Power Conversion

DCCWiki, a community DCC encyclopedia.

Short Definition

Ability of a DCC decoder to operate on a non-DCC layout


Known as Alternate Power Source in the NMRA DCC Standard.

Many mobile decoders can operate on non-DCC or non-standard DCC layouts. The most commonly supported power conversion type is Analog Conversion where a DCC-equipped locomotive can operate on a traditional analog layout.

Many users set their decoders to NMRA Digital Only. This prevents the locomotive from running on a Direct Current layout, unless changed. The purpose for setting it to only operate on NMRA DCC is to prevent runaways. If the decoder loses the digital signal for a defined period of time, it will switch to the Alternate Power Source as defined in CV 12

List of Power Conversion Types Available in CV 12

The NMRA standard recognizes the following power conversion types (although none of them are required to be supported by an NMRA compliant decoder).

This is not a fixed list, as the NMRA will consider requests from manufacturers to add additional power conversion modes.


These the the assigned codes for Power Source Conversion that are found in CV 12.

These are presented in decimal form.

1 = Analog Power Conversion

2 = Radio

4 = Zero 1

8 = Trix

16 = CTC 16 / Railcommand

32 = FMZ

These values come into effect when CV 1 is set to all zeros.
Warning - Using a Primary Address (CV 1) of "0" will enable this feature and overrides any value in CV29. A combination of a Primary Address of 0 and CV12=1 will result in an immediate runaway when DCC power is connected to the rails.