DCCWiki, a community DCC encyclopedia.

Short Definition

Additional features on a decoder, such as lighting circuits.

Functions are additional circuits/outputs on a decoder that can control nearly anything you can think of - lights, sounds, smoke, animation, uncoupling devices, etc. Many are not limited to simple on/off functions - for example lighting functions are capable of imitating Mars Lights, Gyralites, Rule 17 dimming, single or double flashing strobes, ditch lights, and other effects. Output is generally 12 volts DC - if you want to use LEDs or low-voltage lights, you'll need to use a resistor as well.

There are currently 29 functions, F0-F18. Many DCC systems now support 29 functions, while some may still only support 13, F0-12.

The NMRA DCC standard doesn't define functions, but allows for features such as this.