Taming the Spaghetti: Why Bus Inports & Outports Deserve Your Respect

Have you ever opened a Simulink model and been greeted by an endless forest of Bus Selector blocks, with wires weaving across the canvas like a plate of spaghetti?

The Hidden Problem

Chances are that all the signals in your model might come from a single bus. Every-time you require a signal into your subsystem, you will need a bus selector, which will result in a mess of wires. This will also make the model difficult to maintain in the event where there is any change in the signal order in the bus.

Model With Bus-Selectors

The selected bus signals

The Shift: From Spaghetti to Structure

Here’s where Bus Inports and Bus Outports shine:

• Instead of unpacking and repacking signals at every boundary, you just define the interface once.

• The subsystem doesn’t care how many signals are inside the bus—new ones slide in without rewiring.

• You eliminate the infinite Bus Selector/Cable Factory at the edges.

It’s like switching from manual lines to having a clean API for your model.

Why It Works in Practice

When you replace spaghetti wiring with clean bus interfaces:

• The top-level model stays readable (just one input, one output).

• Subsystems evolve gracefully—signals can grow, shrink, or reorganize.

• Debugging is easier—you probe the bus, not the tangled web.

• Code generation maps directly to structs—clear, maintainable C code.

And most importantly: You stop wasting hours on rewiring every time requirements change.

Model with Bus inports, which results in a cleaner layout

The bus signals are selected inside the subsytems with Bus element ports.

The Takeaway

The next time you see a model drowning in Bus Selectors, pause and ask:“Do I really need all these selectors here? Or should this be a Bus Inport/Outport interface instead?”

Nine times out of ten, the cleaner, more scalable answer is the latter.