Functions

A function is one decoder feature — lights, horn, coupling, a sound effect, and so on — shown as a named button with icons instead of a bare F number. Function maps and trains pick functions from a shared library.

Most of the time you only need the built-in library when building a function map. Use this page when nothing fits — even after searching for a generic icon — and you want to create your own.

What is a function? Each function has two pictures: one for off and one for on, so in Control you can see at a glance whether it is active.

Functions also have a behaviour type:

Latching — tap once to turn on, tap again to turn off. The feature stays in that state until you change it. Lights are usually latching: you turn them on for a while and leave them.
Momentary — the feature is only on while you hold the button; release and it stops. Horns and many sound effects are momentary — you would not want them stuck on after a tap.
Automatic (default) — If you are not sure what to choose, or have a function that does not fit into the other categories, choose automatic. How the function works will then depend on how you press the button: a short tap will latch the function on, while a long press will activate a momentary effect. This is how most DCC controllers work. This also supports more complex patterns that some manufacturers use.

Lights — latching (off / on)

Horn — momentary (off / on)

Step 1: Add New Function

Open functions on the Panels DCC website

Screenshot: Functions library — add new function

Step 2: Name and behaviour

Give the function a short, clear Name — the label you will see in Control and in the map picker.

Choose a behaviour type:

Latching — for features that stay on until you turn them off (lights, sound engines, and similar).
Momentary — for features that should only fire while you hold the button (horns, whistles, many effects).
Automatic — the default when you are unsure; short tap latches, long press is momentary.

Step 3: Off and on icons

Supply a picture for the off state and one for the on state. Keep them simple and high-contrast so they stay readable on a throttle at arm’s length.

Match the style of the built-in icons where you can — that way your custom function sits comfortably beside library ones on the same train.

Screenshot: New function — name, type, and off/on icons

Step 4: Save

Save the function. It then appears in the picker when you edit a function map or a train, so you can drop it onto any F number like any other library entry.