Token Circulation Management for Ethernet Buffer Overflow
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Solution Overview
Problem
In Factory Automation (FA) networks using Ethernet, the star topology often experiences data delays and frame losses due to buffer overflow in switching hubs, especially when a large number of slave stations transmit data simultaneously, compromising real-time performance.
Innovation Solution
A communication management apparatus that manages data transmission in Ethernet networks by using a token circulation mechanism to minimize the number of times a token frame passes through transmission lines, determining the token circulation order based on network presence information, and ensuring efficient data frame transmission and reception without collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of slave stations are connected to the control system in a star topology, then the network capacity and connectivity are improved, but the buffer memory of the switching hub becomes exhausted causing data delay and frame loss
Solution Approach 1:
The patent applies preliminary action by having slave stations transmit data to the master station before the buffer memory becomes exhausted. The switching hub proactively manages data flow by transmitting accumulated data to the master station in order, preventing buffer overflow and ensuring real-time performance is maintained even with many connected slave stations.
2Stability of the object's composition
If data from multiple slave stations is accumulated in the buffer memory of the switching hub, then all data can be transmitted to the master station in order, but the data transmission time exceeds the predetermined time limit
Solution Approach 1:
The system performs preliminary action by accumulating data in a controlled manner in the buffer memory before transmission, ensuring proper ordering is established in advance. This allows the switching hub to transmit data efficiently to the master station without exceeding the predetermined time limit, as the ordering process is completed during the accumulation phase rather than during transmission.
Data Source
AI summary
The communication management apparatus includes a network-presence-check processing unit that performs network presence check processing for generating network presence information, a token-circulation-order determining unit that determines token circulation order using the network presence information, a setup processing unit that notifies each of communication nodes in the network of token circulation destination information, a token-frame processing unit that, after transmission of a data frame by a data-frame-communication processing unit, transmits, based on the token circulation order, a token frame including information concerning a transmission right acquiring apparatus that acquires a transmission right next and determines whether the transmission right acquiring apparatus of the transmission right acquiring apparatus information of the received token frame is the own apparatus, and the data-frame-communication processing unit that performs transmission and reception processing for a data frame for acquiring the transmission right.