A Guide TO Dcc Page 12 A Guide to DCC

12 Consisting Sometimes for steam fans but more often for diesels, there is little more thrilling than seeing a brace of high powered locomotives pulling together on a train. Many model railroaders enjoy doing the same thing on their layouts. When multiple diesel units that can be easily broken up are tied together they are called multiple units MU. When done on a model railroad via DCC, its called Consisting, and allows one set of commands to control and operate multiple locomotives at the same time. Without consisting, the locomotives would have to be run like the old steam locos, with a crew operating each loco. There are three types of consisting in DCC: Basic Universal Advanced Basic Consisting is the simplest. Basic consisting is performed by simply programming the same address to the locomotives that are to be MUed together. No special DCC capabilities are required, and it is conceptually very simple. Same address same response. Of course, there is no way to break up the consist, other than to reprogram the address of each loco. However the advantage is that it is very reliable, and can easily be applied to locomotives that are always run together. The principle disadvantage with basic consisting is there are multiple locomotives assigned to one address. As such, any CV (Configuration Variables) changes made to that address will be picked up by all locomotives with that address. It makes it very hard to make any CV changes on the ly by using programming on the main. Universal Consisting has the DCC command station handle the MUing of the locomotives. Basically the command station issues specific commands to each of the unique addresses of each loco in the consist. The command station must be programmed for the consists in use, and it tracks and issues the commands as needed to keep the MUed locos running together. Typically, the command station uses one of the locos as the lead loco and operators use that address to control that loco and all the following locos in the consist. The principle advantage of this method is that any decoder can be MUed with any other. Principle disadvantages are that it requires the command station to keep up with issuing commands to each loco in the MU. Strictly speaking, there is a slight delay between the responses of each loco, but it generally is short and not noticeable. The other issue with universal consisting is if the command station forgets an MU setup, or for that matter, all of them. If that happens, it is a time consuming effort to re-enter the MU information, especially if it is a larger layout. Finally, if the locos are brought to another layout, they will not run as an MU set. Without the DCC command station, they dont know that they are supposed to be MUed, and will run independently. Advanced Consisting uses the features found in most modern decoders. In essence, each decoder has memory for two DCC addresses: its primary address and its consist address. CV19 selects whether the loco uses the primary or the consist address. When programming an advanced consist all the handling of CVs and addresses is generally done in the background. But what this means is the locos are truly MUed together when in an advanced consist. Even when taken off the layout and brought to another layout, they will remember their MU address and run together. Additionally, since all the locos are responding to a single MU address, they Modelers and prototype railroads love to mix and match power. With several DCC systems different loco styles made by different manufacturers can be programmed to operate with matched speeds and acceleration rates. Prototype photo by Bob Gallegos.

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