which type of operation the transmitting/receiving device 12, more precisely the second comparator 152, is switched. The control circuit 158 or the second control circuit 158 controls setting of the reception threshold T2 (fig. 4) or the reception threshold T4 (fig. 4) in the reception comparator 152. This is described in more detail in accordance with fig. 6 and 7.

The logic circuit 1222 is configured to output the signals CA1 and CA2 to the driver 1221 or output only the signal CA1 to the driver 1221 depending on the operation type of the transmission/reception device 12. To this end, the logic circuit 1222 may have at least one and gate. Alternatively, the logic circuit 1222 has other logic blocks in order to satisfy the functions described below of the receiving module 122.

As shown in fig. 6, the receiver electrode 153 furthermore has a first input filter 1531 for the first comparator 151, a second input filter 1532 for the second comparator 152 and a voltage divider 1533. The voltage divider 1533 is a resistive or resistive voltage divider.

The voltage divider 1533 is supplied with a voltage from a Bus-Biasing source (Bus-Biasing) 154. The bus bias source 154 typically provides a voltage CAN _ SUPPLY/2 to the receiver electrode 153, more specifically, a voltage divider 1533. Typically, CAN _ SUPPLY =5V is applicable. In this case, the bus bias source 154 supplies 2.5V to the receiver 153. The voltage from the bus bias source 154 may be set to 2.5V, among other things, for the recessive state 402 (fig. 3).

The voltage divider 1533 has a first resistor and a second resistor R _ CH1, R _ CH2 for the bus signal CAN _ H. In addition, the voltage divider 1533 has a third and a fourth resistor R _ CL1, R _ CL2 for the bus signal CAN _ L. The voltage divider 1533 divides the bus voltage generated by the signals CAN _ H, CAN _ L into values that CAN be processed by the comparators 151, 152. The circuit of the resistors in the resistor network of the voltage divider 1533 is constructed symmetrically.

The first resistor R _ CH1 is connected to the bus core 41 (CANH) at one of its ends. The first resistor R _ CH1 is connected in series with the second resistor R _ CH2 at the other end thereof. The third resistor R _ CL1 is connected to the bus line 42 (CANL) at one of its ends. The third resistor R _ CL1 is connected in series with the fourth resistor R _ CL2 at the other end thereof. A bus bias source 154 is connected at the junction between the resistors R _ CH2, R _ CL2.

The resistance R _ filt _ CH _ B of the input filter 1532 and the resistance R _ filt _ CH _ a of the input filter 1531 for the CAN _ H signal path are connected at the connection between the resistances R _ CH1, R _ CH2. The resistance R _ filt _ CL _ B of the input filter 1532 and the resistance R _ filt _ CL _ a of the input filter 1531 for the CAN _ L signal path are connected at the connection between the resistances R _ CL1, R _ CL2.

The first input filter 1531 for the first comparator 151 has a first RC element for the CAN _ H signal path and a second RC element for the CAN _ L signal path. The first RC element additionally has a capacitance C _ filt _ CH _ a relative to the resistance R _ filt _ CH _ a. The second RC element additionally has a capacitance C _ filt _ CL _ a relative to the resistance R _ filt _ CL _ a. These capacitors C _ filt _ CH _ a, C _ filt _ CL _ a are each connected at one end to the ground line or to the connection 44 for CAN _ GND.

The second input filter 1532 for the second comparator 152 has a first RC element for the CAN _ H signal path and a second RC element for the CAN _ L signal path. The first RC element additionally has a capacitance C _ filt _ CH _ B with respect to the resistance R _ filt _ CH _ B. The second RC element additionally has a capacitance C _ filt _ CL _ B relative to the resistance R _ filt _ CL _ B. These capacitors C _ filt _ CH _ B, C _ filt _ CL _ B are each connected at one end to the ground line or to the connection 44 for CAN _ GND.

The two comparators 151, 152 therefore use the same voltage divider 1533. This is achieved by using the voltage divider 1533 in common: both reception thresholds are evaluated simultaneously or synchronously. This evaluation circuit 158 enables the switching of the reception thresholds T1, T3 in the first comparator 151 by means of the signal sw _ th 1. Furthermore, the control circuit 158 makes it possible to switch the reception thresholds T2, T4 in the second comparator 152 by means of the signal sw _ th 2. This is shown in table 2 as the assignment of the output signals CA1, CA2 of the comparators 151, 152 to the reception thresholds T1, T2, T3, T4.

Table 2 assignment examples for the output signals CA1, CA2 and the reception thresholds T1, T2, T3, T4 of the comparators 151, 152.

Thus, the reception thresholds T1, T2 or the reception thresholds T1, T4 are evaluated simultaneously or synchronously in an arbitration phase 451 by means of the reception circuit 15, wherein the transmitting/receiving means 12 are switched to the run type SLOW for the arbitration phase. After switching the reception thresholds in the first and second comparators 151, 152, these reception thresholds T3, T2 are evaluated simultaneously or synchronously in a data phase 452, in which the transmitting/receiving device 12 is switched to the operating type FAST TX, FAST RX for the data phase.

The first comparator 151 may be a reception comparator known from CAN. The signal CA1 at the output of the comparator 151 is output via the logic circuit 1222 only via the connection for the signal RxD. Additionally, the first comparator 151 is switchable as described in more detail below with respect to the second comparator 152.

The second input filter 1532 for the second comparator 152 performs low pass filtering of a smaller strength than the first input filter 1531 for the first comparator 151. In other words, the second input filter 1532 has a larger bandwidth for the CAN _ H signal path than the first comparator 151. Therefore, the second input filter 1532 has a higher limit frequency for the CAN _ H signal path than the first comparator 151. In addition, the second input filter 1532 has a larger bandwidth for the CAN _ L signal path than the first comparator 151. Therefore, the second input filter 1532 has a higher limit frequency for the CAN _ L signal path than the first comparator 151. Furthermore, the output of the second comparator 152 is not low-pass filtered or is low-pass filtered to a lesser extent than the output of the first comparator 151. This is possible because the second comparator is present primarily for the purpose of processing the CAN XL signals of other subscriber stations transmitting according to the bus states L0, L1 of fig. 3 in the data phase 452. These bus states L0, L1 are transmitted from the transmitting/receiving device 12 at a higher bit rate and with a lower impedance. The properties of the comparator 152 are furthermore used in the arbitration phase 451 to identify manipulations in the bus system 1. The transmitting subscriber stations 10, 30 proceed in the following manner for this purpose.

These subscriber stations 10, 30 check in arbitration during time TA: whether the subscriber station is allowed to transmit its frame 450 in the next data phase 452. For this purpose, it is checked by using comparators 151, 152: whether another subscriber station wants to send a message 45, 46, 47 with a higher priority. If not, the bus 40 is idle. If the bus 40 is guaranteed to be idle, the transmitting/receiving device 12 starts transmitting the frame 450 onto the bus 40. The second comparator 152 now no longer needs to check whether the bus 40 is free. Thus, before the data of frame 450 is sent on bus 40 in data phase 452, the second comparator 152 is now used to compare the course of the change of the differential voltage VDIFF with a high bandwidth with a reference value, wherein the reference value is between 0V and 2V. For this purpose, the control circuit 158 controls the switching of the reception comparator 152 from a reception threshold value T2= -0.35V to a reception threshold value T4 of, for example, +0.35V by means of the signal sw _ th 2. The generated signal CA2 is output to the device 11. A change in the bus network of the bus system 1 should be recognized by comparing the signal CA2 with a reference value CA2_0, wherein the reference value CA2_0 is stored in at least one of the memory blocks 1112, 1122 in fig. 5. The identified change compared to the reference value CA2_0 indicates network steering.

Thus, the signal CA2 is evaluated by at least one of the evaluation blocks 1111, 1121. If the evaluation of at least one of the evaluation blocks 1111, 1121 results in the presence of a manipulation, the associated manipulation reaction block 1112, 1122 causes at least one corresponding reaction. The reaction may be, for example: the communication control device 11 interrupts the transmission of the transmission signal TxD. Alternative or additional reactions may be, for example: the transmitting/receiving device 12 interrupts the transmission of the frame 450 onto the bus 40. Alternative or additional reactions may be, for example: the communication control device 11 transmits at least one error frame 48. Alternative or additional reactions may be, for example: the communication control device 11 signals the microcontroller of the superordinate control device of the subscriber station 10 about the manipulation.

In this way, manipulations in the bus system 1 can be reliably recognized. Further, the manipulation may be responded to as necessary.

Fig. 7 shows the structure of the second comparator 152 as an example. The first comparator 151 may be constructed in the same manner.

According to fig. 7, the second comparator 152 has a run type setting unit 1520, a two-stage circuit (zweistufistie Schaltung) having a first input difference pair (eingingsdiffernzpaar) 1521, a second input difference pair 1522, and first to third current mirrors (strompsiegel) 1525, 1526, 1527, and an output buffer 1528. The output buffer 1528 drives the output signal CA2.

The operation type setting unit 1520 is manipulated by the manipulation circuit 158 with the switching signal sw _ th 2. This switching signal sw _ th2 switches the comparator 152 in accordance with the type of operation with which the receiver electrode 153 receives the signals CAN _ H, CAN _ L, to be precise, which are explained as described above.

The two-stage circuit in fig. 7 has the following elements, namely: first to fifth current sources I1, I2, I3, I4, I5; and first and second transistors TR1, TR2 forming a first input difference pair 1521; a resistance Rdiff; first and second current collecting resistors RC1, RC2; the third and fourth transistors TR5, TR6 function as emitter followers (emitteformers); the fifth and sixth transistors TR7, TR8 function as level switches (level shifters)); seventh and eighth transistors TR9, TR10 forming a second input difference pair 1522; a first current mirror 1525 having transistors TR11, TR 12; a second current mirror 1526 having transistors TR13, TR 14; a third current mirror 1527 having transistors TR15, TR 16. These transistors TR1, TR2, TR5, TR7, TR8 are npn bipolar transistors in the example of fig. 7. These transistors TR9, TR10 are pnp bipolar transistors in the example of fig. 7. These transistors TR11, TR12, TR13, TR14, TR15, TR16 are field effect transistors in the example of fig. 7. These transistors TR11, TR12, TR13, TR14 of the first and second current mirrors 1525, 1526 are in the example of fig. 7 NMOS transistors, in particular normal blocking n-channel MOSFETs (metal-oxide-semiconductor field effect transistors). The transistors TR15, TR16 of the third current mirror 1527 are in the example of fig. 7 PMOS transistors, in particular normal blocking p-channel MOSFETs (metal-oxide-halide-feldfektransististoren).

The two-stage circuit of fig. 7 is supplied with the voltage CAN _ SUPPLY via the connection 43. Each of these current collecting resistors RC1, RC2 is connected at one of its ends to a connection terminal 43. The collector of the transistors TR5, TR6 is also connected to the connection 43. Furthermore, a fifth current source I5 and a third current mirror 1527 having transistors TR15, TR16 are connected to connection 43. A fifth current source 15 feeds a second input difference pair 1522 consisting of seventh and eighth transistors TR9, TR 10.

The first current source I1 is connected to the ground line and to the emitter of the first transistor TR1 at the other end thereof and to one end of the resistor Rdiff. The second current source I2 is connected to the ground line and at its other end to the emitter of the second transistor TR2 and to the other end of the resistor Rdiff. The current sources I1, I2 set the operating point for the transistors TR1, TR 2. Depending on the value of the switching signal sw _ th2, the reception threshold T2 or the reception threshold T4 is set by the current sources I1, I2 and the resistance Rdiff, as explained in the foregoing table 2.

The base of the third transistor TR5 is connected to the connection between the first transistor TR1 and the first current collecting resistor RC 1. The base of the fourth transistor TR6 is connected to the connection between the second transistor TR2 and the second current collecting resistor RC 2. The fifth transistor TR7 is connected with its own collector and its own base to the emitter of the third transistor TR 5. The sixth transistor TR8 is connected to the emitter of the fourth transistor TR6 with its own collector and its own base. The emitter of the third emitter TR5 is connected to a current source I3. The emitter of the fourth transistor TR6 is connected to the current source I4.

The base of the seventh transistor TR9 is connected to the connection between the fifth transistor TR7 and the third current source I3. The base of the eighth transistor TR10 is connected to the connection between the sixth transistor TR8 and the fourth current source I4. The emitters of the transistors TR9, TR10 are connected to the current source I5. The transistor T11 of the first current mirror is connected to the collector of the seventh transistor TR 9. The transistor T13 of the second current mirror is connected to the collector of the eighth transistor TR 10.

The transistor T12 of the first current mirror 1525 is connected between the transistor T15 of the third current mirror 1527 and the ground line. The transistor T14 of the second current mirror 1526 is connected between the transistor T16 of the third current mirror 1527 and the ground line. The output buffer 1522 is connected at its input to the transistor TR14 of the second current mirror and the transistor TR16 of the third current mirror.

In the example of fig. 5 to 7, the control circuit 158 is embodied as a transistor or has at least one transistor. The transistor is in particular an NMOS transistor. The abbreviation "NMOS" stands for n-channel MOSFET, where the abbreviation "MOSFET" stands for metal oxide field effect transistor. If the manipulation circuit 158 manipulates the operation type setting unit 1520 with the signal sw _ th2 having the value "high", the operation type setting unit 1520 sets the reception threshold T2 of fig. 4 as previously described.

This means that, according to fig. 5 to 7, the first comparator 151 provides, depending on the type of operation of the transmitting/receiving device 12, a signal CA1 which has been evaluated with different reception thresholds in the two communication phases of the message 45. Here, these signals S _1, S _2 are evaluated in the first comparator 151 by using the reception threshold T1 in the arbitration phase 451 and by using the reception threshold T3 in the data phase 452. Instead, for the second comparator 152: signal CA2 is evaluated with a reception threshold T2 in the arbitration phase 451 of message 45 and in the data phase 452 at least at a predetermined time TA, and with a reception threshold T4 only for times in the arbitration phase 451 of message 45 that are outside the predetermined time TA (fig. 4). If a signal sw _ th2 with a value "high" is applied to the operation type setting unit 1520, the second comparator 152 supplies a signal CA2, in which case the signals S _3, S _4 are evaluated by using the reception threshold T2. In contrast, the first comparator 151 provides, independently of the signal sw _ th2, in the arbitration phase 451, the signal CA1, in the case of which signal CA1 the signals S _1, S _2 are evaluated by using the reception threshold T1. In other words, the first comparator 151 provides an identification of the threshold value T1 in the arbitration phase 451, while the second comparator 152 provides either an identification of the threshold value T2 or an identification of the threshold value T4. The receive threshold T4 is enabled only if no arbitration has occurred in the arbitration phase 451. In particular, the receive threshold T4 is enabled only if arbitration ends in the arbitration phase 451, but there has not yet been a switch to the data phase 452.

In contrast, if the signal sw _ th2 on the operation type setting unit 1520 has the value "low", the second comparator 152 provides the signal CA2 in which case the signals S _3, S _4 are evaluated by using the reception threshold T4. In contrast, the first comparator 151 in turn supplies, independently of the signal sw _ th2, the signal CA1, in the case of which signal CA1 the signals S _1, S _2 are evaluated by using the reception threshold T1. In other words, the first comparator 151 provides identification of the threshold T1 and the second comparator 152 provides identification of the threshold T4.

In contrast, if the signal sw _ th1 has the value "low" at the operation type setting unit 1520 of the comparator 151, the first comparator 151 provides the signal CA1 in which case the signals S _1, S _2 are evaluated by using the reception threshold T3. In contrast, the second comparator 151 in turn supplies, independently of the signal sw _ th1, a signal CA2, in the case of which signal CA2 the signals S _3, S _4 are evaluated by using the reception threshold T2. In other words, the first comparator 151 provides identification of the threshold T3 and the second comparator 152 provides identification of the threshold T2.

By means of this embodiment of the receiving circuit 15, two different receiving thresholds of the receiving thresholds T1, T2, T3, T4 can be checked independently of one another and therefore also simultaneously or synchronously. In addition to this, by means of the control circuit 158, two of the reception thresholds T1, T2, T3, T4 can be switched between. In this way, the reception thresholds T1, T2 can be checked either independently of one another and simultaneously according to fig. 4, or the reception thresholds T1, T4 can be checked independently of one another and simultaneously according to fig. 4, or the reception thresholds T3, T2 can be checked independently of one another and simultaneously according to fig. 4.

Thus, the operation type setting unit 1520 sets the reception thresholds T2, T3 according to the currently required operation type (SLOW, FAST _ TX, FAST _ RX) of the transmission/reception apparatus 12 and/or the currently required operation type of the second comparator 152.

According to a first modification of the above embodiment, at least one of these evaluation blocks 1111, 1121 evaluates the signal CA2 not only by using the reference value CA2_0. Additionally, these evaluation blocks 1111, 1121 wherein the at least one evaluation block also evaluates the received signal RxD by using the reference value CA2_0. In this case, the point in time at which the signals CA2, rxD are detected in order to determine the network steering may be the same. Since the point in time at which the signals CA2, rxD are detected for determining the network handling is in the arbitration phase 451, the RxD signal has been created by using the reception threshold T1. The receive threshold T1 is typically at 0.7V, as described previously with reference to table 1. Thereby, it is possible to determine also more accurately: whether or not there is a maneuver. If the evaluation of at least one of the evaluation blocks 1111, 1121 results in the presence of a manipulation, the associated manipulation reaction block 1112, 1122 causes at least one corresponding reaction as described above.

According to the second modification of the foregoing embodiment, the signal sw _ th1 having the value "low" at the operation type setting unit 1520 sets the reception threshold T1 in the comparator 151, and the signal sw _ th1 having the value "high" sets the reception threshold T3 in the comparator 151. The signal sw _ th2 may be changed as described above.

According to the third modification of the foregoing embodiment, the signal sw _ th2 having the value "low" at the operation type setting unit 1520 sets the reception threshold T2 in the comparator 152 and the signal sw _ th2 having the value "high" sets the reception threshold T4 in the comparator 152. The signal sw _ th1 may be changed as described above.

Fig. 8 shows a transmission/reception apparatus 12A according to the second embodiment. The transmitting/receiving device 12A may be used in the bus system 1 of fig. 1 instead of the transmitting/receiving device 12.

The transmission/reception device 12A has a transmission module 1210 and a reception module 122. The transmission module 1210 is constructed in the same manner in four parts as the transmission module 121 according to the first embodiment. Therefore, only the differences from the first embodiment will be described next.

In contrast to the first exemplary embodiment, the transmit module 1210 is designed to generate the signals CAN _ H, CAN _ L for two communication phases 451, 452 on the bus 40, as described next with reference to fig. 9 to 12. Therefore, the transmission/reception apparatus 12A is in the SIC operation type in the arbitration stage 451. However, instead of this, the transmission module 1210 CAN generate the signals CAN _ H, CAN _ L at least temporarily for two communication phases 451, 452 on the bus 40 as described previously in accordance with fig. 3 and 4. In this case, the transmission/reception apparatus 12A is in the SLOW operation type in the arbitration phase 451.

Fig. 9 shows an example for a part of a digital transmission signal TxD, wherein the transmission module 121 receives the part of the digital transmission signal TxD from the communication control device 11 in an arbitration phase 451 and thereby generates signals CAN _ H, CAN _ L for the bus 40. In fig. 9, the transmission signal TxD transitions from the state LW (Low = Low) to the state HI (High = High) and back again to the state LW (Low = Low).

In the ideal case, the receive signal RxD is identical to the transmit signal TxD. In this ideal case, there is no transmission delay/running time, in particular via the bus 40, and there is no unexpected reception error.

As shown in more detail in fig. 10, the transmit module 121 CAN generate the signals CAN _ H, CAN _ L of fig. 10 for the bus cores 41, 42 in the operating type CAN SIC or CAN XL for the transmit signal TxD of fig. 9. In contrast to fig. 3, in the signal case of fig. 10, a state 403 (sic) is additionally present. This state 403 (sic) may be of different lengths, as shown by state 403_0 (sic) in the transition from state 401 (rec) to state 402 (dom) and by state 403_1 (sic) in the transition from state 401 (dom) to state 402 (rec). This state 403_0 (sic) is shorter in time than state 403_1 (sic). To generate a signal according to fig. 10, the transmit module 1210 is switched to the SIC run type (SIC mode).

CiA610-3 does not require passing through the short sic state 403 _0as per the standard for CAN XL, and this state depends on the implementation. Starting from the rising edge at the transmission signal TxD of fig. 8, the duration of the "long" state 403_1 (SIC) is specified as t _ SIC < 530ns in the CAN XL case, not only for the CAN SIC but also for the SIC operating type.

The transmit module 1210 is intended to adapt the impedance between the bus lines 41 (CANH) and 42 (CANL) in the "long" state 403_1 (sic) as well as possible to the characteristic wave resistance Zw of the used bus line. In this case, zw = 100 Ohm or 120 Ohm is applied. The adaptation prevents relaxation and thus allows operation at higher bit rates. For the sake of simplicity, the state 403 (sic) or the sic state 403 is always mentioned next.

Fig. 11 shows an example of a further part for a digital transmission signal TxD, which transmission module 1210 receives in a data phase 452 from communication control device 11 (fig. 1) and thus generates signals CAN _ H, CAN _ L for bus 40. In fig. 11, the transmission signal TxD is transformed from the state HI (High = High) to the state LW (Low = Low) and again to the state HI (High = High) a plurality of times, and so on.

As shown in more detail in fig. 12, the transmit module 1210 generates the signals CAN _ H, CAN _ L for the bus lines 41, 42 for the transmit signal TxD of fig. 10 in such a way that the state L0 is formed for the state LW (Low = Low). Further, the state L1 is formed for the state HI (High = High).

It is possible that for the two bus states L0, L1, at least temporarily, no dominant and recessive bus states are used, but instead a first bus state and a second bus state are used, wherein both bus states are driven. An example for such a bus system is the CAN XL bus system.

The receiving module 122 can also receive signals according to fig. 10 and 12 in the two different communication phases, namely the SIC operating type or arbitration phase 451 and the data phase 452. For this purpose, the receiving module 122 switches the receiving thresholds T1, T2, T3, T4 for the respective type of operation, as described previously with reference to the above-described embodiments.

The operation type setting unit 1537 thus handles: the reception thresholds T1, T2, T3, T4 are set according to the currently required operating type (SIC, FAST TX, FAST RX) of the transmitting/receiving device 12A and/or the operating type of the second comparator 152.

In addition, the transmission module 1210 is configured to improve the network handling evaluation and to transmit the signals CAN _ H, CAN _ L without the sic state 403 in the set range or bit of the arbitration phase 451. A first example for the set range is the range after arbitration in the arbitration phase 451 has ended but the data phase 452 has not yet terminated. A second example for the set range is the bit of the arbitration phase 451, in particular bit AL1 of fig. 2.

In the subscriber station 10, the communication control device 11, in particular the protocol controller 111 and/or the timer 113, ensures that: the subscriber station 10 is the only sender in the bus system 1. Thus, the communication control device 11, in particular the protocol controller 111 and/or the timer 113 checks: whether the arbitration in the arbitration phase 451 is finished. Furthermore, it is ensured that: the transmitting/receiving device 12A, in particular the transmitting module 1210, is in SIC operating mode.

If the transmitting/receiving device 12A transitions from the operating type of the data phase 452, i.e. Fast TX/Fast RX operating type, to the SIC operating type, the transmitting/receiving device 12A knows: the frame 450 is about to end. The transmission/reception device 12A, starting from the Fast TX operating type, is controlled by the communication control device 11, in particular the protocol controller 111 or the timer 113, in such a way that the transmission/reception device 12A also transmits the bit AL1 after the switch from the Fast TX operating type to the SIC operating type, as was mentioned above with reference to fig. 2. At the end of the AL1 bit, there is a rising edge in the transmit signal TxD at which the transmit module 1210 exceptionally produces an recessive state (rec) 402 without the sic state 403. In this set transition from state (dom) 401 to (rec) 402, the sic function is not used in the transmitting/receiving device 12A, in particular in the transmitting module 1210. Instead, only the transition 403_0 is generated or for the AL1 bit signals CAN _ H, CAN _ L, as shown in fig. 3.

During the "slow" arbitration phase (maximum 1 Mbit/s), no identification problems occur with the communication control devices 11, 21 of the bus system 1, in particular the protocol controller 111 or the timer 113, by transmitting without the state (sic) 403.

In the range or bit of the set arbitration phase 451 in which the transmission module 1210 transmits the signals CAN _ H, CAN _ L without the sic state 403, the network-typical relaxation behavior (auspr 228gen) is more intense, in particular at the falling edge of the signals CAN _ H, CAN _ L for the AL1 bit. Thus, the blocks 1111, 1121 can more easily recognize the change of the behavior of the bus 40 by the manipulation. In the set range or bit of the arbitration phase 451 in which the transmission module 1210 transmits the signals CAN _ H, CAN _ L without the state (sic) 403, the signal progression progresses as in the case of the classical CAN/CAN-FD.

Fig. 13 shows a transmitting/receiving apparatus 12B according to the third embodiment. This transmitting/receiving device 12B can be used in the bus system 1 of fig. 1 instead of the transmitting/receiving device 12A of fig. 8.

Unlike the above-described embodiment, the transmission/reception apparatus 12B has a protocol controller 159 configured to interpret a portion of the protocol of the frame 450. The protocol controller 159 has a reduced functional range compared to the protocol controller 111.

The protocol controller 159 is configured to determine, by means of the sending module 1210, a point in time for checking and sending the status (rec) 402 without the status (sic) 403 by means of the sending module 1210. In this regard, the protocol controller 159 monitors the received signal RxD. In the example of fig. 13, the protocol controller 159 monitors the output of the first comparator 151 for this purpose.

In this embodiment, the protocol controller 159 controls the transmission module 1210 in order to cause the transmission module 1210 to transmit the signals CAN _ H, CAN _ L without the state (sic) 403 in the range or bit of the set arbitration phase 451. The protocol controller 159 in particular controls the transmission module 1210 in accordance therewith at the falling edge of the signals CAN _ H, CAN _ L for the AL1 bit: state (sic) 403 is not produced or only transition 403_0 is produced.

In this way, too, the blocks 1111, 1121 can recognize the change of the behavior of the bus 40 by the manipulation, as described previously. Thus, at least one of these blocks 1113, 1123 may be utilized to trigger a desired reaction, as described above.

Fig. 14 shows a transmitting/receiving apparatus 12C according to the fourth embodiment. The transmitting/receiving device 12C can be used in the bus system 1 of fig. 1 instead of one of the transmitting/ receiving devices 12A, 12B of fig. 8 or 13.

Unlike the above-described embodiment, the transmission/reception device 12C has a logic block 160 connected to the outputs of the comparators 151, 152. The logic block 160 uses the signals CA1, CA2 of the comparators 151, 152 to identify changes in the signal profile of the differential voltage VDIFF. If both comparators 151, 152 are in good match (Matching), random distortions can therefore be eliminated (Verf 228lschung), which can be identified as intrusions or manipulations. However, these comparators 151, 152 are set to different ones of the receive thresholds T1, T2, T3, T4, as previously described in accordance with table 2.

The following possibilities arise through the logical operation of the signals CA1, CA2 of the comparators 151, 152 set to different ones of the reception thresholds T1, T2, T3, T4: four different states are detected. The logic block 160 thus constitutes a 2-bit AD converter.

These blocks 1111, 1121 therefore evaluate the output signal CA _160 of the logic block 160. The output signal CA _160 contains information of the received signal RxD and the signal CA2.

The blocks 1111, 1121 can also recognize in this way, as described above, changes to the behavior of the bus 40 through manipulation. Thus, at least one of these blocks 1113, 1123 may be utilized to trigger a desired reaction as described above.

Fig. 15 shows a transmitting/receiving apparatus 12D according to the fifth embodiment. This transmitting/terminating device 12D can be used in the bus system 1 of fig. 1 instead of one of the transmitting/ receiving devices 12A, 12B, 12C of fig. 8 or 13 or 14.

Unlike the previous embodiment, the transmission/reception apparatus 12D has a run type detection block 161 connected to the output of the first comparator 151. The operation type detection block 161 uses the signal CA1 of the comparator 151 for detecting the operation type of the transmission/reception apparatus 12D.

The run type detection block 161 is configured to determine the point in time for checking and transmitting the state (rec) 402 without the state (sic) 403 by means of the transmission module 1210. For this purpose, the run type detection block 161 monitors the received signal RxD. In the example of fig. 15, the operation type detection block 161 monitors the output of the first comparator 151 for this purpose.

In this variant, the operation type detection block 161 controls the transmission module 1210 in order to cause the transmission module 1210 to transmit the signals CAN _ H, CAN _ L without the sic state 403 within the at least one bit or set range of the arbitration phase 451. In particular, the at least one bit of the arbitration phase 451 is an AL1 bit, so that at least in the case of a falling edge of the signals CAN _ H, CAN _ L no or only a shortened state (sic) 403 is transmitted for the AL1 bit.

In this way, these blocks 1111, 1121 can recognize the change of the behavior of the bus 40 by the manipulation as described above. Thus, at least one of these blocks 1113, 1123 may be utilized to trigger the desired reaction as described above.

Fig. 16 shows a receiving circuit 150 for the transmitting/receiving device 12 or 12A, 12B, 12C, 12D according to the sixth embodiment. This receiving circuit 150 can be used in the bus system 1 of fig. 1 instead of the receiving circuit 15 of fig. 6.

Unlike the first embodiment, the receiver electrode 153 has a first voltage divider 1535, a second voltage divider 1536, a first switching unit Sw1, a second switching unit Sw2, a third switching unit Sw3, and an operation type setting unit 1537 in the example of fig. 16. The operation type setting unit 1537 may be the same as the manipulation circuit 158 of the foregoing embodiment. The first and second voltage dividers 1536, 1537 are each supplied with the same voltage of the bus bias source 154, in particular 2.5V for the recessive state 402 (fig. 3 or fig. 10).

The first and second voltage dividers 1535 and 1536 are resistive or resistive voltage dividers, respectively.

The first voltage divider 1535 has first to seventh resistors R _ CH1_ a to R _ CH7_ a for the bus signal CAN _ H. The first resistor R _ CH1_ a is connected at one of its ends to the bus line 41 (CANH). The first resistor R _ CH1_ a is connected at its other end in series with a parallel circuit consisting of the second resistor R _ CH2_ a and a series circuit consisting of the third and fourth resistors R _ CH3_ a, R _ CH4_ a. The end of the fifth resistor R _ CH5_ a is connected at the junction of the resistors R _ CH3_ a, R _ CH4_ a. In addition, the fourth resistor R _ CH4_ a is connected at its other end to an end of the sixth resistor R _ CH36_ a. These resistors R _ CH5_ a, R _ CH6_ a are connected at their other ends to a seventh resistor R _ CH7_ a. The resistor R _ CH7_ a is connected at the other end thereof to the first switching unit Sw1. The switching unit Sw1 is also connected to ground and therefore to the connection 44.

In addition, the voltage divider 1535 has eighth to twelfth resistors R _ CL1_ a to R _ CL5_ a for the bus signal CAN _ L. The eighth resistor R _ CL1_ a is connected at one of its ends to the bus line 42 (CANL). The resistor R _ CL1_ a is connected at its other end in series with a parallel circuit composed of a ninth resistor R _ CL2_ a and a series circuit composed of tenth and eleventh resistors R _ CL3_ a, R _ CL4_ a. The end of the twelfth resistor R _ CL5_ A is connected at the junction of the resistors R _ CL3_ A and R _ CL4_ A. In addition, the resistors R _ CL2_ a, R _ CL4_ a, and R _ CL5_ a are connected to the connections of the resistors R _ CH2_ a, R _ CH4_ a, and R _ CH6_ a, respectively, at the connections thereof.

A first input of the first comparator 151 is connected to the junction between said first and second resistors R _ CH1_ a, R _ CH2_ a. A second input of the first comparator 151 is connected to the junction between said eighth and ninth resistors R _ CL1_ a, R _ CL2_ a.

The reception threshold T1 of fig. 4 is set by the resistance path through the resistor R _ CH7_ a to the ground line (connection 44). In order to be able to switch to the reception threshold T3 according to table 2 above, a first switching unit Sw1 is provided, which can be operated with an operation type setting unit 1537, as described in more detail below. In this case, the logic circuit 1222 is configured such that the two comparator signals CA1, CA2 are forwarded to the driver 1221 in the arbitration phase 451. In the data phase 452, only the comparator signal CA1 is forwarded to the driver 1221.

The receiving module 122 of fig. 1 always evaluates the signals CAN _ H, CAN _ L simultaneously or synchronously with two receiving thresholds, i.e. either with the receiving thresholds T1, T2 or with the receiving thresholds T1, T4 or with the receiving thresholds T3, T2. It is also possible that: as described in more detail below, the reception thresholds T1, T3 are evaluated simultaneously or synchronously. Furthermore, the two simultaneously or synchronously evaluated reception thresholds are evaluated independently of one another.

The second divider 1536 in fig. 16 has first to seventh resistors R _ CL1_ B to R _ CL7_ B for the bus signal CAN _ H. The first resistor R _ CL1_ B is connected to the bus line 41 (CANL) at one end thereof. The first resistor R _ CL1_ B is connected at its other end in series with a parallel circuit consisting of the second resistor R _ CL2_ B and a series circuit consisting of the third and fourth resistors R _ CL3_ B, R _ CL4_ B. The end of the fifth resistor R _ CL5_ B is connected at the junction of the resistors R _ CL3_ B, R _ CL4_ B. Further, the fourth resistor R _ CL4_ B is connected at the other end thereof to the end of the sixth resistor R _ CL6_ B. These resistors R _ CL5_ B, R _ CL6_ B are connected at the other end thereof to the end of the resistor R _ CL7_ B. The resistor R _ CL7_ B is connected to the second switching unit Sw2 at the other end thereof. The switching unit Sw2 is also connected to ground and therefore to the connection 44.

In addition, the second voltage divider 1536 has eighth to fourteenth resistors R _ CH1_ B to R _ CH7_ B for the bus signal CAN _ L. The first resistor R _ CH1_ B is connected at one end to the bus line 42 (CANH). The first resistor R _ CH1_ B is connected at its other end in series with a parallel circuit consisting of a ninth resistor R _ CH2_ B and a series circuit consisting of tenth and eleventh resistors R _ CH3_ B, R _ CH4_ B. The end of the twelfth resistor R _ CH5_ B is connected at the junction of the resistors R _ CH3_ B and R _ CH4_ B. The end of the thirteenth resistor R _ CH6_ B is connected at the junction of the resistors R _ CH2_ B, R _ CH4_ B. Further, the resistors R _ CH5_ B and R _ CH6_ B are connected to the ends of the resistors R _ CH7_ B at their own connections. The resistor R _ CH7_ B is connected to the third switching unit Sw3 at the other end thereof. The switching unit Sw3 is also connected to the ground line and thus to the connection 44.

The first input of the second comparator 152 is connected to the junction between the first and second resistors R _ CH1_ B, R _ CH2_ B. A second input of the second comparator 152 is connected to the junction between the eighth and ninth resistors R _ CL1_ B, R _ CL2_ B.

If these switching units Sw2, sw3 are switched accordingly, the reception threshold T2 or T4 or T3 of fig. 4 is set to the ground line or the resistance path with the resistance R _ CL7_ B to the connection terminal 44 or to the ground line or the resistance path with the resistance R _ CH7_ B to the connection terminal 44.

For example, the following applies: if the switching unit Sw2 is switched so that the path from the resistor R _ CL7_ B to the connection terminal 44 is conductive, and the switching unit Sw3 is switched so that the path from the resistor R _ CH7_ B to the connection terminal 44 is non-conductive, the reception threshold T2 of fig. 4 is set.

If the switching unit Sw2 is switched so that the path from the resistance R _ CL7_ B to the connection terminal 44 is not conductive in this example, and the switching unit Sw3 is switched so that the path from the resistance R _ CH7_ B to the connection terminal 44 is conductive, the reception threshold T4 of fig. 4 is set.

Thus, the receiving circuit 150 can be manipulated for setting the receiving thresholds T1 to T4 for the comparators 151, 152, as described earlier with reference to table 2.

It is additionally possible that: the reception threshold T3 of fig. 4 is set in the second voltage divider 1536. For this reason, the switching unit Sw2 is switched such that the path from the resistor R _ CL7_ B to the connection terminal 44 is not conductive, and the switching unit Sw3 is switched such that the path from the resistor R _ CH7_ B to the connection terminal 44 is not conductive. In this case, the receiving circuit 150 or the receiving module 122 can check these receiving thresholds T1, T3 simultaneously and/or synchronously. If switching between fewer receive thresholds than previously described is required, the receive circuit 150 and/or the receive pole 153 may have a different number of switch units than the three switch units Sw1, sw2, sw 3. It is possible in particular for the receiver pole 153 to have only the switching unit Sw1. Thus, the switching between two reception thresholds can be done in case of one of the voltage dividers 1535, 1536 and the reception threshold is fixedly set in case of the other voltage divider 1535, 1536. Any other combination can be envisaged.

Depending on which reception thresholds should be switched between with at least one switching unit Sw1, sw2, sw3, the at least one switching unit Sw1, sw2, sw3 can be connected to the ground line by a resistor instead.

The circuit of the resistors in the resistor network of the voltage divider 1535, 1536 is symmetrically constructed.

To comply with the requirements of the input resistor Rin on CANH and CANL, the resistive voltage division paths of these voltage dividers 1535, 1536 have half values due to the double structure. In this case, the following applies: rin _ CANH and Rin _ CANL =25 kOhm \8230; 50 kOhm. Typically, an input resistance Rin of 37.5 kOhm is selected for the connection (Pin) for the signal CAN _ H and for the connection (Pin) for the signal CAN _ L. In this case, the resistive paths of the voltage dividers 1535, 1536 have the following specific configuration. The path from CANH through the resistor R _ CH1_ a of the first voltage divider 1535 to ground or to the connection 44 of CAN _ GND has a resistance value of about 2 × 37.5 kOhm. The path from the CANH through the resistor R _ CH1_ B of the second voltage divider 1536 to ground or to the connection 44 for CAN _ GND has a resistance value of about 2 × 37.5 kOhm. The path from CANL through the resistor R _ CL1_ a of the first voltage divider 1535 to ground or to the connection 44 for CAN _ GND has an approximate resistance value. The path from CANL through the resistor R _ CL1_ B of the second voltage divider 1536 to ground or to the connection 44 of CAN _ GND has a resistance value of about 2 × 37.5 kOhm.

According to table 1 above, the tolerance (+/-100 mV) required in the case of the thresholds T2, T3 and in particular also in the case of the threshold T4 is half the tolerance (+/-200 mV) in the case of the threshold T1, so that the resistance of the first voltage divider 1535 for the first comparator 151 may be configured differently from the resistance of the second voltage divider 1536, for example. The resistance of the second voltage divider 1536 has a larger and/or higher semiconductor area, in particular silicon area (Si area), than the resistance of the first voltage divider 1535. This results in a smaller divergence of the reception thresholds than is required according to table 1.

However, if the first voltage divider 1535 is also configured to switch between the thresholds T1, T3 as previously described, the resistance of the second voltage divider 1536 may be configured, for example, for the second comparator 152 as the resistance of the first voltage divider 1535. Therefore, the semiconductor area, particularly, the silicon area (Si area) of the resistor of the second voltage divider 1536 is, for example, the same as the semiconductor area, particularly, the silicon area (Si area) of the resistor of the first voltage divider 1535. Thus, the dispersion of the reception thresholds is the same.

In the example of fig. 16, these switching units Sw1, sw2, sw3 are transistors, particularly NMOS transistors, respectively. The abbreviation "NMOS" stands for n-channel MOSFET, where the abbreviation "MOSFET" stands for metal oxide field effect transistor. If the operation type setting unit 1537 operates the switch unit Sw1 with a signal having a value "high", the switch unit Sw1 is conductive or closed. In this case, the resistor R _ CL7_ a is connected to the ground line (connection terminal 44). As described above, the reception threshold T1 of fig. 4 is set by the resistance path of the resistance R _ CL7_ a to the ground line.

If the operation type setting unit 1537 operates the switching unit Sw1 with a signal having a value "low", the switching unit Sw1 is not conductive or off. In this case, the resistor R _ CH7_ a is disconnected or turned off from the ground line (connection terminal 44) and sets the reception threshold T3 of fig. 4. The same applies correspondingly: the switching units Sw2, sw3 are signally operated by the operation type setting unit 1537 for setting the reception thresholds T2, T3, T4 of fig. 4 as described previously.

In association with the comparators 151, 152 and the digital output signals CA1, CA2 generated by these comparators, the same contents as those described previously for the first embodiment and with reference to the table apply for the NMOS transistor as the switching unit Sw1 or Sw2 or Sw 3.

Thus, the two voltage dividers 1535, 1536 form a dual substructure. These voltage dividers 1535, 1536 divide these bus voltages generated by the signals CAN _ H, CAN _ L into values that CAN be processed by the comparators 151, 152.

By means of the dual substructure of the receiver pole 150, two different reception thresholds of the reception thresholds T1, T2, T3, T4 can be checked independently of one another and therefore also simultaneously or synchronously. In addition thereto, switching between two of the reception thresholds T1, T2, T3, T4 can be controlled by the operation type setting unit 1537 by means of the switching unit Sw1. In this way, the reception thresholds T1, T2 according to fig. 4 can be checked either independently of one another and simultaneously or the reception thresholds T1, T4 according to fig. 4 can be checked independently of one another and simultaneously. Two of the four reception thresholds T1, T2, T3, T4 can be switched to the third reception threshold as needed.

The operation type setting unit 1537 thus sets the reception thresholds T1, T2, T3, T4 of the transmitting/receiving device 12 (SLOW, FAST _ TX, FAST _ RX) or of the transmitting/receiving device 120 (SIC, SLOW, FAST _ TX, FAST _ RX) according to the currently required operation type.

According to the seventh embodiment, the receiving subscriber station 10 performs a check in view of network steering by using the differential voltage VDIFF. In this case, the transmitting/receiving device 12, 22, 12A, 12B, 12C, 12D used is switched to the operating type FAST RX in the data phase 452. At the termination of the operating type FAST RX, the transmitting/receiving means 12, 22, 12A, 12B, 12C, 12D used also expect the AL1 bit of fig. 2 from the transmitting subscriber station 10, 30, which indicates the end of the frame 450 in the data phase 452. The check for network steering can therefore be carried out at the end of the AL1 bit, since a check for the reception threshold T2 (OOB function) is no longer necessary here. As previously described, the check is performed at the falling edge at the end of the AL1 bit in the differential voltage VDIFF, as previously described in the preceding embodiments.

In this case, however, the receiving subscriber station 10 must already store the reference value CA2_0 for every possible sender of the bus system 1, i.e. every other subscriber station 10, 30, in order to be able to evaluate the behavior of the bus 40 with respect to network handling. This also means that: the receiving subscriber station 10, in the case of a number n of subscriber stations 10, 20, 30 in the bus system 1, must carry out a check with regard to the network management for n-1 subscriber stations. In contrast, as described for the preceding exemplary embodiments, the check with the transmitting subscriber station 10 takes significantly less time, computing power and memory space.

In general, the detection of network manipulations and their processing or reaction to detected network manipulation(s) applies: the detection and its processing or reaction can be used at least partially in all bus systems. In particular, all the following possibilities can be combined with one another here.

The detection of network manipulation may be determined thereafter: in which user station 10, 20, 30 of the bus system 1 the network actuation is checked by evaluating the signal profile of the bus voltage, in particular the differential voltage VDIFF. In this case, an advantageous solution is: as described in the first to sixth exemplary embodiments, the check is carried out only at the transmitting subscriber stations 10, 20, 30 of the bus system 1. Alternatively, as described in the seventh exemplary embodiment, the check is carried out on all receiving subscriber stations 10, 20, 30 of the bus system 1. However, this alternative is less advantageous, since the check should be carried out on n-1 subscriber stations 10, 20, 30 and is therefore significantly more costly.

The detection of the network manipulation can be differentiated according to the number of comparators to be considered for evaluating the signal profile of the bus voltage, in particular of the differential voltage VDIFF. It is possible that: only the comparator is used which performs a check of the reception threshold T2 (OOB). In the previously described example, this is the second comparator 152. Alternatively, in addition to the reception comparator that performs the check of the reception threshold T2 (OOB), a reception comparator that uses the reception threshold in the case of typical VDIFF =0.7V is used. This is the preferred solution, as described in the previous embodiments. However, it is also possible: in addition, additional comparators are also used more cost-effectively than the two mentioned receiving comparators.

The evaluation of network steering can be distinguished according to the following: where the output signal of the at least one comparator is forwarded, as described in the first and the following embodiment(s). According to a first example, the at least one output signal is only fed to the (leiten) protocol controller 111. According to a second example, the at least one output signal is only fed to a Timer (Timer) 112, which operates the protocol controller 111. According to a third example, the at least one output signal is not only conveyed to the protocol controller 111 but also to a Timer (Timer) 112.

Furthermore, a distinction can be made between the identification of the points in time at which the network manipulations are detected and then evaluated, which can also be referred to as evaluation points in time of the manipulation(s). According to a first example, the evaluation time point is determined with a reduced functional range using a protocol controller 159, wherein the protocol controller 159 is arranged in the transmitting/receiving device 12, as described in the fourth embodiment. According to the second example, the evaluation time point is detected by the block 161 for detecting the operation type of the transmission/reception apparatus 12, as described in the fifth embodiment.

A distinction can also be made in this regard between the evaluation of the network manipulation as follows: an additional connection (Pin) is used on the transmitting/receiving device 12 for the signal to be evaluated. The already existing connections (Pin) on the transmitting/receiving device 12 can be used in a multiplexing method, as described in the first embodiment.

All of the previously described embodiments of the transmitting module 121, 1210, receiving module 122, receiving circuit 15, 150, subscriber stations 10, 20, 30 of the bus system 1 and of the methods carried out therein of the transmitting/receiving devices 12, 22, 12A, 12B, 12C, 12D according to the exemplary embodiments and modifications thereof can be used individually or in all possible combinations. In addition, the following modifications can be envisaged in particular.

The previously described bus system 1 according to the embodiments is described in terms of a bus system based on the CAN protocol. However, the bus system 1 according to the embodiments may alternatively be another communication network in which case the signals are transmitted as differential signals. Advantageous, but not mandatory conditions are: in the case of the bus system 1, exclusive, conflict-free access by the user stations 10, 20, 30 to the bus 40 is ensured at least for the determined time period.

The bus system 1 according to the exemplary embodiments and their modifications is in particular a CAN bus system or a CAN-HS bus system or a CAN FD bus system or a CAN SIC bus system or a CAN XL bus system. However, the bus system 1 may be a further communication network in which the signals are transmitted as differential signals and serially via the bus 40.

Thus, the functionality of the exemplary embodiments described above CAN be used, for example, in the transmission/ reception devices 12, 22, 12A, 12B, 12C, 12D, wherein these transmission/reception devices CAN be operated in the CAN bus system or CAN-HS bus system or CAN FD bus system or CAN SIC bus system or CAN XL bus system.

The number and arrangement of the subscriber stations 10, 20, 30 in the bus system 1 according to the first and second embodiment and their modifications is arbitrary. In particular, only the subscriber station 10 or only the subscriber station 30 is present in the bus system 1 of the exemplary embodiment.

Claims (19)

1. -transmitting/receiving means (12, 12a, 12c:

a first comparator (151) for evaluating signals (CAN _ H, CAN _ L) received from a bus (40) of the bus system (1) with a first reception threshold (T1; T3);

a second comparator (152) for evaluating signals (CAN _ H, CAN _ L) received from the bus (40) with a second reception threshold (T2) or a manipulation recognition reception threshold (T4), wherein the reception thresholds (T1, T2, T4) used by the comparators (151) are different, and wherein the second reception threshold (T2) is set for determining: whether a communication on the bus (40) is in a first communication phase (451) or a second communication phase (452) for sending a frame (450) onto the bus (40);

a driver (1221) for driving a digital receive signal (RxD) to a communication control means (11) of the subscriber station (10;

a logic circuit (1222) for forwarding an output signal (CA 1) of the first comparator (151) and an output signal (CA 2) of the second comparator (152) to the driver (1221) if a second reception threshold (T2) is set in the second comparator (152) and communication on the bus (40) is in the first communication phase (451), and for forwarding only the output signal (CA 1) of the first comparator (151) to the driver (1221) if a manipulation recognition reception threshold (T4) is set in the second comparator (152); and

a connection (C2) for outputting the output signal (CA 2) of the second comparator (152) to the communication control device (11).

2. The transmitting/receiving device (12,

wherein the input of the second comparator (152) is low-pass filtered with less intensity than the input of the first comparator (151), wherein the output of the second comparator (152) is low-pass filtered with less intensity than the output of the first comparator (151).

3. The transmitting/receiving device (12.

4. -a transmitting/receiving device (12, 12a, 12c, 12d) according to claim 1 or 2, wherein said connections (C2) are connections operable in a multiplexing method for at least two functions of said transmitting/receiving device (12.

5. The transmitting/receiving device (12, 12a, 12c, 12d) according to any one of the preceding claims, wherein it has a steering circuit (158) for switching the reception threshold of the second comparator (152) from the second reception threshold (T2) to the maneuver identification reception threshold (T4) for a predetermined duration in a frame (450) transmitted onto the bus (40) of the bus system (1).

6. The transmit/receive device (12B) as claimed in any of the preceding claims, wherein the transmit/receive device (12B) furthermore has a protocol controller (159) which is configured to detect a predetermined point in time in the frame (450) at which the steering circuit (158) should perform a steering for switching the receive threshold of the second comparator (152).

7. The transmit/receive device (12D) as claimed in any of the preceding claims, wherein the transmit/receive device (12D) furthermore has a run type detection block (161) which is configured to detect, in the frame (450), a predetermined point in time at which the steering circuit (158) should perform a steering for switching the receive threshold of the second comparator (152).

8. The transmitting/receiving device (12, 12a, 12c) according to any one of the preceding claims, wherein said steering circuit (158) performs a steering for switching the reception threshold of said second comparator (152) if said transmitting/receiving device (12, 12a, 12b, 12d) is the recipient of said frame (450.

9. The transmitting/receiving device (12, 12a, 12c, 12d) as claimed in any one of the preceding claims, wherein the transmitting/receiving device furthermore has a voltage divider (1533) connected to the bus (40) for providing signals (CAN _ H, CAN _ L) received from the bus (40) for the first comparator (151; 152) and for the second comparator (152; 151), wherein the first and second comparators (151, 152) are connected to the voltage divider (1533) in such a way that the signals (CAN _ H, CAN _ L) are evaluated synchronously.

10. The transmitting/receiving device (12, 12a, 12c, 12d) according to any one of claims 1 to 8, wherein said transmitting/receiving device has:

a first voltage divider (1535) for setting the first reception threshold (T1) or a third reception threshold (T3), wherein the first comparator (151) is connected to the first voltage divider (1535) for evaluating a signal (CAN _ H, CAN _ L) received from a bus (40) of the bus system (1) with the first or third reception threshold (T1; T3) set by the first voltage divider (1535);

a second voltage divider (1536) for setting the second reception threshold (T2) or a manipulation-recognition reception threshold as a fourth reception threshold (T4), wherein the second comparator (152) is connected to the second voltage divider (1536) for evaluating the signals (CAN _ H, CAN _ L) received from the bus (40) with the second or fourth reception threshold (T2; T4) set by the second voltage divider (1536), and

wherein the first voltage divider (1535) and the second voltage divider (1536) are respectively connected to the bus (40).

11. -the transmitting/receiving device (12, 12a, 12c, 12d) of claim 10, wherein said first voltage divider (1535) and said second voltage divider (1536) have a circuit consisting of a resistance on which said first comparator (151) and second comparator (152) are connected, and wherein said first voltage divider (1535) and said second voltage divider (1536) have a resistance on which said first comparator (151) and second comparator (152) are connected

Wherein the first comparator (151) and the second comparator (152) evaluate the signals (CAN _ H, CAN _ L) synchronously.

12. The transmitting/receiving apparatus (12.

13. The transmitting/receiving apparatus (12, 12a, 12c, 12d) according to claim 12, wherein at least one switching unit (Sw 1; sw2, sw 3) is arranged for connecting said voltage divider (1535, 1536) to ground or for disconnecting said voltage divider (1535, 1536) from ground.

14. The transmitting/receiving device (12.

15. For a subscriber station (10:

the transmitting/receiving device (12

A communication control device (11.

16. The subscriber station (10.

17. The user station (10,

wherein the communication control device (11,

wherein the timer (112) is also designed to evaluate an output signal (CA 2) of the second comparator (152) from the connection (C2).

18. The subscriber station (10: the subscriber stations (10, 20, 30) access the bus (40) of the bus system (1) exclusively and in a collision-free manner.

19. Method for identifying manoeuvres in a serial bus system (1), wherein the method is performed with a transmitting/receiving device (12 12a, 12b, 12c, 12d) of a user station (10:

evaluating signals (CAN _ H, CAN _ L) received from a bus (40) of the bus system (1) by means of the first comparator (151) with a first reception threshold (T1);

evaluating the signals (CAN _ H, CAN _ L) received from the bus (40) by means of a second comparator (152) with a second reception threshold (T2) or a manipulation-recognition reception threshold (T4), wherein the reception thresholds (T1, T2, T4) used by the comparators (151; 152) are different, and wherein the second reception threshold (T2) is set for determining: whether a communication on the bus (40) is in a first communication phase (451) or a second communication phase (452) for sending a frame (450) onto the bus (40);

forwarding, by the logic circuit (1222), an output signal (CA 1) of the first comparator (151) and an output signal (CA 2) of the second comparator (152) to the driver (1221) if a second reception threshold (T2) is set in the second comparator (152) and the communication on the bus (40) is in the first communication phase (451), and forwarding, by the logic circuit (1222), only the output signal (CA 1) of the first comparator (151) to the driver (1221) if the manipulation recognition reception threshold (T4) is set in the second comparator (152); and is

-a communication control means (11) for driving a digital receive signal (RxD) to said subscriber station (10; and is provided with

Outputting the output signal (CA 2) of the second comparator (152) to the communication control device (11) on the connection (C2).

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