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In short, decoders can be addressed by either 2 digits, or 4 digits. If you have many decoders, you will want a system that can handle 4 digit addressing. If you are running, or using, a smaller layoout, 2 digits will give enough unique addresses for all your decoders.

[edit] Select-and-Run

With DCC there is no need to worry about where the train is located, which throttle you're using, or toggle any switches get a throttle to talk to a loco. To run a loco, you simply pick up a throttle, select the loco address (number) you wish to run, and run it. This allows you to easily, and quickly, allow you to control the trains speed, direction, lights, sounds, or any electronic devices such as decouplers or animation.

NMRA defines two ranges of addresses:

• The first is 0 through 127. This is called the "Primary" address. It is a one Byte address which in Hexadecimal (see Binary) can have the digits 00₁₆ to 7F₁₆ (0 ..127 decimal) - hence is called a two digit address. Other terms used for the Primary address are "Short address", "Base address", "7-bit address", and "2-digit address".

• The second range of addresses is from 0 through 10239 (0000₁₆ to 27FF₁₆ - hence 4-digit address). This is called the "Extended" address. Other terms used for the Extended address are "4-digit address", "14-bit address" and "Long address". (Note that this is a 14-bit binary number. To reach FFFF₁₆ (or 65535₁₀) 16-bits or two Bytes would be needed).

All DCC Command Stations, Throttles, and Decoders support two-digit (Primary) addressing as per the NMRA standard. Even if your equipment has four-digit addressing, you don't have to use it.

Notice: There is some overlap of addresses, different command stations handle that overlap differently.

[edit] Digitrax

• 0 analog
• 1-127 primary address
• 128-9983 extendend address

[edit] EasyDCC and Lenz

• 0 analog
• 1-99 primary address
• 100-9999 extended address

[edit] NCE

• 0 no loco selected
• 1-127 can be either primary or extendeded depending on how selected, a leading 0 will make selection extended.
• 128-9999 extended address

Current NCE does not support analog, older NCE did using a home built analog only throttle.

[edit] Which one should I use?

If you have less than about 20 or 25 locos on the layout, two-digit addressing usually works the best. Just give each loco the address of the last two digits of the road number on the side of the loco and you are good to go. If you have duplicate numbers that way, see if it works out better by using the first two digits of the road number. If that doesn't work out, you may have to renumber one or more locos - or use four-digit addressing. Remember, no matter if you picked the first two, or the last two number, just be consistant.

To use four-digit addressing, you must have a command station, and decoders that support four-digit addressing, and throttles that can use it. Typically, all decoders support four-digit addressing, and the majority of DCC systems support four-digit addressing. You'll need to research your system for compatibility.

[edit] External links

[Hexadecimal]