Ethernet Interface Hardware Logic for Jitter-Free Cyclical Telegram Transmission
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Solution Overview
Problem
Ethernet message transmission in real-time applications experiences significant jitter due to fluctuating interrupt latencies, routine code fluctuations, and bus allocation delays, potentially exceeding maximum permissible jitter values, requiring complex compensation methods like IEEE 1588 for accurate time synchronization.
Innovation Solution
A method for continuous transmission of Ethernet messages using an interface that converts data according to Ethernet protocol standards, ensuring jitter-free sending by determining the optimal cycle time and message length, and synchronizing real-time applications with the transmission operation, while preventing collisions and message overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ethernet messages are sent cyclically using standard software drivers and Ethernet controllers, then data transmission can be achieved, but significant jitter occurs due to fluctuating interrupt latencies, routine code fluctuations, and bus allocation delays
Solution Approach 1:
The patent extracts the time-critical transmission function from the standard Ethernet controller software driver chain and implements it in dedicated hardware logic within the Ethernet interface. This separates the jitter-prone software processing from the time-critical message generation, eliminating interrupt latency and routine code fluctuations from the transmission timing path.
Solution Approach 2:
The patent replaces the software-based message generation mechanism with a hardware-based state machine that automatically generates Ethernet messages according to a predefined cycle time. This substitution eliminates the variability introduced by software execution, including interrupt handling and bus allocation, providing deterministic timing.
2Manufacturing precision
If complex compensation methods like IEEE 1588 are used to achieve accurate time synchronization, then jitter can be compensated, but device complexity increases significantly
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing the optimal cycle time and message parameters in the hardware interface before operation. The state machine is pre-configured with the exact timing parameters needed to generate messages at precise intervals, eliminating the need for runtime synchronization calculations and complex compensation algorithms.
3Loss of time
If the cycle time is shortened to improve real-time response, then responsiveness increases, but the risk of message overflow and transmission errors increases
Solution Approach 1:
The patent changes the parameters of the Ethernet messages (length, segmentation) and the cycle time to find the optimal combination that ensures complete transmission within the shortened cycle. The hardware interface monitors the transmission status and adjusts the messaging parameters to prevent overflow while maintaining the short cycle time for real-time responsiveness.
Data Source
AI summary
When data are sent in the form of Ethernet messages on an Ethernet transmission link using an interface to link a node to the Ethernet transmission link, the data to be sent are converted using a conversion unit in line with a transmission standard of the Ethernet protocol in order to provide Ethernet messages, and a transmission unit is used for ongoing transmission of the provided Ethernet messages, with Ethernet messages being output onto the Ethernet transmission link continuously.