Method for operating a communication system, network device, synchronization module, communication system and vehicle

Abstract

The invention relates to a method for operating a communication system (10) comprising network devices (16) that are interconnected via at least two networks according to respective communication protocols (20, 22) through respective hybrid interfaces (26), wherein the method comprises the following steps: receiving a message (30) by a real-time control unit (24) of a source network device (16) of the communication system (10), wherein the message (30) comprises payload data for transmission to a destination network device (16) of the communication system (10); selecting the communication protocol (20, 22) for transmission of the message (30) to the destination network device (16) by the real-time control unit (24) of the source network device (16); providing the message (30) and the selection to a hybrid interface (26) of the source network device (16) by the real-time control unit (24) of the source network device (16);Sends the message (30) to a hybrid interface (26) of the destination network device (16) using the selected communication protocol (20, 22) through the hybrid interface (26) of the source network device (16); receives the message (30) through the hybrid interface (26) of the destination network device (16).

Description

[0001] The invention relates to a method for operating a communication system, a network device for a communication system, a synchronization module, a communication system, and a vehicle comprising a communication system.

[0002] In modern vehicles, communication protocols such as Ethernet and FlexRay are used to transmit data between various electronic control units (ECUs). Time-Sensitive Networking (TSN) was developed to meet the requirements of real-time communication in Ethernet-based networks. FlexRay, on the other hand, is a proven protocol that offers deterministic latency but operates with lower bandwidth.

[0003] To leverage the respective advantages of both protocols, implementations of TSN and FlexRay already exist in automotive networks. However, these protocols operate independently, which makes it difficult to utilize their combined benefits. A major problem with TSN is that high network load can lead to latency issues and inconsistent transmission times. These limitations make TSN alone less suitable for safety-critical applications where guaranteed deterministic latency is essential.

[0004] DE 10 2016 209 370 A1 describes a method for transmitting data packets between an Ethernet network and a time-controlled bus network.

[0005] CN 115 766 860 A describes a vehicle-mounted network communication technology, a data transmission method, a TSN node and a computer-readable storage medium.The data transmission process comprises the following steps: when a FlexRay data frame sent from a source device in a first FlexRay network is received, the FlexRay data frame is converted into a TSN data frame after it has been determined that a transmission slot of the FlexRay data frame is a static slot; the TSN data frame is transmitted along a TSN data frame transmission path in a deterministic time delay manner; and when the TSN data frame is transmitted to the last TSN node on the transmission path, the TSN data frame is restored to the FlexRay data frame and sent to a destination device in a second FlexRay network, as indicated by the FlexRay data frame, so that the TSN network is compatible with the FlexRay network and the deterministic time delay in the data transmission process is ensured.

[0006] DE 10 2012 211 303 A1 describes a communication system and a procedure.

[0007] DE 10 2013 114 355 A1 describes a method, a device and a computer program for the digital transmission of messages.

[0008] DE 10 2014 218 152 A1 describes a communication device and a method for communication between an operator interface of a machine and a control device of the machine.

[0009] DE 10 2013 217 259 A1 describes a mode switching of a control unit between diagnostic bus and external Ethernet connection.

[0010] DE 10 2004 008 910 A1 describes a method and a communication system for transmitting information in a motor vehicle.

[0011] US 2008 / 0247544A1 describes authentication in an audiovisual system with multiple signal paths.

[0012] The present invention is based on the objective of enabling the combined use of several network protocols.

[0013] The problem is solved by the subject matter of the independent patent claims. Advantageous further developments of the invention are described by the dependent patent claims, the following description, and the figures.

[0014] A first aspect of the invention relates to a method for operating a communication system. The communication system comprises network devices that are interconnected via hybrid interfaces using at least two communication protocols. In other words, the communication system includes the network devices, each of which has a hybrid interface. The communication system has at least two networks, each with its own communication protocol, through which messages can be exchanged between the network devices. The network devices transmit a message using one of the at least two communication protocols. The hybrid interfaces each have a separate interface for each of the communication protocols.

[0015] The procedure for operating the described communication system comprises the following steps. A first step involves a real-time control unit of a source network device of the communication system receiving a message. In other words, a message to be sent via the communication system is provided to the source network device. The message contains payload data for transmission to a destination network device of the communication system. In other words, the source network device receives the message that it intends to transmit via the communication system to the destination network device. The message may, for example, be provided by a module connected to the source network device.

[0016] A further step involves the real-time control unit of the source network device determining predefined characteristics of the message. In other words, the received message is examined by the real-time control unit of the source network device and checked against the predefined characteristics. These predefined characteristics might relate to, for example, the message length or its urgency. The characteristics can be specified in such a way as to be suitable for selecting the appropriate communication protocol.

[0017] A further step involves selecting the communication protocol for sending the message to the destination network device, based on the message characteristics determined by the source network device's real-time control unit. In other words, the determined characteristics form the basis for which of the available communication protocols should be used to transmit the message to the destination network device. For example, the real-time control unit may be configured to specify which communication protocol is preferred for which characteristics.

[0018] In a further step, the message, along with the selection of the communication protocol to be used, is transmitted or signaled to the hybrid interface of the source network device by the source network device's real-time control unit. In other words, after the communication protocol to be used has been determined, the message, along with the selection, is transmitted to the hybrid interface of the source network device so that it can forward the message to the destination network device. The hybrid interface of the source network device may have separate interfaces for sending and / or receiving the message according to the communication protocols.

[0019] In a further step, the message is sent to a hybrid interface of the target network device via the selected communication protocol, or, alternatively, via the hybrid interface of the source network device using the selected communication protocol (i.e., according to the selected communication protocol). In other words, the message is adapted according to the selected communication protocol and transmitted to the hybrid interface of the source network device via the communication system using that protocol.

[0020] A further step involves receiving the message through the hybrid interface of the target network device. In other words, the hybrid interface of the target network device is also connected via at least two communication protocols of the communication system and configured to receive messages.

[0021] A further step involves sending a provisioning message to the real-time control unit of the target network device through the hybrid interface of the target network device.

[0022] It is intended that the selection of the communication protocol for sending the message depends on the load on at least one of the communication protocol networks. In other words, the selection of the communication protocol for sending the message from the source network device to the destination network device depends on the current load on one or both of the communication protocols. For example, it may be intended that one of the communication protocols is designated or preferred for a specific characteristic. However, it may be that the desired characteristic of the communication protocol can no longer be guaranteed at a certain level of network load.For this reason, it may be designed so that if the preferred communication protocol is overloaded or the secondary communication protocol is underutilized, the less congested protocol is selected for sending the message. In FlexRay networks, high utilization can lead to increased latency because a prioritized communication mechanism is used in its static and dynamic segments. If a large number of higher-priority messages are transmitted, lower-priority messages can experience significant delays. This can affect real-time control systems that require predictable response times for proper operation. Similarly, Time-Sensitive Networking (TSN) can also be affected by high network utilization.The time-sensitive scheduler of TSN networks assigns specific time slots to each message to make latency predictable. However, if the overall network load exceeds the capacity of these allocated time slots, it can lead to increased latency and jitter in communication, which can negatively impact the performance of real-time systems.

[0023] The invention offers the advantage that messages can be exchanged between network devices of the communication system using at least two communication protocols. This makes it possible to select the communication protocol depending on the properties of the message.

[0024] A further development of the invention provides that the at least two communication protocols include FlexRay. This is a deterministic, high-speed bus system frequently used in automotive and industrial applications. The FlexRay communication protocol offers features such as fault tolerance and high data rates, making it suitable for message transmission in safety-critical applications.

[0025] A further development of the invention provides that the at least two communication protocols include Time-Sensitive Networking (TSN). TSN is a set of standard extensions for Ethernet that enable real-time communication. It offers precision and reliability and is therefore ideally suited for demanding applications in fields such as automotive.

[0026] TSN can provide various types of data prioritization and enables the simultaneous transmission of multiple data streams with guaranteed latency and bandwidth.

[0027] A further development of the invention provides that the selection of the communication protocol for sending the message depends on a required message latency. In other words, it can be stipulated that certain latency requirements must be met. The selection of the communication protocol can take these latency requirements into account and choose the appropriate communication protocol accordingly. This further development of the invention thus provides for an adaptive selection of the communication protocol, depending on the required message latency. Specific latency requirements are considered in order to select the suitable communication protocol. Latency plays a crucial role, especially in real-time communication. FlexRay and Time-Sensitive Networking (TSN) have different latency values.TSN is a standard for real-time communication in Ethernet networks and supports low latency of just a few microseconds. FlexRay, on the other hand, offers higher latency of several hundred microseconds. Adaptive protocol selection ensures compliance with required latency values ​​by choosing the most suitable protocol with the lowest latency. If a message needs to be transmitted with very low latency, TSN is preferred. Conversely, if higher latency is acceptable, FlexRay can be used.

[0028] A further development of the invention provides that the selection of the communication protocol for sending the message depends on the message size. For example, one communication protocol might be more suitable for sending large messages than another. In FlexRay, the maximum message size depends on the data rate at which a message is sent. There are two data rates: the fast rate for real-time communication and the slow rate for less critical communication requirements. The maximum message size at the fast rate is 254 bytes, while at the slow rate it is 196 bytes. In TSN, the maximum message size depends on the characteristics of the network and the devices used. Unlike FlexRay, TSN does not have a fixed upper limit for the message size.Instead, the maximum size is determined by the available bandwidth and the number of active devices on the network. FlexRay is not ideal for exchanging large amounts of data because it has a fixed upper limit on the maximum message size. TSN, on the other hand, may be better suited for use cases with larger messages due to its flexibility and scalability, especially in environments with variable communication patterns and a large number of devices. TSN is designed to support a wide range of data rates and message sizes, making it attractive for use in applications that need to transfer large amounts of data.

[0029] A further development of the invention provides that the selection of the communication protocol for sending the message depends on the message's priority. For example, it may be the case that some message content is security-relevant and therefore must be transmitted with priority. In FlexRay, there are two types of communication segments: static and dynamic segments. In the static segment, a fixed number of slots are reserved for transmitting high-priority messages, while in the dynamic segment, a mechanism is implemented to select higher-priority messages when multiple messages compete within a given timeframe. The priority of a message in FlexRay is determined by its assignment to a specific communication slot, with higher priorities being reserved for slots with lower numbers. In TSN, however, a more flexible and dynamic mechanism for prioritizing messages is used.The IEEE 802.1Q Avbridged / Short Bridge (ASB) protocol defines the Time-Aware Scheduler (TAS), which establishes schedules for sending messages, taking into account a range of priority levels. By using TAS, TSN can create a deterministic schedule that ensures critical, higher-priority messages are sent before less critical ones. FlexRay is well-suited for real-time control applications where communication must be predictable and deterministic. The static allocation of higher-priority slots ensures that critical messages are always sent first. TSN, on the other hand, is more flexible and dynamic and is better suited for use cases with variable communication patterns.By using the Time-Aware Scheduler, TSN can support a wide variety of priority levels, making it attractive for use in more demanding real-time control applications.

[0030] A further development of the invention provides that the method includes synchronizing the hybrid interface using a synchronization module. In many applications, TSN and FlexRay networks work together to provide a variety of functions. For example, in an automobile, both a TSN network and a FlexRay network can be used to enable communication between different control units and subsystems. In such systems, it is important that the data is correctly synchronized and that real-time requirements are met.

[0031] For use cases or application situations that may arise during the procedure and are not explicitly described here, it may be provided that, according to the procedure, an error message and / or a request for user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0032] A second aspect of the invention relates to a network device comprising a real-time control unit and a hybrid interface. The network device is configured to perform a method of the first aspect of the invention. The real-time control unit is configured to receive a message intended for transmission to a target network device of the communication system. The real-time control unit is configured to determine predetermined features of the message and, based on these features, to select a communication protocol for transmitting the message to the target network device. The real-time control unit is configured to provide the message and the selected communication protocol to a hybrid interface.The hybrid interface is set up to send the message via the selected communication protocol and / or to receive a message via the selected communication protocol.

[0033] A third aspect of the invention relates to a synchronization module which is configured to synchronize network devices of the second aspect of the invention.

[0034] A fourth aspect of the invention relates to a communication system comprising network devices that are interconnected via hybrid interfaces over at least two networks according to respective communication protocols. The communication system is configured to perform a method of the first aspect of the invention.

[0035] The network device and the synchronization module can include a data processing device or a processor circuit configured to perform an embodiment of the method according to the invention. For this purpose, the processor circuit can include at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). In particular, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an NPU (Neural Processing Unit) can be used as the microprocessor. Furthermore, the processor circuit can include program code configured to perform the embodiment of the method according to the invention when executed by the processor circuit. The program code can be stored in a data memory of the processor circuit. The processor circuit can, for example,based on at least one circuit board and / or at least one SoC (System on Chip).

[0036] The invention also includes further developments of the network device, the synchronization module, and the system according to the invention, which have features already described in connection with the further developments of the method according to the invention. For this reason, the corresponding further developments of the network device, the synchronization module, and the system according to the invention are not described again here.

[0037] The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

[0038] The invention also includes combinations of the features of the described embodiments. The invention therefore also includes realizations that each exhibit a combination of the features of several of the described embodiments, provided that the embodiments have not been described as mutually exclusive.

[0039] The following are exemplary embodiments of the invention described. This is illustrated by: Fig. 1. A schematic representation of a communication system; Fig. 2 a schematic representation of an interaction of the hybrid interface, the synchronization module and the real-time control unit of the communication protocol; and Fig. 3 a schematic representation of the sequence of a procedure for operating a communication system.

[0040] The exemplary embodiments described below are preferred embodiments of the invention. In these exemplary embodiments, the described components each represent individual features of the invention, which can be considered independently of one another and each further develops the invention independently. Therefore, the disclosure is intended to include combinations of features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0041] In the figures, identical reference symbols denote functionally equivalent elements.

[0042] Fig. Figure 1 shows a schematic representation of a communication system.

[0043] The communication system 10 can be arranged in a vehicle 12 to enable communication between vehicle modules 14 of the vehicle 12. The communication system 10 can include network devices 16, which can be connected to vehicle modules 14 of the vehicle 12. The network devices 16 are connected via a hybrid communication system 10 for transmitting messages 30. The hybrid communication protocol 18 can include at least two communication protocols 20, 22. The communication protocols 20, 22 can include, for example, FlexRay or CAN. The network devices 16 can be connected to the communication protocols 20, 22 via hybrid interfaces 26 of the respective communication protocols 20, 22. The hybrid interfaces 26 are configured to send and / or receive messages 30 according to the respective communication protocols 20, 22.The communication protocols 20 and 22 can differ from one another and have their own advantages and disadvantages, so their suitability may depend on the message 30 to be sent. To select the communication protocol 20 or 22, the respective network device 16 has a real-time control unit 24. The real-time control unit 24 is configured to receive a message 30. The message 30 may, for example, be provided by the vehicle module 14 of the vehicle 12 connected to the network device 16 and addressed to another of the vehicle modules 14. The real-time control unit 24 of the source network device 16 is configured to examine the received message 30 and determine predefined characteristics of the message 30. These characteristics may, for example, relate to the content of the message 30 or the method of sending the message 30.The real-time control unit 24 can, for example, determine the priority of the message 30 to be sent. Based on these characteristics, the real-time control unit 24 can select the communication protocol 20, 22 of the hybrid communication protocol 18 to be used for transmission. The message 30 and the selected communication protocol 20, 22 can be provided by the real-time control unit 24 to the hybrid interface 26 of the source network device 16. The hybrid interface 26 is configured to convert the message 30 according to the selected communication protocol 20, 22 and send it to the addressed destination network device 16 via the communication protocol 20, 22. The destination network device 16 also has the hybrid interface 26, through which it can receive the message 30 via the communication protocol 20, 22.The hybrid interface 26 can unpack message 30 and provide it to the real-time control unit 24 of the target network device 16. The real-time control unit 24 of the target network device 16 can then provide message 30 to the connected vehicle module 14 of the vehicle 12.

[0044] To enable synchronization, the communication system 10 can have a synchronization module 28 which can synchronize the hybrid interfaces 26 of the network devices 16 of the communication system 10 with each other.

[0045] Fig. Figure 2 shows a schematic representation of an interaction between the hybrid interface, the synchronization module and the real-time control unit of the communication protocol.

[0046] The hybrid structure of the communication system 10 eliminates the problem of potential latency issues with TSN under high network load, as FlexRay acts as a reliable transmission channel for time-critical data. The proposed communication system 10 comprises a hybrid communication interface 26, a real-time control unit 24 (RTCU), and a synchronization module 28. These components work together to classify, control, and synchronize messages 30 according to priority and requirement, enabling optimal transmission of both high-priority and bandwidth-intensive messages 30.

[0047] This hybrid communication protocol 18 is ideally suited for use in highly connected vehicles 12, particularly for autonomous driving applications, where both real-time control and large amounts of data must be processed in real time. Another area of ​​application is advanced driver assistance systems (ADAS), which require safety-critical real-time responses. A further area is connected infotainment systems, which require high bandwidth but are less time-critical.

[0048] This hybrid communication protocol 18 enables enhanced real-time capability. While TSN already offers real-time communication, latency issues can arise under high network load. Combining it with FlexRay eliminates these latency problems, as time-critical data is transmitted over the deterministic FlexRay network. The protocol dynamically adapts to varying network conditions to ensure optimal performance at all times, thus improving flexibility and adaptability. Integrated fault tolerance and redundancy mechanisms significantly increase system resilience, resulting in greater reliability.

[0049] The communication system 10 for the hybrid communication protocol 20, 22 is shown. The developed protocol consists of three main components. The hybrid communication interface is responsible for receiving and forwarding data packets that comply with both TSN and FlexRay standards. It includes mechanisms for converting TSN messages 30 into the FlexRay format and vice versa to ensure seamless communication. Additionally, the interface has a prioritization logic that classifies incoming messages 30 based on their time criticality and bandwidth requirements.

[0050] The real-time control unit 24 (RTCU) acts as a central control element, determining the priority of messages 30 and distributing them accordingly across the communication protocols 20 and 22. Critical messages 30 requiring guaranteed latency are preferentially transmitted via FlexRay, while less time-critical but bandwidth-intensive messages 30 are routed via TSN. The RTCU algorithm dynamically determines which messages 30 are prioritized based on current requirements and the network state. The synchronization module 28 ensures synchronization between the TSN and FlexRay networks. It uses a central clock source to minimize clock drift and ensures that all transmitted data packets are correctly synchronized.The synchronization module 28 continuously monitors the transmission times and paths and intervenes in the event of inconsistencies to restore synchronization.

[0051] The protocol employs several control mechanisms to optimize real-time communication. One of these mechanisms involves message classification and prioritization. Upon entering the system, messages are automatically classified according to their priority. High-priority messages (e.g., brake control signals) are sent via FlexRay to leverage the protocol's deterministic nature. Lower-priority messages (e.g., multimedia data) are routed via TSN. The RTCU algorithm dynamically determines which messages are prioritized based on current demands and the network state.

[0052] One of the control mechanisms involves load balancing. To maximize network efficiency, the RTCU distributes messages 30 evenly across both protocols, depending on their utilization. In situations of high network load, the RTCU can automatically redirect certain messages 30 between TSN and FlexRay to avoid bottlenecks.

[0053] One of the control mechanisms concerns fault tolerance and redundancy. The protocol offers integrated error handling, where messages 30 that were transmitted erroneously on one channel are automatically sent over the other channel.

[0054] This improves the overall reliability and fault tolerance of the system. Synchronization mechanisms are provided. The synchronization module 28 uses time-stamping and PTP (Precision Time Protocol) within the TSN to ensure data consistency across both networks. It ensures that all control units in the vehicle 12 have a common time base to optimize synchronization.

[0055] Fig. Figure 3 shows a schematic representation of the process of operating a communication system.

[0056] The in Fig. The procedure described in point 3 can, for example, be carried out by the method described in Fig. 1. The communication system 10 shown will be carried out.

[0057] A first step S1 of the procedure can include the receipt of a message 30 by a real-time control unit 24 of a source network device 16 of the communication system 10. The message 30 can contain payload data for transmission to a destination network device 16 of the communication system 10.

[0058] A second step S2 can include the determination of predefined features of message 30 by the real-time control unit 24 of the source network device 16.

[0059] A third step S3 can include a selection of the communication protocol 20, 22 for sending the message 30 to the target network device 16 depending on the determined characteristics of the message 30 by the real-time control unit 24 of the source network device 16.

[0060] A fourth step S4 can include the provision of message 30 and the selection of communication protocol 20, 22 to a hybrid interface 26 of the source network device 16 by the real-time control unit 24 of the source network device 16.

[0061] A fifth step S5 can include sending the message 30 to a hybrid interface 26 of the target network device 16 via the selected communication protocol 20, 22 through the hybrid interface 26 of the source network device 16.

[0062] A sixth step S6 can include receiving message 30 through the hybrid interface 26 of the target network device 16. A seventh step S7 can include providing message 30 to the real-time control unit 24 of the target network device 16 through the hybrid interface 26 of the target network device 16.

[0063] An eighth step S8 can include the provision of message 30 to a vehicle module 14 of the vehicle 12 by the real-time control unit 24 of the target network device 16.

[0064] The present invention relates to communication protocols 20, 22 in the automotive industry, in particular a hybrid communication protocol 18 that integrates Time-Sensitive Networking (TSN) and FlexRay in a single real-time control unit 24 to enable deterministic and high-bandwidth data transmission for safety-critical applications. The invention relates to a hybrid communication protocol 18 that combines the real-time capability of FlexRay with the high bandwidth and flexibility of TSN. This hybrid communication protocol 18 enables the integration of both communication protocols 20, 22 in the real-time control unit 24, which ensures synchronous and deterministic communication between different vehicle modules 14.

[0065] The focus of the invention is to process TSN and FlexRay combined in a single real-time control unit 24 in order to take advantage of both communication protocols 20, 22 for real-time and high-bandwidth applications.

[0066] While TSN can exhibit latency issues under high network load, FlexRay acts as a backup to ensure deterministic transmission for safety-critical applications. This duality is lacking in current state-of-the-art solutions, which instead focus on a single network framework or specific control strategies.

[0067] The communication system 10 includes a special synchronization module 28 that uses PTP and time-stamping to ensure synchronization between TSN and FlexRay.

[0068] The RTCU's dynamic algorithm, which distributes messages 30 between TSN and FlexRay according to their priority and network conditions, ensures additional flexibility.

[0069] The hybrid structure of the hybrid communication protocol 20, 22 eliminates the problem of potential latency issues with TSN under high network load, as FlexRay acts as a reliable transmission channel for time-critical data. The proposed solution comprises a hybrid communication interface, a real-time control unit 24 (RTCU), and a synchronization module 28. These components work together to classify, control, and synchronize messages 30 according to priority and requirement, enabling optimal transmission of both high-priority and bandwidth-intensive messages 30.

[0070] Overall, the examples show how the use of different communication protocols can be provided.

Claims

[1] Method for operating a communication system (10) comprising network devices (16) connected to each other via hybrid interfaces (26) over at least two networks according to respective communication protocols (20, 22), the method comprising the following steps: - Receiving a message (30) by a real-time control unit (24) of a source network device (16) of the communication system (10), wherein the message (30) includes payload data for transmission to a destination network device (16) of the communication system (10); - Determination of predefined features of the message (30) by the real-time control unit (24) of the source network device (16); - Selection of the communication protocol (20, 22) for sending the message (30) to the destination network device (16) depending on the determined characteristics of the message (30) by the real-time control unit (24) of the source network device (16); - Provision of the message (30) and selection to a hybrid interface (26) of the source network device (16) by the real-time control unit (24) of the source network device (16); -Sending the message (30) to a hybrid interface (26) of the destination network device (16) according to the selected communication protocol (20, 22) through the hybrid interface (26) of the source network device (16); - Receiving the message (30) through the hybrid interface (26) of the destination network device (16); and - Providing the message (30) to the real-time control unit (24) of the target network device (16) through the hybrid interface (26) of the target network device (16), characterized by , that the selection of the communication protocol (20, 22) for sending the message (30) depends on the current utilization of at least one network of communication protocols (20, 22). [2] Method according to claim 1, characterized bythat at least two communication protocols (20, 22) include Flexray. [3] Method according to claim 1 or 2, characterized by that at least two communication protocols (20, 22) include at least one Time-Sensitive Networking standard. [4] Method according to any one of the preceding claims, characterized by , that the selection of the communication protocol (20, 22) for sending the message (30) depends on a required latency of the message (30). [5] Method according to any one of the preceding claims, characterized by , that the selection of the communication protocol (20, 22) for sending the message (30) depends on the size of the message (30). [6] Method according to any one of the preceding claims, characterized by , that the selection of the communication protocol (20, 22) for sending the message (30) depends on a priority of the message (30). [7] Method according to any one of the preceding claims, characterized by , that the procedure includes synchronization of the network devices (16) of the communication system (10) by a synchronization module (28). [8] Network device (16), characterized by , that the network device (16) comprises a real-time control unit (24) and a hybrid interface (26) to perform a method according to any one of the preceding claims 1 to 7. [9] Synchronization module (28), characterized by , that the synchronization module (28) is configured to synchronize network devices (16) according to claim 8. [10] Communication system (10), characterized by , that the communication system (10) comprises network devices (16) which are interconnected via at least two networks according to respective communication protocols (20, 22) through respective hybrid interfaces (26) and are configured to perform a method according to one of claims 1 to 7. [11] Vehicle (12) comprising a communication system (10) according to claim 9.

Images