Digital Command Control (DCC)
Digital Command Control, commonly known by the acronym "DCC," refers to the Digital Command Control Standard created by the National Model Railroad Association (NMRA).
DCC revolutionized train control by allowing for multiple locomotives to operate independently on a layout.
DCC control is accomplished in two ways on a layout. First, the layout must be wired with a DCC system. This typically includes a wiring bus below the track that sends power and DCC signals (packets) from the command station to the rails. Second, locomotives must be fitted with a DCC decoder. This is, in essence, a computer chip that is capable of "decoding" DCC commands sent along the rails to each locomotive.
Decoders
The DCC standard ensures that any locomotive with a DCC decoder, regardless of manufacture, will work with any DCC system. All TCS decoders conform to the DCC standard and can be used with all commercially-available DCC systems.