Serial Bus Subscriber Station Data Type Fields for Flexible Communication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing serial bus systems, such as CAN and CAN FD, struggle to support additional functions like safety, security, and QoS while maintaining or increasing data rates, as their frame identifier mapping is not flexible enough and does not scale well.
Innovation Solution
A subscriber station for a serial bus system introduces a field for data type within the frame, allowing for a modular communication protocol that separates data transport from additional functions like safety and security, ensuring flexibility and expandability without changing the frame format.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flat mapping of frame identifier and content is used in Classical CAN and CAN FD, then arbitration is possible, but the mapping does not scale well and is not flexible enough for additional functions
Solution Approach 1:
The frame structure is segmented into distinct fields: a first field (0-3 bits) for priority/arbitration and a second field (4-7 bits) for data type identification. This segmentation allows the arbitration field to remain simple while the data type field provides flexibility for additional functions like safety, security, and QoS without increasing overall frame complexity.
Solution Approach 2:
A data type field is introduced as an intermediary between the arbitration field and the payload data. This intermediary field enables rich functionality classification (safety, security, QoS, etc.) without requiring changes to the arbitration mechanism or the basic frame structure, thus maintaining compatibility while adding versatility.
2Adaptability or versatility
If more functions (safety, security, QoS) are added to the bus system, then communication capabilities are enhanced, but data rate may decrease
Solution Approach 1:
Only 8 bits are used for the data type field, which is sufficient to classify all required data types (safety, security, QoS, etc.) without wasting bandwidth. This partial action approach provides adequate functionality while minimizing overhead and maintaining high data rates.
Solution Approach 2:
The data type field serves multiple functions simultaneously: it enables safety-critical communication, security authentication, QoS classification, and future extensibility. This multi-functionality is achieved within a fixed 8-bit structure that does not increase frame length or reduce data transmission rate.
3Adaptability or versatility
If the frame format is changed to support new functions, then flexibility is improved, but compatibility with existing systems is lost
Solution Approach 1:
The new data type field is nested within the existing CAN FD frame structure as an extension of the data field. This nesting allows new functionality to be added without altering the fundamental frame format, ensuring that existing CAN and CAN FD systems can coexist and communicate while new systems can utilize the enhanced data type classification.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a subscriber station (10; 30) for a serial bus system (1) and to a method for communicating in a serial bus system (1). The subscriber station (10; 30) includes a communication control device (11; 31) for controlling a communication of the subscriber station (10; 30) with at least one other subscriber station (10; 20; 30) of the bus system (1), and a transceiver device (12; 32) for transmitting a transmission signal (TXD) generated by the communication control device (11; 31) to a bus (40) of the bus system (1); for a message (45) that is exchanged between subscriber stations (10, 20, 30) of the bus system (1), the bit time (t_bt) of a signal transmitted to the bus (40) in the first communication phase (451) differs from a bit time (t_bt) of a signal transmitted in the second communication phase (452); the communication control device (11; 31) is configured to generate the transmission signal (TXD) according to a frame (450; 450_1; 4500) in which, in addition to a field (ID) indicating the priority of the message (45), a field for a data type (DT) is provided, and the communication control device (11; 31) is configured to write, into the field for the data type (DT), a value indicating what type of information is located in a data field (455) of the frame (450; 450_1; 4500).