CAN Bus Subscriber Station Coding Device Arbitration Time Reduction
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Solution Overview
Problem
The CAN bus system's arbitration field limits the maximum data rate due to the need for each bit to be propagated to and from all subscriber stations, making it difficult to increase the Baud rate without sacrificing unique prioritizing and non-destructive arbitration characteristics.
Innovation Solution
A subscriber station with a coding device that allocates predetermined voltage levels to bit combinations, allowing multiple bits to be coded in a single bit time, thereby reducing the arbitration time while maintaining prioritizing and non-destructive arbitration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the Baud rate is increased to improve data transmission speed, then the transmission rate improves, but the arbitration time increases because each bit must be propagated to and from all subscriber stations
Solution Approach 1:
Multiple bits are merged into a single bit time for transmission during the arbitration field. Instead of transmitting each bit sequentially with propagation delays, the coding device combines multiple bits into one transmitted bit, eliminating the need for repeated propagation cycles and significantly reducing arbitration time while maintaining high transmission speeds
Solution Approach 2:
The patent changes the coding parameter by allocating different voltage levels to represent different bit combinations. This allows multiple bits to be encoded in a single bit time by varying the voltage level, enabling faster transmission without increasing arbitration time
2Productivity
If multiple bits are coded in a single bit time to reduce arbitration time, then the transmission rate improves, but the complexity of the coding device increases
Solution Approach 1:
The coding device uses voltage level parameter changes to encode multiple bits. By allocating specific voltage levels to represent different bit combinations, the device achieves efficient encoding without requiring complex processing logic, maintaining relative simplicity while improving transmission rate
Solution Approach 2:
The patent replaces sequential bit-by-bit mechanical propagation with an electrical voltage level-based coding system. This substitution allows parallel encoding of multiple bits into single bit times, reducing arbitration time while the voltage level allocation scheme keeps the coding device complexity manageable
3Speed
If the arbitration field is reduced to increase data rate, then the transmission speed improves, but the prioritizing and non-destructive arbitration characteristics are lost
Solution Approach 1:
Multiple arbitration bits are merged into fewer transmitted bits during the arbitration field, reducing the time required for arbitration while preserving the prioritizing and non-destructive characteristics. The voltage level allocation maintains the ability to determine winner and loser stations without losing the essential arbitration properties
Solution Approach 2:
The patent uses voltage level parameter changes to maintain arbitration functionality with reduced bit transmission. By carefully allocating voltage levels to bit combinations, the system preserves the prioritizing and non-destructive arbitration characteristics while achieving faster data rates
Data Source
AI summary
A subscriber station for a bus system and a method for time-optimized data transmission in a bus system are provided. The subscriber station comprises a coding device for coding and/or decoding bits of a message to/from at least one further subscriber station of the bus system, in which at least temporarily an exclusive, collision-free access of a subscriber station to a bus line of the bus system is ensured, wherein the coding device is designed to allocate, during the coding of the message, to at least two bits as bit combination, a predetermined voltage level for a bit time and/or wherein the coding device is designed to allocate, during the decoding of the message, at least two bits as bit combination to a predetermined voltage level for a bit time.