With DCC, there are many ways to modify (program) the way your loco runs and works. You can program the loco to start with the first click of the throttle knob, slow the top throttle speed down, match loco speeds between two dissimilar locos, even program in your own custom speed curve to provide whatever kind of control you want. In addition to all that you can program lights to work the way you want, with all kinds of special lighting effects such as Mars light, Gyralites, Blinking Ditch Lights, strobes, and many more. If that isn't enough, you can even have sound which can be programmed to match your wants and desires. This is all accomplished through programming.

The word programming is intimidating for some people. They think they'll never get this stuff because they know they don't know how to program a computer. In fact, many people with DCC put off learning about programming and doing it because that word is so intimidating. Decoder programming is not like computer programming at all, and really isn't even programming. It's more akin to data entry than anything else.

Configuration Variables are the memory locations where the decoder looks to see what you want it to do. When programming a decoder, all you're doing is entering various numeric values into these memory locations. The values you enter are outlined in the documentation you get for the decoder. If the manual says you enter a value of 22 into memory location CV51 to create a Mars light simulation, that's all you do - tell the system to put 22 into CV51.

The first thing to know is that all Configuration Variables (CVs) are set with a default that your locomotive will run with - no programming necessary. The only requirement for any programming is to be able to have multiple locomotives running independently on the same layout at the same time - you must program a different address into each decoder. The default address that comes in most decoders is address "03". The loco will run on that address. But if you have two locos, both with address "03", they will both run at the same time when you command address "03" to go.

So, let's program a different address into the decoder. Let's say that the road number on the side of the loco is 2025. To keep things easy to remember, a good rule is to use the last two digits of the loco number as the address. That way, all you have to do is look at the road number to know what the address of the decoder is.

To start with, you put the loco on the programming track. With a Digitrax DT400 throttle (different throttles and systems have different procedures - different, but just as easy), you first press the "PROG" button. If the display doesn't already show "AD2" on the left, then turn the left knob counter clockwise until it does. When the display shows "AD2" in the left side of the display, you then dial in the address you want with the right knob. Since we decided we want address "25", use the right knob to dial in "25" on the right side of the display. Most of the time you would have to turn the dial clockwise to get there. But if the display shows an address greater than 25, you would turn the knob counter-clockwise to get down to "25". Once the display shows "AD2" in the left and "25" in the right, press the "ENTER" button. With that, the system does the programming and will respond with "Good" in the display if everything went properly. At this point, you can do more programming by dialing the CV in with the left knob and the value in with the right knob. When you're done with all the programming, press the "EXIT" button and you're ready to select the loco with address 25 to run.

Reading the procedure above makes it sound like more than it is. So here's the recap below, without the long drawn out explanations:

1) Put the loco on the programming track
2) Press the "PROG" button
3) Dial in AD2 with the left knob
4) Dial in "25" with the right knob
5) Press "ENTER"
6) Press "EXIT"

There are other alternatives with the DT400, such as keying in CVs and values in instead of dialing them in with the knobs. Not all throttles have the option of programming either way.

Programing almost everything else is just as easy, and there is generally more than one way to do almost everything. For example, if you want to use the full four-digit loco road number as the address, you can. Just be sure your system, throttle, and decoders are capable of four-digit addresses. Because it uses four digits instead of two, the procedure is a little different, and it uses two different CVs. Again, all this is covered in the programming manuals of your system and decoders.

These are the basics. However, as stated before, there is generally more than one way to do things with DCC. Additional programming topics include:

Service-Mode Programming
OPS-Mode Programming
Read/Write Programming
Configuration Variables
CV Bit Manipulation

Basic programming is something you will need to learn how to do - at least to program in the address you want for each loco. How much more you need to learn about programming depends on how many of the special features you want to use and modify.