Switching Router Realtime Cycle Scheduling
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Solution Overview
Problem
Ethernet-based automation systems face challenges in ensuring calculable and load-insensitive response times due to their 'best effort' principle, which is load-dependent, leading to unpredictable cycle times during high communication traffic.
Innovation Solution
A method dividing the transmission cycle into phases where only real-time data is sent initially, followed by a phase for both real-time and non-real-time data, and then suppressing non-real-time data transmission, utilizing priorities to ensure real-time data can be sent with determinable cycle times, and implementing time synchronization between switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the 'best effort' principle is used for data transmission, then good response times are ensured under normal conditions, but response time becomes load-dependent and unpredictable during high communication traffic
Solution Approach 1:
The patent implements periodic transmission cycles divided into different phases (realtime phase and non-realtime phase). During the realtime phase, only realtime data telegrams are transmitted with guaranteed cycle times, while during the non-realtime phase, non-realtime data telegrams are transmitted. This periodic structure ensures that realtime data transmission is not affected by load from non-realtime traffic, resolving the contradiction between response time guarantee and load independence.
2Reliability
If scheduling is implemented to ensure calculable cycle times for realtime data, then response time predictability improves, but network capacity utilization decreases due to reserved cycle times
Solution Approach 1:
The patent segments the transmission cycle into distinct phases: a realtime phase for deterministic realtime data transmission and a non-realtime phase for best-effort non-realtime data transmission. This segmentation allows the network to guarantee calculable cycle times for realtime data while still utilizing the network capacity for non-realtime traffic during its designated phase, thus resolving the contradiction between cycle time calculability and network capacity utilization.
3Productivity
If non-realtime data telegrams are transmitted during the realtime phase, then network capacity is efficiently utilized, but realtime data transmission experiences delays and loss of determinism
Solution Approach 1:
The patent uses periodic transmission cycles with clearly defined phases. During the realtime phase, only realtime data telegrams are transmitted, ensuring deterministic behavior and transmission guarantees. During the non-realtime phase, non-realtime data telegrams are transmitted to utilize network capacity. This periodic separation prevents non-realtime traffic from interfering with realtime traffic, resolving the contradiction between network capacity utilization and realtime transmission guarantee.
Data Source
AI summary
A method and a switching router for simple scheduling of realtime data telegrams with calculable load-insensitive cycle times. A transmission cycle (4) is subdivided into three phases. In a first phase (1), only realtime data telegrams are sent; in a second phase (2), realtime and non-realtime data telegrams are sent; and in a third phase (3), the transmission of long non-realtime data telegrams is suppressed. Short filler telegrams can be sent during the phase (3). This ensures that data transmission of the realtime data telegrams will proceed smoothly. Transmission in certain phases is regulated by the priorities assigned to the data telegrams.