HVAC controller area network hybrid network topology
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Solution Overview
Problem
Existing HVAC CAN network systems require manual electrical termination of nodes, leading to decreased signal quality and increased installation time due to variability in termination settings, especially when adding new devices.
Innovation Solution
A CAN network topology with predetermined termination impedance at three primary nodes, allowing for plug-and-play installation of additional devices without altering termination resistors, ensuring consistent signal quality and data throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual electrical termination of nodes is implemented in CAN network, then signal reflection can be controlled, but installation time increases and installation variability increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring termination resistors at fixed locations (primary nodes) during system design and manufacturing, rather than requiring field installation personnel to manually configure termination at each node. This preliminary setup eliminates the need for manual termination adjustments during installation, reducing both installation time and installation variability while maintaining signal quality.
2Reliability
If manual termination settings are required at each node, then signal integrity can be optimized, but device complexity increases
Solution Approach 1:
The patent extracts the termination configuration task from individual nodes and consolidates it at primary nodes only. By removing the requirement for manual termination settings at end nodes and intermediate nodes, the system reduces device complexity and simplifies installation while maintaining signal integrity through the predetermined termination network architecture.
3Reliability
If termination resistors are changed when adding devices, then signal quality can be maintained, but adaptability decreases
Solution Approach 1:
The patent applies universality by designing a standardized termination architecture where predetermined termination resistors at primary nodes serve all end nodes and intermediate nodes uniformly. This universal termination approach allows any number of devices to be added to the network without requiring changes to termination resistor values, enhancing network expandability while maintaining consistent signal quality across the entire network.
Data Source
AI summary
The present disclosure provides a CAN network topology for an HVAC communication system. The CAN network topology comprises at least three primary nodes having a predetermined termination impedance and a plurality of end nodes coupled to each primary node, wherein the predetermined termination impedance is set to the optimal setting of 180 ohms. Advantageously, the present disclosure eliminates the need for physically setting CAN node terminations. This reduces install time and removes variability of the install settings. Further, removing this variability reduces the risk for post-installation call-backs due to incorrect system setup. The present disclosure optimizes signal slew rate, which improves signal reliability.