Distribution Node Switching Table for Real-Time Data
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Solution Overview
Problem
Current distribution nodes in automation networks face challenges in reliably transmitting real-time and non-real-time data packets, leading to potential overload situations and buffer overflow due to uncontrolled forwarding of non-real-time packets, which can delay real-time packets and disrupt cyclic processing.
Innovation Solution
A distribution node with at least two input/output interfaces and a switching device that uses a switching table to manage data packets, where real-time packets are forwarded at predefined times and non-real-time packets are transmitted during transmission pauses, with the switching device determining the transmission duration and checking for available pause times to ensure non-real-time packets are forwarded without delaying real-time packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-real-time data packets are forwarded without control, then the transmission of non-real-time packets is simplified, but overload situations occur and real-time packets are delayed
Solution Approach 1:
The distribution node dynamically adjusts its forwarding behavior based on the type of data packet received. For real-time packets, it uses predefined transmission times from the routing list; for non-real-time packets, it checks buffer availability and transmission pause durations. This dynamic adaptation allows the system to maintain simplicity while ensuring real-time reliability.
Solution Approach 2:
The system implements feedback mechanisms by monitoring buffer occupancy and transmission pause durations. Before forwarding non-real-time packets, the distribution node checks whether the transmission buffer has sufficient capacity and whether the current transmission pause duration is adequate. This feedback control prevents overload situations and ensures real-time packet priorities are maintained.
2Reliability
If non-real-time data packets are transmitted during transmission pauses, then buffer overflow is prevented, but the transmission duration of non-real-time packets increases
Solution Approach 1:
The distribution node performs preliminary checks before forwarding non-real-time packets. It first determines the transmission duration required for the non-real-time packet, then checks whether the transmission buffer has sufficient capacity and whether the current transmission pause duration is adequate. This preliminary action prevents buffer overflow while minimizing delays by only forwarding packets when conditions are favorable.
3Reliability
If transmission pause duration is checked for each non-real-time packet, then real-time processing integrity is maintained, but the device complexity increases
Solution Approach 1:
The distribution node applies different processing qualities to different data packet types. For real-time packets, it uses simple predefined transmission times from the routing list without additional checks. For non-real-time packets, it implements the transmission pause duration check. This local quality differentiation maintains real-time processing integrity while minimizing the increase in device complexity by applying complex checks only where necessary.
Data Source
AI summary
A distribution node for an automation network comprises at least two input/output interfaces for transmitting and receiving real-time-relevant and non-real-time-relevant data packets, and a switching device connected to the input/output interfaces. The switching device forwards data packets received via an input/output interface via a further input/output interface using a switching table, where the switching table contains at least a data packet identifier and a transmission time in a data transfer cycle for each real-time-relevant data packet. Inter alia, the switching device can detect a data packet identifier on reception of a real-time-relevant data packet, and output the real-time-relevant data packet at the transmission time allocated to the detected data packet identifier in the switching table via an input/output interface as a transmission interface.