Wired Node-to-Node Planning Guide

Table of contents

1. Wired Node-to-Node Planning Guide
   1. Overview
      1. Configuring Wired Node-to-Node Communication
      2. Frequently Asked Question
      3. Benefits of Wired CAN in LCC Fusion

Overview

In the LCC Fusion Project, reliable wired communication between nodes is achieved using the CAN bus standard. CAN (Controller Area Network) provides robust, differential signaling that is ideal for noisy environments and long cable runs.

Unlike wireless ESP-NOW, CAN requires a shared electrical bus with proper wiring and termination. The Node Bus Hub and Node Cards simplify this setup by automatically managing CAN connectivity and termination.

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Configuring Wired Node-to-Node Communication

1. Identify the Bus Ends

   • CAN requires a linear bus with two ends.
   • Termination resistors (120 Ω across CAN_H and CAN_L) must only be present at the two endpoints.

   In the LCC Fusion Project:

   • The Node Card, Quad-Node Card, and Node Bus Hub all include automatic termination circuits.
   • Termination is engaged only when the device is physically at the end of the bus.
   • No jumpers, switches, or manual configuration are required.

   When sharing the CAN bus with other LCC devices (non-Fusion):

   • External devices generally do not provide automatic termination.
   • If such a device is at the end of the bus, its termination must be enabled manually or added with an external resistor.
   • Across the entire network—Fusion and non-Fusion combined—there must always be exactly two terminations, one at each end of the bus.

2. Select Cabling

   • Within the LCC Fusion Project, the CAN bus is carried using standard network cables (CAT5 or CAT6).
   • These cables provide twisted pairs, which are ideal for differential signaling (CAN_H and CAN_L).
   • Using network cables ensures consistency, easy availability, and compatibility with Node Cards and Node Bus Hubs.

3. Chain Hubs if Needed

   • Multiple LCC Fusion Project Node Bus Hubs (PCB boards) can be interconnected to expand the system.
   • Each hub provides both multiple 8-pin headers (for direct board-to-board connections) and a pair of RJ45 sockets (for remote connections using standard CAT5/6 network cables).
   • This flexibility allows hubs to be chained together locally or over longer distances while maintaining proper signal integrity on the CAN backbone.
   • Automatic termination still ensures that only the physical endpoints of the combined chain are terminated.

   flowchart LR; 
   nonFusionNode["Non-LCC Fusion<br>Node/Device<br>(CAN Bus Termination)"]
   can(("CAN Bus Network"));
   hub[["LCC Fusion<br>Node Bus Hub"]];
   hub2[["LCC Fusion<br>Node Bus Hub"]];
   n1[["LCC Fusion<br>Node Card<br>(CAN Bus Auto-termination)"]];
   n2[["LCC Fusion<br>Node Card<br>(CAN Bus Auto-termination)"]];
   pc[["LCC Fusion<br>Power-CAN Card"]];
   iocards[["LCC Fusion<br>I/O Cards"]];
   iocards2[["LCC Fusion<br>I/O Cards"]];
   bb1[["LCC Fusion<br>Breakout Boards"]];
   bb2[["LCC Fusion<br>Breakout Boards"]];
      
   subgraph layout ["Train Layout"];
   direction LR;
   nonFusionNode --> can;
   can --> n1;
   can --> pc;
   subgraph clsuter ["LCC Fusion<br>Node Cluster"]
   n1 <--> |"CAN"|hub;
   pc --> hub;
   hub <--> |"CAN"|hub2;
   hub --> |"Network Cable, or <br/> Direct Connection"| hub2;
   hub --> iocards;
   hub2 --> iocards2;
   n2 <--> |"CAN"|hub2;
   end;
   iocards <--> bb1 <--> devices((Devices));
   iocards2 <--> bb2 <--> devices2((Devices));
   end;
      
   classDef lSalmonStyle fill:#FFA07A,stroke:#333,stroke-width:2px,font-size:24px;
   class hub,hub2 lSalmonStyle;
   classDef lightGrayStyle fill:#d3d3d3,stroke:#333,stroke-width:2px,font-size:24px;
   class layout lightGrayStyle; 
   

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Frequently Asked Question

Can I use a network hub to interconnect CAN Bus Networks or Node Bus Hubs?

• No. A traditional Ethernet network hub or switch cannot be used with CAN.
• CAN is not packet-based like Ethernet; it is a differential electrical bus.
• Only CAN-compliant hubs or backplane wiring may interconnect Node Bus Hubs.

Why can LCC Fusion connect multiple Node Bus Hubs?

1. Short branches The hub only fans out into short stub connections to the Node Cards and other boards. Since CAN bus performance degrades if you have long stubs (“star” wiring), keeping these branches very short maintains the proper daisy-chain topology.

2. Auto termination Each Node Card includes an auto-termination circuit. This ensures that when a card is the last device in the chain, a 120 Ω termination is applied automatically across CAN-H and CAN-L. This prevents reflections and guarantees that you always have correct termination at both ends of the bus — without needing manual jumper settings.

   Together, the short stubs + auto termination give you a CAN/LCC bus that behaves like a proper terminated daisy-chain, which is why your Node Bus Hub “just works” in practice.

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Benefits of Wired CAN in LCC Fusion

• Reliable – CAN is robust against electrical noise and long distances.
• Modular – Node Bus Hubs allow plug-and-play expansion.
• Error-Proof – Automatic termination prevents configuration mistakes.
• Scalable – Multiple hubs and nodes can be chained together as one continuous bus.