Switchable CAN Encoding for Faster Data Transfer Without Bus Conflicts
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Solution Overview
Problem
The existing CAN protocols face limitations in transmitting large data blocks efficiently, leading to delays and impaired real-time properties, especially when bit-by-bit arbitration is required, and existing solutions either compromise on data integrity or interrupt communication.
Innovation Solution
A modified data transmission method called AC-CAN, which uses alternate coding techniques and adjusts bus clock rates to increase data transmission rates while maintaining error detection and network consistency, allowing for faster data transfer without disrupting standard CAN operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bit-by-bit arbitration is used to ensure non-destructive transmission and real-time properties, then data transmission reliability is improved, but data transmission speed deteriorates due to the relatively low bit rate
Solution Approach 1:
The message is divided into two distinct parts: an arbitration field transmitted using standard CAN bit-by-bit arbitration for reliability, and a data field transmitted using alternative coding at higher bit rates for speed. This segmentation allows each part to use the most appropriate transmission method for its requirements.
Solution Approach 2:
The system dynamically switches between two coding methods (standard CAN coding and alternative coding) depending on the part of the message being transmitted. The coding method is not fixed but adapts based on whether the current transmission phase is arbitration or data transfer.
2Speed
If the bit rate is increased by reducing the duration of individual bits, then data transmission speed is improved, but the uniform picture of bus status among all bus participants deteriorates
Solution Approach 1:
The message transmission is segmented into two phases with different bit rates: the arbitration field uses standard bit durations to ensure all participants maintain a uniform picture of bus status, while the data field uses reduced bit durations for faster transmission where arbitration is no longer needed.
Solution Approach 2:
The arbitration field is transmitted first using standard coding to establish bus ownership and ensure all participants have synchronized status information before the high-speed data transmission begins.
3Speed
If communication interface is switched to another for transferring large data blocks, then data transmission speed is improved, but communication with CAN protocols is interrupted and real-time properties deteriorate
Solution Approach 1:
The invention merges two different communication approaches into a single unified method: standard CAN arbitration for reliability and alternative high-speed coding for data transfer. This combination eliminates the need to switch between separate communication interfaces while maintaining both speed and protocol continuity.
Solution Approach 2:
The CAN protocol communication continues uninterrupted throughout the entire message transmission process. The alternative coding is applied within the CAN framework rather than requiring a switch to a different communication interface, ensuring continuous and reliable CAN protocol operation.
4Quantity of substance
If larger data blocks are transmitted via CAN domain, then data capacity is improved, but transmission time increases due to the relatively low bit rate
Solution Approach 1:
The bit rate parameter is changed during message transmission: standard bit rates are used for the arbitration field, while significantly higher bit rates are used for the data field. This parameter change allows larger data blocks to be transmitted in less time without compromising the arbitration process.
Data Source
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Figure 3a~3b
Figure 3c
AI summary
The invention relates to a method and to a device for transferring data in a network having at least two data processing units, which exchange messages by means of the network, wherein the exchanged messages have a logical structure according to CAN specification ISO 11898-1, wherein the bits are encoded as per the method according to CAN standard ISO 11898-1 for at least one first specifiable range within the exchanged messages, and wherein the bits are encoded as per a method deviating from CAN standard ISO 11898-1 for at least one second specifiable range within the exchanged messages if a switching condition is present.