Centralized control is a fundamental concept of DCC, in that the Command Station knows what locos are running at any one time, therefore an effective way to stop all locos by going through the "list" of ones running is easy.
Greg,
Got to take issue with you on this one?
The emergency stop command is a broadcast command under DCC, which all decoders should respond to. - So the Central Station (in effect) 'shouts' stop-all, and all the decoders should respond to this.
(I do not know of a manufacturers system, which sends 'stop', to each address it thinks is running, in turn?)
The Central Station knows which loco's you have sent commands too, but can not know which are actually running, as DCC is a broadcast transmission system, with no feedback, to acknowledge receipt of a command, or (under normal running) way of knowing if a command has been implemented.
Hence DCC sends each command a number of times, and hopes it has been received.
This is different on a programming track, where the decoder acknowledges receiving (and acting) on a command by the 'twitch' we see of the motor. - The CS detects this, but it does not transmit any 'data' (in a '0' or '1' sense) back to the CS.
Simplified explanation, I know, but think the whole audience should get this?
