What is Command Control?
Using modern electronics, it is possible to use the rails of a model railroad to carry both power AND information at the same time. Using modern digital technology (Ones and Zeroes, as in computers) a LOT of information can be sent over the rails in a short period of time. Again using digital technology, small units to pick out (recieve) and act upon particular messages can be made affordably.
All together, systems which send power and messages over the rails to recievers in locomotives or other trackside locations are known as carrier control or command control systems.
Various individuals and companies have experimented with these ideas to produce and/or sell command control systems for model trains. However, none of the early developments really worked together; there was no "common language" for the information messages travelling on the rail.
The National Model Railroad Assn. recently adopted a standard for putting power and information on the rail, providing the "common language" which has been missing. This is called the Digital Command Control (DCC) Standard.
The standard will allow different manufacturers to now produce command control components which can work well together. Company A's transmitter will correctly control company B,C, and D's recievers in different locomotives.
In practice, one person's or several people's commands (speed, direction, turnout position, etc.) are electronically combined, and put on the rails all over the railroad.Recievers act only upon the messages sent to them, using track power to do their jobs. This allows much greater flexibility in the operation of model locomotives, as two or more locomotives can be right next to each other, yet be controlled by different people, OR, combined together under the control of one person.
With command control, layout wiring can be greatly simplified, since the need for blocks is greatly reduced or eliminated.
