Each DCC decoder that is installed in a locomotive is assigned a unique address.
To select a locomotive and run it on either throttle, you must know the address assigned to the decoder. Digitrax decoders are set up at the factory with the “default” digital address of 03. This means that when you take a Digitrax decoder out of the package and install it in your loco, you can select address 03 on your throttle and run the decoder. The first Configuration Variable (CV) programmed by most DCC users is the decoder’s address since it is not very useful to have all of your locos run on address “03” and responding to the same instructions. If you do not know the address of the DCC locomotive you want to run, you can simply program the decoder’s address and select it to run using its newly programmed address.
With Digitrax DCS100 & DCS50 command stations, and others, it is possible to read back the decoder’s address.
Selection of a locomotive address is done in Lo (Loco) mode, which is the default mode for the DT300. It is the default mode because it is the mode that runs your trains. If you change to Sw (Switch) or Mu (Multi Unit) mode and there is no activity on the throttle, the DT300 will automatically return to Lo (Loco) mode after a few seconds.