Topologies

Overview

On this page:
Scale Up | Scale Out

Abstract: Here is my vision of the RTB architecture for modular layouts.

Dive into the heart of your model railway and discover a new way to build. This isn’t about traditional wiring and fixed layouts—it’s about freedom, flexibility, and a future where your railway can grow as fast as your imagination. The Real-time Bus (RTB) system introduces a revolutionary architecture with “scale up” and “scale out” topologies, allowing you to seamlessly expand from a small home setup to a massive exhibition without ever rewiring a thing.

Explore how a single RTB domain can handle any size layout, from a simple loop to a sprawling metropolis, and see how multiple domains can effortlessly merge to create a single, unified railway system. This is my vision of building a modular, future-proof layout that is limited only by the common object server’s resources.

Scale Up

Scaling up (vertically) means scaling resources within a single RTB domain. This domain provides a single namespace for all rolling stock as well as accessory modules distributed across the layout. A single RTB domain is the standard and covers most use cases from small to large.

Maximum specs of a single RTB domain,

  • up to 16 power domains
  • up to 16 DCC generators + boosters
  • up to 896 track sensors (Railcom + Current)
  • up to 4096 accessory modules

Small topology

An entry level setup may look like this: Three layout modules hooked together which could be a fiddle yard setup.
  • 1 PC
  • 1 USB connection
  • 1 powerboard /w DCC booster
  • 3 (4x) = 12 feedback tracks
  • 1 accessory
The setup represents a single Power Domain and a single RTB Domain.
RTB (Real-time Bus) entry level topology

Medium topology

A possible scale up expansion of the setup above may introduce an additional powerboard. In general each powerboard represents a RTB Power Domain. Now we have 7 layout modules, our fiddle yard from above attached to a main station made up by 4 segments.

  • 1 PC
  • 1 USB connection
  • 2 powerboards /w DCC boosters
  • 8 (4x) = 32 feedback tracks
  • 7 accessories

The new setup represents two Power Domains but still is a single RTB Domain.

RTB (Real-time Bus) expanded entry level topology

Continuing the scale up we grow the setup by another 4 segments (e.g. marshalling yard) also using its own powerboard.

  • 1 PC
  • 1 USB connection
  • 3 powerboards /w DCC boosters
  • 13 (4x) = 52 feedback track
  • 13 accessories

The setup now has been expanded to three Power Domains but remains a single RTB Domain.

RTB (Real-time Bus) topology with three Power Domains

Large topology

Scaling up further to a reasonable sized home layout,
  • 1 PC
  • 1 USB connection
  • 6 powerboards /w DCC boosters
  • 23 (4x) = 92 feedback track
  • 24 accessories
The setup has now grown to six Power Domains but remaining to be a single RTB Domain.
RTB (Real-time Bus) topology with many Power Domains

Scale out

Scaling out (horizontal) means scaling resources by adding additional RTB Domains. The PCs merge the horizontal layout topology on the IP network layer.

To grow beyond the boundaries of a single RTB Domain multiple RTB domains may joined together (scale out). In this example, the setup from above (lets call it RTB Domain A) has been joined by RTB Domain B and C. Please note, each RTB Domain may be located in different rooms and still be joined via the IP network.

Use Case: Three hobbyist groups meet for an exhibition and combine their layouts.
  • Group A adds layout “RTB Domain A”
  • Group B adds layout “RTB Domain B”
  • Group C adds layout “RTB Domain C”
Merging the environment is fully automatic and non-destructive to any of the configs, i.e. no change of configuration required. There is no limit on scale out other than the resources (CPU, RAM, Network bandwidth) on the common Object Server.