Command Station

== History ==
In the early days of DCC, the command station was a separate entity. Two components were required: a command station and a booster. Today, most systems integrate a booster within the command station's enclosure.All DCC layouts necessitate both a command station and a booster. The role is to amplify DCC packets from the command station. Larger layouts may have multiple boosters to power various devices, but only a single command station, as there can be only one command station per layout. The throttle network connects between the command station, which provides digital packets, and the booster, whose output is connected to the track. In the mid-1990s, a small company called RamFixx Technologies introduced their revolutionary RamTraxx DCC system, which integrated the command station and booster into a single unit. Combining both units into a single package reduced RamTraxx’s cost by approximately 20%, compared to the separate command stations and boosters commonly used at the time. Many refer to the integrated device as the command station. 
When powering up the command station, it’s crucial to take precautions to prevent the booster portion from unexpectedly energizing the layout. Additional boosters should be powered up after the command station to avoid this issue. Older command stations with ‘’’program outputs’’’ can be repurposed to a dedicated program track.
=== Summary of System Components ===
 A layout can have only one command station, although it may have multiple boosters. 
If another command station is detected on the throttle network, this creates a conflict, which many command stations avoid by shutting down. Often an issue with modular layouts. Some integrated command station/boosters can be configured to operate in booster only mode. Should the configuration change to activate the command station the resulting conflicts can be difficult to troubleshoot. In this situation check for the presence of another command station first.
A standalone command station requires a booster to function, such as those by Lenz. An integrated unit has both the command station and booster in the same package.
Another type incorporates not only the command station and booster, but includes the throttle within the same unit, such as the Digitrax Zephyr system. CVP's EasyDCC command station has the throttle and command station in the same package, but requires an external booster such as their ZoneMaster. Many entry level DCC systems use this approach.
== Purpose of the Command Station ==
The command station controls the throttle network, accepting commands from throttles and other devices, processing them, sending the resulting instructions to the booster or other devicesThink of a component audio system, where the CD player needs an amplifier to drive the speakers.. The booster amplifies the digital data stream from the command station to the required voltage. The booster's output is a completely digital signal which is applied to the track, or layout accessories. On the track are locomotives, with their multifunction decoders. Other accessory decoders, controlling turnout motors and crossing gates, may also be connected to the track or the throttle network to receive commands. 
The command station can be the limiting factor of a DCC system. It is responsible for keeping track of which trains are controlled by various throttles. They are also responsible for a host of other items, such as interpreting additional functions sent by the throttle or creating Universal Consists.
For example, if a command station supports short (Primary) addresses only, multifunction decoders will only see primary"Two digits" in Hexadecimal, valid values are from 1 to 127. addresses on the track, even though the decoder is capable of understanding an Extended AddressThese addresses range from 128 to over 10,000.. (The actual range of addresses available is determined by the software in the command station). Some budget oriented DCC Starter Sets may limit the total available addresses to 10. The same applies to features like speed steps, consisting, programming methods and the maximum number of locomotives which can be controlled by the command station.Any limitations imposed by the command station must be identified on the package and in the manual, as per the NMRA DCC Standard. 
 Limitations of the command station must be identified on the packaging so the buyer can make an informed decision. 
Command stations vary from manufacturer to manufacturer, offering different levels of features. Differences may include the amount of memory allocated (or slots in a Digitrax system) for running trains, range of functions supported, upgrade or expansion possibilities, output current (expressed in amperes) available to the track and the total number of throttles supported. Make sure you understand what you are getting, so you will not be disappointed or overwhelmed with capabilities. Keep in mind you do not have to use all the features of a command station to get a basic layout up and running. It's easier to not use functions and features than it is to add these later on – adding features usually requires a new command station.In some cases the command station's firmware can be updated, in other cases newer throttles offer additional features. Some throttles may also permit their firmware to be upgraded.
Of course, prices vary based on the features of the command station. Be sure to do your research on various brands and models before making a selection. Some command stations will limit the features available, whereas others are only limited by the features of the throttle connected to it.
Note that in most cases, Command Stations offered by various vendors are incompatible with other brands.
=== Data Rates ===
The command station is able to transmit between 150 and 200 packets per second to the decoders. You might be asking "Is that a lot?" Let's put this into human terms:
Example: Ten decoder-equipped locomotives on the track. Each decoder will receive data packet addressed to it 15 to 20 times each second. This is important because in the absence of a packet bearing its address, a loco will continue doing what it was doing...indefinitely. If a packet of information is corrupted for some reason, it simply takes roughly a tenth of a second longer for the locomotive to respond to the change. Most people will be unable to tell that an error took place in such a short amount of time.
The software in the command station can optimize transmission rates, by prioritizing packets. This minimizes lag when a large number of locomotives need to be handled in a timely manner. Addresses with no change in status are transmitted less frequently so that addresses with changing data can be handled quickly. For example, a mainline freight with the highball compared to a shunting engine, one has little changes to the throttle, the other has many.
=== Throttle Networks ===
The command station is the center of the throttle network. This network connects both throttles and boosters, as well as other accessories, to the command station. There are different types of throttle networks, depending on the manufacturer. This means that one brand of DCC equipment will not be compatible with another, due to differences in the throttle network. 
;The type of throttle network has no impact on the interoperability of decoders on the track. The NMRA DCC standards apply to the DCC signals on the track only, and do not include throttle networks. 
Category:DCC
Category:Command Station