What is Digital Command Control (DCC) For Model Trains?

The hobby of building and maintaining model train sets and whole model railway networks, like almost every other hobby people get invested in, can be quite simple or really complex depending on how much someone wishes to expand their projects. Model train networks can be as simple as a singular circular loop passing through a tunnel and beside some handmade landscapes, to as complex as multiple model train stations managing a fleet of 30 trains passing through a number of towns and always successfully avoiding a collision.

That kind of model train network however, would require an almost impossible level of careful planning and track layout structuring without the help of a tool known as the DCC. The DCC, its full name being the Digital Command Control, does exactly what said full name implies; digitally and automatically manages a multitude of trains so that they run along various routes and through various stops without colliding and with as minimal user input as possible.

When Did the Digital Command Control Come About?

The first ever record of a Digital Command Control system for model train sets is set in the 1980’s, when it was designed by Lenz Elektronik GmbH of Germany for Märklin and Arnold (both German manufacturers of model trains and tracks) under a contract. The first ever commercial units weren’t available to the public until as late as 1989, when they were first introduced for Arnold. Märklin got its units the following year of 1990. However, soon after the release of these first ever DCC units, both Märklin and Arnold exited the agreement citing patent issues. Lenz Elektronik however, continued to hone its design.

Within a couple of years following the agreement breakup, the National Model Railroad Association’s Command Control committee had requested submissions from model train set manufacturers for the organization’s proposed command control standard. Märklin and Keller Engineering heeded the requests, and that led to the NMRA Command Control committee approving the Märklin and Lenz command control system.

Though having approved of the Märklin and Lenz design at first, the NMRA Command Control committee decided to devise its own protocol for command control systems instead. However, this protocol was also heavily based on the Märklin and Lenz design, and the committee had also decided to make it a digital system. It was then named the Digital Command Control system, and was first debuted according to the NMRA Command Control committee’s standard in 1993. An upgrade to the system, developed by Lenz, Kühn, Zimo, and Tams in 2006 and standardized in 2007, allows the Digital Command Control Unit to interface with the trains to know which section of which track that train currently occupies.

Should a Beginner Bother With a DCC?

If you’re relatively new to the world of model trains, you might not know if you should bother getting a Digital Command Control system for your model railway network. The answer to whether you should depends on what kind of railway network you’re looking to, or already have, set up.

If the model railway network you’re working on is a simply track with one train that goes around it, you definitely do not need to get a DCC system. If you are running two or three trains simultaneously, it depends on how large your track is and how many track switches and other mechanical features you include. Any more trains than that and you definitely need to invest in a DCC system. And that’s where the first problem comes in; cost.

DCC systems come in all kinds of build and functional qualities and their respective pricing, but even the cheapest ones can start to get a bit heavy on your pocket if you’re running a lot of trains. This is because for each train you run, you’re going to need a DCC decoder unit that plugs into the locomotive unit of that train. These DCC decoders are used to allow communication between the track and the train that is currently on the track, and a large number of trains means having to buy a lot of DCC decoders.

Another problem accompanying the purchase and use of DCC systems is the installation of those decoder units in the trains. For beginners and newcomers to the model train community, this can be a difficult step. Newer locomotive units meant for more complex model railway networks usually include an easy plug and play socket that accepts any standardized DCC decoder. Some of the fancier and slightly more expensive options even have DCC decoders already installed inside them. But if the locomotive units you own do not have DCC decoders or at least their required sockets, you will have to install them yourself. And that might be almost impossible if you’re completely new and clueless, and people ask for some pretty expensive costs for installing the DCC decoders for you.

How Do Digital Command Control Systems Actually Work? 

We’ve talked about when the DCC system was first introduced, and we’ve also covered the basic questions you need to answer before deciding on buying a DCC system, so now let’s actually understand how Digital Command Control systems actually work. The overall working of a DCC system is quite simple, if the underlying technical workings and mechanics are ignored in favor of a more layman level understanding of the whole system.

In the simplest of explanations, a DCC system works with power supplies, command stations, boosters, and the aforementioned DCC decoder units installed within the locomotives running along the tracks. The DCC command stations are the brains of the whole operation, and send out and receive electrical signals along the tracks of the whole railway network. Boosters (also called amplifiers in some cases) may be used (with assistance from their power supplies) to help the DCC command stations modulate the voltage and encode digital messages inside the voltage along the tracks while also providing electrical power to the model trains.

The DCC decoders installed within the locomotives then receive these messages via the electrified tracks and decode them to understand the instructions written within. These instructions are then passed over to the motor of the locomotive, which the DCC decoder then takes direct control of and subjects to the whims of the DCC command stations. With the newer standardizations introduced in 2007, the trains can also let the DCC command stations know if they’ve accepted the commands, and where they currently are relative to the whole railway network.

DCC command stations can pass on a variety of instructions to the trains running along the tracks depending on the currently required circumstances. Usually, these instructions are used to slow or speed up a certain train to avoid collisions, maintain a train’s speed over uneven terrain, and emulate realistic slowing down and speeding up of the model trains. Also, compared to analog control of a model network, DCC systems make it incredibly easy to manage multiple trains along switching tracks because they eliminate the need to install separate switches along the tracks to manage passing trains.


This is all of course a basic understanding of the whole DCC system. How it all works is quite fascinating if you’re into figuring out the workings of automated machines and systems. Furthermore, though the complexity of installing DCC decoders in trains and their relative costs are two major factors to affect your purchase of a DCC system, there are a few other things you should be on the lookout for as well. Mainly, be sure to actually test out whichever DCC system catches your fancy, be it at your local hobby store or a model railroad club. You don’t want to end up with a system you don’t like using, especially after laying down so much cash.