Synchronized FA Network Control With Conditional Resend Requests
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Solution Overview
Problem
Existing communication systems in factory automation (FA) networks, such as those described in PTL 1, require multiple transmissions of frames to ensure delivery, leading to excessive bandwidth consumption and inefficient communication.
Innovation Solution
A control system with synchronized apparatuses that transmit resend requests only when frames fail to arrive at defined times and under specific cycle conditions, ensuring efficient and reliable communication by limiting bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transmission frames are sent successively without waiting for response, then communication reliability is improved, but network bandwidth consumption increases
Solution Approach 1:
The patent implements a feedback mechanism where receiving apparatuses send response frames to the transmitting apparatus. The transmitting apparatus waits for these responses before determining whether to retransmit frames. This feedback loop enables reliable communication while avoiding unnecessary retransmissions, thus reducing network bandwidth consumption compared to sending multiple frames without waiting for responses.
2Reliability
If resend requests are transmitted whenever frames do not arrive, then communication reliability is improved, but network bandwidth consumption increases
Solution Approach 1:
The patent dynamically adjusts the resend request transmission behavior based on the control cycle timing. The transmitting apparatus calculates whether there is sufficient time remaining in the current control cycle to complete a resend operation and still meet the next cycle's deadline. This dynamic adjustment ensures reliable communication when time permits while avoiding unnecessary bandwidth consumption when the cycle is too tight.
Solution Approach 2:
The patent changes the parameter of resend request transmission from a static always-on approach to a conditional approach based on cycle timing parameters. By evaluating the relationship between the current time, frame arrival time, and control cycle duration, the system adapts its resend behavior to optimize both reliability and bandwidth usage under different timing conditions.
Data Source
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AI summary
A control system, an apparatus, and a method that allow efficient communication are provided. A plurality of apparatuses in time synchronization with one another are connected to a network. The network transfers a frame periodically exchanged by the plurality of apparatuses. The plurality of apparatuses include at least one control device and an apparatus controlled by the control device. Each of the plurality of apparatuses is connected over the network, to a first apparatus that transmits a frame that arrives at each of the plurality of apparatuses and a second apparatus that receives a frame transmitted from each of the plurality of apparatuses. When a frame does not arrive at defined time through a transfer path and when a condition associated with a cycle is satisfied, at least one of the plurality of apparatuses transmits a resend request through the transfer path.