Kallaroonian Posted February 24, 2012 Share Posted February 24, 2012 I'm just starting out with DCC and thinking about buying the system and a couple of decoders to experiment with. What does it mean when a decoder has "n" functions? Does this relate to the numbers of outputs it can control Eg 1 for motor, 1 for lights, 1 for sound = 3 function decoder or does it mean something else? thks Link to post Share on other sites More sharing options...
smokebox Posted February 24, 2012 Share Posted February 24, 2012 Motor control is not counted as a function. A 2 function decoder can usually control front (1st function) and rear lights (2nd function) which willl be directional and switched on and off by funtion control 0 (zero) on the controller. Some decoders can, I think, reassign these functionns to behave differently. Further functions are not directional and many of the better decoders allow these functions to be re-mapped to different function controls on the controller. Link to post Share on other sites More sharing options...
Adrian Wintle Posted February 24, 2012 Share Posted February 24, 2012 As smokebox says, motor control is not counted as a function, nor is sound. A function is a separately controllable output. It is mildly confusing because the term function is also used for the control input from the DCC control station. As mentioned above, most decoders are set up (by default) to use [control input] function 0 to control [decoder] function 1 and 2 giving head and tail lights. You need a function for every separately controllable light (or other device like a smoke generator) on the loco. Most higher end decoders give you a lot of programmability for their functions, allowing you to modify the control input that activates tham as well as the effects (flashing, flicker, etc.) they produce. Adrian Link to post Share on other sites More sharing options...
Crosland Posted February 24, 2012 Share Posted February 24, 2012 [pedant] Functions are internal to the decoder. Electrical connections are made via the outputs wires. Directional lighting is two functions FL(f) and FL®. In reality it is function o qualified by the direction of the loco. The two connections for forward and reverse use two outputs. The functions can be mapped to different outputs within the decoder. Theoretically the same function can be mapped to multiple outputs. [/pedant] Andrew Link to post Share on other sites More sharing options...
RMweb Gold Oldddudders Posted February 24, 2012 RMweb Gold Share Posted February 24, 2012 What does it mean when a decoder has "n" functions? Does this relate to the numbers of outputs it can control Eg 1 for motor, 1 for lights, 1 for sound = 3 function decoder or does it mean something else? Just adding to the advice already offered - your function needs will vary considerably according to the era you model. If you are modern era, with lots of lights and other operable features on your diesel or electric loco/mu, then multiple functions will help you get the most out of DCC in your locomotives. If you are a UK steam era modeller, then there isn't much for the functions to control, at least in the smaller scales, unless you use a smoke generator, as mentioned above. Link to post Share on other sites More sharing options...
Adrian Wintle Posted February 24, 2012 Share Posted February 24, 2012 [pedant] Functions are internal to the decoder. Electrical connections are made via the outputs wires. Directional lighting is two functions FL(f) and FL®. In reality it is function o qualified by the direction of the loco. The two connections for forward and reverse use two outputs. The functions can be mapped to different outputs within the decoder. Theoretically the same function can be mapped to multiple outputs. [/pedant] Andrew Hence my differentiation between control input function and decoder function. The decoder function is a hardware driver tied to a specific output wire/pad and is the thing that is counted when a decoder is defined as an x-function decoder. This means that it has the physical hardware and connections to support x independent functions. This answers the OP's question. The control input function is a factor of the firmware of the decoder and how it responds to function commands from the control station. This is the piece that, depending on the decoder, can be reconfigured/remapped. This is not what the OP is asking about. Depending on the DCC manufacturer FL(f) may actually be called F0f. Adrian Link to post Share on other sites More sharing options...
Ron Ron Ron Posted February 24, 2012 Share Posted February 24, 2012 What does it mean when a decoder has "n" functions? Does this relate to the numbers of outputs it can control As explained above, the number of functions specified, excludes motor drive related functionality. The "functions" are accessory outputs, that can drive a variety of different items, such as... lights smoke generators DCC operated couplings roof fans servo motors ..or any other thing within reason. The number of functions (e.g. 4 function decoder etc) determines the number of such outputs. Fully featured decoders normally come with 4, 5 or 6 function outputs. Some high end ones have more. Budget and lower price decoders normally come with 3 or 4 functions, with smaller ones designed for N gauge or small 00/H0 sometimes only having 2. Some high end decoders have extra, higher power rated function outputs for particular applications, in addition to their normal function outputs. Sound functions are contained within the decoder and don't have outputs associated with them. . Link to post Share on other sites More sharing options...
Kallaroonian Posted February 26, 2012 Author Share Posted February 26, 2012 Thanks for the info everybody. I intend to try a recent A3 and an old Airfix 31 as my first experimental DCC locos. I'm not sure I can see a need for more than 2 functions ! While we're on the subject of unecessarily confusing technical options what is the deal with the number of connection pins (8, 21 ?) thks Link to post Share on other sites More sharing options...
RMweb Gold mcowgill Posted February 26, 2012 RMweb Gold Share Posted February 26, 2012 21 pin supports more connections between the circuit board on the loco and the decoder, allowing more functions to be used. Bachmann have moved towards general use of 21 pin boards as I guess it helps reduce the number of different components needed even through steam locos will not make use of the additional capability. At the other extreme 6 pin decoders tend to be smaller and used in N gauge or small 00 locos such as the Bachmann class 03. You will find many 8-pin decoders have an extra wire from the decoder that is not connected to the piug, that's to support additional functions beyond those the 8-pin layout can support. I guess that's not generally very user friendly so more pins on the connection solves that problem, but adds more confusion for newcomers. Martin Link to post Share on other sites More sharing options...
Ron Ron Ron Posted February 26, 2012 Share Posted February 26, 2012 Decoders have traditionally come with either plain wires for soldering into a loco, or with a connector fitted to enable easy fitment into suitably equipped model locos. The connector is located either on the decoder PCB itself, or on the end of a wiring harness. In the past the number of pins on those connectors has either been 6 or 8 (there was an earlier 4 pin connector for large scale), or 9 in the case of the JST connector on some American decoders. The 6 and 8 pin connectors are a standard European MOROP approved type, adopted by the US NMRA and are as such, a de-facto universal standard.. With the demand for an increase in the number of accessory functions provided on decoders, it became clear that 8 or 9 pins was not enough. For example, 8 pin connectors can only support 3 functions via the pins and so any 8 pin decoders with 4 functions or more, require the use of additional wires to be able to use those extra functions. As those extra wires have to be soldered in, it begins to negate the purpose of using a connector in the first place. The 21 pin MTC connector was introduced as a temporary measure to solve this problem, until agreement could be reached on a new multi-pin connector. Therein lies the confusion, as there are 6, 8, 9 & the temporary 21 pin options (not forgetting the virtually defunct 4 pin) and non of these are compatible with each other, unless via adapter plugs or harnesses. To help solve that problem, the new NMRA and MOROP NEM658 standard multi-pin connector, is designed to be a universal solution, enabling various sizes of decoder, with different numbers of pins, to be totally compatible with each other. The new standard connector is the PluX system, which comes in 8, 12, 16 & 22 pin sizes - one pin is actually an unused blank indexing position to prevent installing decoders the wrong way round. These new connectors are now being included on new European RTR models and there are a range of matching decoders available from most of the major European DCC decoder manufacturers. Although it's early days, expect to see a more widespread use of the PluX connectors in the coming years as the older types of connector are slowly withdrawn from inclusion on new models. (note: the NMRA recommend that RTR manufacturers should stop fitting 21 pin connectors on new models. This was effective as of January 2010 onwards, i.e. 2 years ago.) . Link to post Share on other sites More sharing options...
Kallaroonian Posted February 27, 2012 Author Share Posted February 27, 2012 Folks, thanks for the info Link to post Share on other sites More sharing options...
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