Table of contents
  1. Why LCC Fusion Uses Specialized I/O Cards
    1. Why All-in-One Boards Create Hidden Costs
      1. 1. You rarely use all of the functionality
      2. 2. They cost more to build or purchase
      3. 3. You still need more boards as the layout grows
      4. A Better Question Leads to a Better Design
    2. Fusion’s Design Principle: One Job Per Card
    3. Specialized Cards Make Wiring Obvious
    4. Specialized Cards Reduce Configuration Overhead
    5. Reliability Improves When Behavior Is Fixed
    6. Expansion Becomes Predictable and Affordable
    7. Specialized I/O Cards Work Hand-in-Hand With Breakout Boards
    8. Troubleshooting Is Faster and More Localized
    9. Open-Source Friendly by Design
    10. Why This Matters

Why LCC Fusion Uses Specialized I/O Cards

How focused, single-purpose cards reduce cost, simplify wiring, and make expansion predictable.

Before explaining why Fusion uses specialized I/O cards, it’s worth addressing a common assumption in layout automation:

Wouldn’t a single all-in-one I/O board be simpler?

In practice, all-in-one boards often work against you.

Why All-in-One Boards Create Hidden Costs

Universal I/O boards are designed to handle many different tasks at once. While that sounds convenient, it usually leads to three predictable problems.

1. You rarely use all of the functionality

All-in-one boards must support many device types and use cases. On a real layout, most users only need a subset of that capability.

The result is:

  • unused connectors
  • unused features
  • unused circuitry

You pay for complexity you never use.

2. They cost more to build or purchase

Supporting multiple voltages, signal types, and operating modes requires:

  • additional components
  • extra protection circuitry
  • configuration logic
  • more testing and documentation

Even if you need only one function, you still pay the full cost of the board.

3. You still need more boards as the layout grows

Layouts expand. Blocks, signals, and turnouts multiply.

Eventually, even an all-in-one board reaches its limits. At that point, users add another all-in-one board—again carrying unused features—rather than adding only what is actually needed.

A Better Question Leads to a Better Design

If expansion is inevitable, and if unused features are common, then a more practical question emerges:

Why not start with multiple smaller boards that do exactly what you need, cost less per unit, and can be added incrementally as the layout grows?

That question is at the core of Fusion’s I/O card strategy.

Fusion’s Design Principle: One Job Per Card

LCC Fusion deliberately avoids universal I/O boards. Instead, it uses specialized I/O cards, each designed to perform one specific function—and nothing more.

Examples include:

  • block occupancy detection
  • turnout motor control
  • signal lamp outputs
  • digital inputs
  • PWM outputs
  • sensor interfaces

Each card has a clear purpose, a predictable behavior, and a simple electrical design.

Specialized Cards Make Wiring Obvious

When an I/O card has a single responsibility:

  • connectors are clearly labeled
  • pin usage is unambiguous
  • documentation is shorter and more focused
  • wiring mistakes are far less likely

A turnout card looks like a turnout card. A signal card looks like a signal card.

Users never have to ask, “Which mode is this pin in?”

Specialized Cards Reduce Configuration Overhead

All-in-one boards often rely on:

  • jumpers
  • DIP switches
  • software modes
  • mixed-use pins

Fusion avoids this entirely.

Specialized I/O cards:

  • have fixed electrical behavior
  • expose only the signals they need
  • rely on the Node Card for configuration and logic

This reduces decision-making and eliminates common setup errors.

Reliability Improves When Behavior Is Fixed

A single-purpose design allows:

  • simpler circuitry
  • tailored protection
  • fewer edge cases
  • more thorough testing

If something fails, the cause is easier to isolate because each card’s role is well defined.

Expansion Becomes Predictable and Affordable

As layouts grow, new capabilities are added by:

  1. installing another specialized I/O card
  2. plugging it into the Fusion Node Bus Hub
  3. connecting a breakout board
  4. wiring the device

No existing cards need to be reconfigured. No unused features are carried forward.

Cost and complexity scale with actual needs, not hypothetical ones.

Specialized I/O Cards Work Hand-in-Hand With Breakout Boards

Fusion intentionally pairs:

  • I/O Cards for function
  • Breakout Boards for device-specific wiring

This allows the same I/O card to support many real-world devices simply by changing the breakout board—without redesigning or replacing the I/O card itself.

Troubleshooting Is Faster and More Localized

When a problem occurs:

  • the affected function points to a specific card type
  • wiring issues are isolated to a breakout board
  • diagnostics are faster and clearer

This is especially important for club and modular layouts maintained by multiple people.

Open-Source Friendly by Design

Because each I/O card has a clearly defined role, others can design:

  • new card types
  • alternate implementations
  • specialized variants

All without impacting existing designs or documentation.

Why This Matters

Specialized I/O cards are not a limitation—they are what make Fusion practical.

They ensure that:

  • every board installed is useful
  • costs stay proportional to needs
  • expansion remains incremental
  • wiring stays understandable
  • complexity never outruns the layout

Fusion doesn’t try to do everything on one board. It does exactly what’s needed—no more, no less.

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Last updated on: December 17, 2025 © 2025 Pat Fleming