Aircraft Daisy-Chain Network Position-Based Delay Configuration
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Solution Overview
Problem
Daisy-chain network configurations in aircraft and spacecraft face delays due to processing and forwarding times, which complicate setup and reconfiguration, especially when adding or removing nodes, and require careful consideration to avoid collisions.
Innovation Solution
The network employs a master device and slave devices connected in series with each slave device having an identifier and an adjustable time delay element, allowing for flexible ordering and reduced delays by setting delay periods based on relative position, eliminating the need for reassigning identifiers and increasing upstream bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If slave devices are connected in daisy-chain arrangement with identifiers assigned in order along the chain, then the network setup is simple, but delays accumulate along the chain and reconfiguration requires reassigning identifiers
Solution Approach 1:
The system pre-calculates and stores optimal delay periods for each possible position in the daisy-chain before runtime. When a slave device is installed, it simply reads its position and applies the corresponding pre-determined delay period, avoiding the need for complex real-time calculations or identifier reassignment during reconfiguration.
2Speed
If slave devices transmit response messages immediately after receiving polling messages, then response time is minimized, but collisions occur between responses from different slave devices
Solution Approach 1:
Each slave device is configured with a position-specific delay period that is locally optimized for its location in the daisy-chain. Devices closer to the master use shorter delays, while devices farther away use longer delays, creating a graduated delay structure that prevents collisions while maintaining overall system responsiveness.
Solution Approach 2:
The system changes the time delay parameter based on the slave device's position in the daisy-chain. By dynamically adjusting the delay period according to position, the system optimizes both response speed and collision avoidance, allowing immediate responses from nearby devices while preventing overlaps from distant devices.
3Loss of time
If star topology is used to reduce delays, then polling delays are minimized, but wiring complexity and weight increase
Solution Approach 1:
The system changes the temporal parameter (delay period) to compensate for the spatial arrangement in the daisy-chain topology. By adjusting timing parameters rather than physical layout, the system achieves star-topology-like performance without the associated wiring complexity and weight.
Data Source
AI summary
A network for an aircraft including a master device and slave devices connected in daisy-chain arrangement series. Each slave device has a unique identifier. The master transmits polling data packets along the slave devices, each including only one identifier. Polling data packets are transmitted in successive sequences, each including for each slave device only one polling data packet and including the polling data packets in a predetermined order. Each slave device includes a first data interface for connection in an upstream direction, a second data interface for connection in the downstream direction, and a processing unit to compare for each received polling data packet the identifier thereof with the identifier of the respective slave device, and output a response data packet to the master device if the two identifiers match, and forward the polling data packet to the second interface at least if the two identifiers do not match.