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DE-102024210747-A1 - Method for transmitting data frames using a communication controller

DE102024210747A1DE 102024210747 A1DE102024210747 A1DE 102024210747A1DE-102024210747-A1

Abstract

The invention relates to a method (100) for transmitting data frames using a communication controller (2) in a serial vehicle bus system (3), comprising: - Assigning (101) a respective unique identifier to each node (4) in the serial vehicle bus system (3), - Providing (102) a mapping specification, wherein priority values of different data frames are mapped to access priorities of the serial vehicle bus system (3) according to the mapping specification, - Transmission (103) of the data frames using the communication controller (2), wherein the transmission of each data frame is controlled by the communication controller (2) based on the assigned identifiers and the provided mapping specification.

Inventors

  • Herbert Leuwer
  • Thomas WOLLENHAUPT
  • Christoph Hufen

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241108

Claims (10)

  1. Method (100) for transmitting data frames using a communication controller (2) in a serial vehicle bus system (3), comprising: - Assigning (101) a unique identifier to each node (4) in the serial vehicle bus system (3), - Providing (102) a mapping specification, wherein priority values of different data frames are mapped to access priorities of the serial vehicle bus system (3) according to the mapping specification, - Transmitting (103) the data frames using the communication controller (2), wherein the transmission of the respective data frames is controlled by the communication controller (2) based on the assigned identifiers and the provided mapping specification.
  2. Procedure (100) according to Claim 1 , characterized in that the method (100) further comprises: - tracking a last transmitted identifier value, wherein a transmission of a respective node (4) by the CAN XL communication controller is only permitted if a current identifier value of the respective node (4) exceeds the tracked last transmitted identifier value.
  3. Method (100) according to one of the preceding claims, characterized in that for controlling the transmission, transmission possibilities are assigned to the data frames on the basis of CAN XL priority fields of the data frames, in particular using a Medium Utilization State Tracking algorithm.
  4. Method (100) according to one of the preceding claims, characterized in that the method (100) further comprises: - assigning a unique payload type to each data frame, wherein the transmission of the respective data frames is further controlled on the basis of the assigned payload type.
  5. Procedure (100) according to Claim 4 characterized in that the assigned payload type at least indicates whether a given data frame is an Ethernet or a non-Ethernet data frame.
  6. Method (100) according to one of the preceding claims, characterized in that frame padding is performed depending on the length of a respective data frame, wherein the respective data frame is extended so that it is at least 512 bits long.
  7. Method (100) according to one of the preceding claims, characterized in that the serial vehicle bus system (3) is arranged and used in a vehicle (1).
  8. Computer program (20), comprising instructions which, when the computer program (20) is executed by a computer (10), cause it to execute the method (100) according to one of the preceding claims.
  9. Device (10) for data processing, which is configured to perform the method (100) according to one of the Claims 1 until 7 to execute.
  10. Computer-readable storage medium (15), comprising instructions which, when executed by a computer (10), cause it to perform the steps of the procedure (100) according to one of the Claims 1 until 7 to execute.

Description

The invention relates to a method for transmitting data frames using a communication controller. The invention further relates to a computer program, a device, and a storage medium for this purpose. State of the art Ethernet networks are typically built using Ethernet bridges connected via point-to-point links. This is the most suitable connectivity method for medium- to high-speed connections above 100 Mbps with reasonably long cable lengths. Each host or termination point connected to the bridged network requires its own bridge port. However, for many applications, a low-speed connection of around 10 Mbps is sufficiently fast, and bus topologies can be more cost-effective than point-to-point connections because only one bridge port is needed to connect many hosts. The original CSMA-based bus technology for 10Base-T can only detect access collisions (CSMA/CD), but not avoid them, resulting in very low utilization of the available bus bandwidth. To overcome this limitation, the IEEE introduced the 10Base-T1S standard, which provides collision-free multiple access technology for a single twisted-pair cable. However, this technology requires a centralized master to coordinate access to the medium. Neither bus technology currently has a standardized access priority that allows high-priority traffic preferential use of the transmission medium. CAN XL enables the encapsulation of Ethernet frames into a single CAN XL frame by defining a dedicated payload type in the CAN XL frame header. Arbitration on the medium prevents collisions (CSMA/CA). Therefore, no data frames are lost, and the available bandwidth of the medium can be fully utilized. Another advantage of CAN XL as a link-layer technology is its multi-service capability: both Ethernet transport and content-based standard CAN addressing can coexist on the same bus medium. In typical CAN XL designs, the CAN XL communication controller is connected to the software via message buffers. The receive message buffers can be connected to data frame filters to support the filtering of CAN message identifiers (acceptance field in the case of CAN XL). Since no CAN identifier is required to describe the message content during Ethernet-over-CAN XL transmission, the 32-bit CAN XL accept field includes a reduced 32-bit Ethernet MAC address to support hardware MAC address filtering. The 8-bit virtual CAN identifier (VCID) includes a reduced version of the 12-bit Ethernet VLAN identifier to support Ethernet ingress filtering. These two filtering mechanisms are inherently permeable, necessitating post-filtering in software using the full 48-bit MAC address and the full 12-bit VLAN identifier of the encapsulated Ethernet frame. The aforementioned functions are specifically performed in a software-implemented CAN-to-Ethernet gateway: the software receives the CAN XL frame, determines the payload type, and forwards the Ethernet frame to its destination, which can be either an Ethernet relay function in a bridge or an Ethernet termination point. This software-implemented CAN-to-Ethernet gateway between the Ethernet relay function and the media increases system complexity, raises the latency of an Ethernet bridge, and may reduce the effective throughput of a bridge. Furthermore, current CAN XL standards do not define mechanisms for fair bandwidth allocation or access priority. Disclosure of the invention The invention relates to a method with the features of claim 1, a computer program with the features of claim 8, a device with the features of claim 9, and a computer-readable storage medium with the features of claim 10. Further features and details of the invention will become apparent from the respective dependent claims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the computer program, the device, and the computer-readable storage medium according to the invention, and vice versa, so that a reciprocal reference is always possible with regard to the disclosure of the invention. The invention relates in particular to a method for transmitting data frames using a communication controller, in particular a CAN XL communication controller, in a serial vehicle bus system, in particular a CAN XL bus system, comprising: - Assigning a unique identifier to each node in the serial vehicle bus system, wherein the nodes are in particular data processing devices such as computers, microcomputers or electronic control units, especially in a vehicle, - Providing a mapping specification, such as a mapping table, wherein priority values of various data frames are mapped to access priorities of the serial vehicle bus system according to the mapping specification, wherein in particular priority values of data frames, especially Ethernet frames, are mapped to an access priority specified in the priority field of a CAN XL frame, - Transmission of the data frames using the communica