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When I took on the assignment of being the DCC Corner columnist for Model Railroader magazine I decided it was time to start a website where I could post additional information that I just didn’t have room for in the monthly column–so here we are.
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- 2 digit addressing or 4 digit addressing
Normal direction of travel
Speed step control: 28/128 or 14 speed steps
Analog mode conversion on or off
Speed table on or off
So, let’s take a look at each. Two- vs four-digit addressing is pretty straightforward. While you can enter both a two- and four-digit address into the appropriate CVs this setting determines which your decoder will respond to. Most folks prefer using the locomotive number in the four-digt address but it can be useful to have a two-digit address available. For example you might want to run your locomotive 2238 at the club but find someone else is using that address already. By simply changing CV29 you could still operate that locomotive using address 38 instead.
The normal direction of travel setting determines which end of the locomotive is considered front and therefore which way the locomotive will go in relation to your throttle setting. However, be aware that if you install the motor leads backwards then simply changing this may not be a quick fix since it will also affect the directionality of your headlights.
Speed step control is important in that you don’t want to be operating on 14 speed steps. This is one of those legacy features from the early days of DCC. There still may be a few old command stations that only support 14 speed steps but in most cases this is one of those features you will likely never use.
The analog mode setting is very important, especially since in new decoders this is the default setting. This determines whether a decoder will automatically respond to DC power on the track. Some folks may have analog mode turned on if they still have a DC layout at home or the club and want to be able to run with either DC or DCC. However for most folks I recommend this feature be turned off. When intermittent shorts occur on the tracks, they can create a DC pulse which confuses the decoder in locos and they can take off at full speed. However if this feature is turned off the decoders will ignore these DC pulses.
The speed table setting determines whether user loadable or three step speed tables are used. Since in most situations the three step speed curves are adequate for speed matching locomotives this is the option of choice. You would only activate the user loadable 28 step speed curves if you desire to dramatically alter throttle response of the locomotive. The easiest way to create one of those is with DecoderPro. Most decoders now take the 28 speed steps and interpolate them to 128 speed steps so you don’t lose anything by using them.
OK, with that background let me say that actually determining a value for CV29 is a complex process, requiring counting bits for each of the five features and summing them into one value to enter into CV29. Digitrax has a free Digitrax Toolbox app for Apple and Android devices and they also have an online CV calculator on their website. To make this real easy I have included a table from the Digitrax literature. Just pick the features you desire and look up the value for CV29 in the first column–I commonly use a value of 34.
CVs 1, 2, 3, 4, 5, 6, and 29 are the basic CVs that most folks might want to program using a throttle. Once you get above these you really are better off using DecoderPro or LokProgrammer. This is also true for CV29 but I will show you what it does anyway in the second part of this post.
CV 1 is the two digit address. It is pretty straightforward, just enter the address and hit enter and you’re done. However with the near universal availability of four digit addresses most folks don’t use this very much anymore. It can come in handy for industrial switcher locomotives and the occasional one or two digit oddball–for example I have an RS11 no. 11.
CV 2 is the initial voltage adjuster. It helps get the locomotive moving as soon as you open the throttle to speed step 1 by adjusti g the voltage to the motor. It also serves as the first setting in a three step speed curve used in speed matching–more on that in a bit. For this one just keep nudging the value up until the locomotive just begins to crawl when you open the throttle a crack. Note though that some decoders also have other CV settings that give an extra nudge at low speed settings to help overcome stiction, so check your manuals.
CVs 3 & 4 are the acceleration and deceleration momentum settings, respectively. These settings slow down acceleration and deceleration rates to help simulate the tendency of prototype locomotives to accelerate and decelerate slowly due to their heavy weight and the weight of the load they are pulling. Some decoders factor this into their other operations so you need to factor that into any changes you make. For example on LokSound decoders the deceleration rate affects how much brake sound you will hear.
CVs 5 & 6 are the top and midpoint speed settings, respectively, for a three step speed curve–CV2 is the minimum speed step setting. To speed match locomotives you set the top and bottom settings and finally adjust the midpoint setting to get two locomotives to operate at the same speeds across the throttle range. See my previous post and video on speed matching for more on this process.
CV29 is often called the master CV since it controls several features. Calculating a value for CV29 is complex enough that some programming throttles and command stations do it for you based on your input. Digitrax has a table of common values in their decoder manual making it easier to understand this CV. Because of its complexity I will cover it later.
On my layout I have a couple frogs at the beginning and end of a gantlet track over the Rockfish River bridge. Often when I run a locomotive through one of the frogs the PSX circuit breaker will trip. This is not consistent, only when a locomotive has passed in the opposite direction. So what is going on? Well first, I have the frogs protected with Frog Juicers. These Frog Juicers are a great option for controlling the polarity of turnout frogs in a situation like this one where a switch machine is not used. These small electronic circuits sense when a locomotive’s wheels contact a turnout frog and the polarity doesn’t match. In this situation the circuit automatically corrects the frog polarity before the booster short circuit detection kicks in.
But why did I get a short only after a locomotive passed in the opposite direction. Well that locomotive tripped the Frog Juicer resetting the polarity. So when the next train came from the opposite direction the polarity was incorrect, tripping the PSX and resetting the polarity. This flip-flop went on until I found out that the PSX was tripping before the Frog Juicer could do its thing–why? Actually, the Frog Juicers are (electronically) very slow. The default trip time on the PSX is about 3ms making it faster than the Frog Juicer, so it will trip first. So how do you fix this? On the PSX set CV55=1 and CV65=128, and the PSX delay will be slower and should work with the Frog Juicers.
I’ve frequently commented on ops mode programming and I use it almost all the time no matter whether I am using a throttle or DecoderPro to program decoders. Ops mode programming was introduced on Wangrow System One command stations about 1995 to allow operators to change features like momentum and other features on the fly. I remember the late Don Wangrow telling me how he wanted his System One customers to be able to back a locomotive up to a train, couple up, increase the momentum using ops mode, and proceed with the feeling that it is pulling a really heavy load. Many new decoders now have this change in momentum built in to a function button setting.
Times have changed and now one of the big advantages of ops mode programming is that because it is done on the main tracks it is able to use the full voltage and current available. This means there are likely to be fewer problems when programming sound decoders and when keep alive circuits are installed. These devices are power sinks because they have large capacitors that must be charged up. On the service mode track, power is only applied when a programming command is being sent. As a result the capacitors may not be fully charged and they siphon current that normally would go to programming. They can also interfere with the read back capability.
This is further complicated by the fact that only 250 mA is available on the service mode track and the voltage may be inadequate. However on the main track since power is always on, the capacitors stay charged and there are fewer problems. This makes ops mode programming more reliable. This is enough of an issue that decoders like LokSound, which program best with 13 volts are more reliably programmed. ESU also recommends removing keep alive circuits when using service mode programming with LokSound decoders and I suspect this would help with other brands as well.
Another advantage of ops mode is the programming commands are only sent to the address of the decoder you are programming, essentially eliminating the chances of programming other locomotives. However, there is one exception to this. If you enter an address of ”00” the commands will go to all decoders, so be careful what address you enter. The other advantage that I really like is the ability to test the effect(s) of changes you make to CV settings. This makes it very easy to test a bunch of different speed curve settings when speed matching or when changing sound volumes.
To get around the problem of not being able to read CV settings I usually work from DecoderPro and therefore can see the value I last programmed into the decoder. As long as I don’t make any changes using just a throttle and always save my changes before closing the locomotive file, I don’t need to be able to read the CVs. If I am using ops mode programming with a throttle such as with speed matching I keep a notepad handy and write down the changes in CV settings as I proceed. When I am satisfied I then enter the final values into the DecoderPro file to keep my information up to date. It may take a few extra steps, but it gets the job done.
There are two ways to program decoders, (1) service mode, and (2) ops mode. In the past I have talked a lot about ops mode programming so let’s focus a little on service mode. With service mode you can program all CVs without regard to the decoder address. Accordingly, all decoders in locomotives on the service mode programming track will be reprogrammed. This was an important feature for many years because with some decoders it was the only way to change the address–you couldn’t do it with ops mode. However because it indiscriminately programs any decoder on the programming track you need to be careful with some DCC systems. Some entry level systems such as the Digitrax DB150 and NCE PowerCab only have a single pair of track connectors that are used for both powering the track and for service mode programming. Because of this it is necessary to have an electrically isolated service mode programming track to prevent programming all your locomotives.
To make this possible you need to have some way to switch your track output from the main track to the service mode programming track. This is easily done using a double pole double throw switch set up with the single pair of wires from the command station connected to the two center switch contacts. Another pair of wires connected to two of the contacts at one end of the switch are run to the track power bus. Finally, a third pair of wires are connected to the two contacts at the other end of the switch and run directly to the programming track. When you want to run trains flip the switch to route power to the main tracks and when you want to use service mode programming switch it so power goes to the isolated programming track.
The problem is remembering to flip the switch—one forgettful moment could result in reprogramming all your locomotives. Because this is enough of a problem for users, NCE now offers a circuit, the Auto-Sw, which senses service mode programming commands and switches power to the programming track for you. This device is not system dependent so you can use it with the Digitrax DB150 or any other entry level system that does not have separate track power and programming outlets.
One useful feature of service mode programming is the ability to read the CV settings in a decoder–you can’t do that with ops mode. (To my knowledge only Lenz has offered a way to read CVs in ops mode and that requires installation of special feedback modules). Using this feature you can check the settings of particular CVs so you are not programming blind. For example it is helpful to know your current momentum settings when making changes just to give you an idea of how much of a change is needed. The same is true for sound levels and speed curves.
One downside to service mode is the current to the programming track is limited to about 250 milliamps. This is done to prevent damage to a newly installed decoder if it is not correctly wired. The downside is that with many sound decoders and when keep alive capacitors are installed, there may not be enough current to program the decoder. This is why Soundtraxx and DCC Specialties introduced the PTB-100 and PowerPax programming track boosters. Ops mode offers a convenient work around for this which I will discuss next time.
It has become obvious from your feedback that a lot of new folks to DCC (and a few old ones) don’t completely understand what their throttles can do, especially when it comes to programming. I’ll talk more about basic programming in a followup post. However, the throttle is probably the most important part of your DCC system since you use it to communicate with the command station and decoders. So if you don’t have a clear understanding of how it works and what it can do you are hamstrung from the get go. First, there are two types of throttles, (1) master or programming throttles, and (2) basic throttles. Basic or utility throttles as simplest so let’s start there.
Basic throttles have a knob or pushbuttons for speed control, a numeric keypad for entering addresses and controlling functions, and in some cases dedicated function buttons. They also have either a pushbutton or toggle for controlling the direction of locomotive travel. They cannot program decoders. Some may have small rotary switches for entering addresses.
Because of their simplicity and smaller number of buttons they are easiest to use and less confusing. Enter a locomotive address, hit the right button and off you go. Because of their limited capabilities you don’t have to worry about a new user accidentally reprogramming a decoder and they are less expensive. They are smaller than the master throttles and often easier to hold and manipulate.
Most DCC systems sets come with a more advanced master or programming throttle. These are much bigger, have a lot more buttons, a digital screen, and with Digitrax, a pair of control knobs for running two trains at once. In most cases to acquire a locomotive you hit a select button, enter the address, and then the enter button and off you go. Most also have a lot of other buttons to deal with. Some may be used for controlling accessory decoders, and some for programming. The important thing is to not push buttons aimlessly just to see what they do! My recommendation is to sit down with your new throttle connected to the command station, open the manual, and follow the quick start instructions. Each throttle is different enough that it is always a good idea to do this.
The various types of keypads either have specific functions identified as F1, F2, etc. or simply numeric 1-0. There may also be specific buttons for horns and lights. In any case you need to know what functions corresponds to which function number. Lights are “0”. The bell is “1”, whistles and horns ar “2”. Function 8 is usually used to turn the sounds on and off. Other than that you have to look up the function number assignments in the decoder manual of info sheet. I have written previously on the inconsistency of function assignments and how to deal with them so do a search for more on that topic.
Programming is different with each master/programming throttle so I am not going to really go there. This is another case where sitting down with the throttle and manual, and going through the steps will be the most productive way to learn the process. Personally I rarely use my throttles for programming anymore. It is so much easier to use DecoderPro. This is especially true with sound decoders and working with anything more than programming an address. About the only time I use the throttle is when I speed match locos since I need to experiment with several different values. So if you got a new DCC system or throttle for Christmas sit down with it and learn what it can do. Finally, keep in mind that no matter how bad you screw up, you can always reset a decoder to factory settings, and turning the power off and back on will clear the command station, so don’t panic and start hitting buttons.
My final tip is about the speed control knobs or pots. Folks love to hold a throttle in the palm of their hand and use their thumb to spin the knob. However you eventually will pay for doing that. The pressure of your thumb against the knob puts pressure on the shaft which is then transmitted into the potentiometer mechanism. This can lead to uneven wear on the internal parts of the potentiometer and in a year or so you will be shipping your throttle back to the factory for repair because it doesn’t work right. This is one of the biggest complaints I hear from folks. To prevent this hold the throttle in the palm of your hand and use the fingers on your free hand to turn the knob—no uneven pressure and your throttle will last a lot longer. This is not a problem with the thumbwheel control on NCE Procabs.
Every once in a while I have to go over some basic material that I have previously covered either in an article or earlier post. At Model Railroader the guiding rule is don’t repeat anything within about three years—after that it’s all fair game. I also tend to get a lot of new folks to the website and they ask questions, sometimes the same ones. This happened with an email I got not long ago from a fellow confused over consisting. Part of his problem was an almost total lack of understanding of how his NCE system worked. What are all these functions they keep talking about was his question to me. To anyone who has any familiarity with DCC this may seem to be pretty basic stuff but consider if you were new to the hobby or at least that aspect of it how would you know how it worked? I guess I could write a very basic introduction to DCC book but given my time constraints that’s not likely to happen, so instead how about a post or two on some important concepts starting with consisting.
Not too long ago I wrote a column on different types of consisting and went over the pros and cons of each, so this will not be that specific. So what is a consist and how do they work? I’m sure you’ve seen multiple locomotives on prototype railroads coupled together and operating essentially as a single unit–this is consisting. It is accomplished by linking them together by connecting their electronic and pneumatic systems. This is done by connecting the hoses that hang down on the front and rear pilots. Consequently, when the engineer in the lead locomotive applies the brakes they are applied in all the locomotives. When he slips the throttle into notch 2, all the locomotives’ diesel engines start to rev up.
So how does this work with DCC? First, remember that we are dealing with what essentially are little computers in our command stations and decoders and they can do some pretty astounding stuff. One way or another, and there are three different types of consists with DCC–basic, universal, and advanced, the DCC system keeps track of them and keeps them doing the same things. These three different methods offer differing levels of control. You link up the decoders in the locomotives so they all respond to the commands issued by one throttle. The devil in the details is how this is done and just what is controlled.
The mechanics of setting up a consist differs among the various throttles. I break throttles down into basic and master throttle classes, with the master throttles having the ability for programming, setting up consists, and having a variety of more advanced features. Some throttles just can’t set up consists at all whereas on others the process can vary from pushing a couple buttons to a semi-automated procedure. Some also include creating advanced consists among their semi-automated procedures. Dig into your DCC system manuals to see what yours can do.
Well we finished out 2017 with 114,904 views, a 19% increase over 2016, so the word seems to be getting out. We’ll see what happens in 2018. Without the book to distract me I plan to do a few more videos and also expand the followup between my DCC Corner columns and posts here. You’ve already seen the columns for January and February, but I’ll give you a hint about March—I feature a poor man’s keep alive, something I came up with 30 years ago when I was using CTC16 command control. After that we’ll take a look at sound decoders including replacing a factory installed sound decoder in a diesel locomotive. There will be other decoder installations plus more on keep alive circuits, programming LokSound decoders and using their LokProgrammer software. Right now I have DCC Corner column topics planned out through the middle of 2019 and the website hosting fee is paid up through 2018 so I’ll probably be at it for another year at least. And if you get bored there are several hundred prior posts covering a range of subjects so feel free to either browse through the archives or do a search for specific topics you may be interested in. As always if you have a question or nagging problem feel free to contact me.
Recently TCS owner John Forsythe showed off their new throttle and command station in a live streamed Facebook video. Right now the new DCC system is under development with release planned for mid to late 2018.
The throttle shown in the photo is only a prototype and the final unit will likely be black. It is ergonomically designed to fit comfortably in your hand and operates for about 20 hours off a pair of AA batteries. You can use either alkaline or rechargeable batteries. The really neat part is the throttle is Withrottle capable which means it can be used with other layouts using the JMRI Withrottle function. You can have a TCS system at home and still use your throttle at the club or other layouts.
It has a 2.3” diagonal screen and will support simultaneous control of two locomotives using the buttons on each side of the thumbwheel. The thumbwheel is offered instead of a traditional knob type speed control. Also all 28+ NMRA functions are supported.
The command station is rated at 4 amps and a higher amperage booster will also be available. Currently the command station has a socket in the rear for an NCE network and connections for other DCC systems are in development. This means you’ll be able to use components from these other systems with the TCS command station. To further increase compatibility the system is LCC compliant which means all other future LCC compliant equipment will be compatible.
I’ll post more information as it becomes available. The release was live streamed on Facebook and I have included the following link to the recorded version. Soome folks iah e rported problems opening the link so you may need to copy and paste it to your browser or simlpy search for the tcsdcc page on Facebook.
My new projects book contains two chapters on building and installing control panels. Because I decided long ago to use Tortoise switch machines on the new Piedmont Southern one chapter deals with them and DC powered control panels. The second chapter goes into using DCC accessory decoders with Tortoises to create pushbutton control panels. I use Tortoises exclusively on the Piedmont Southern—why, well access can be a problem on a double deck layout. Turnouts easily reachable at 48″ elevation can quickly become out of reach at 60″. And the same is true for areas on the lower level hidden underneath an upper deck. So using Caboose ground throws just didn’t seem reasonable and the alternative was motorizing the turnouts, and to control them you need control panels!
For my control panels I lay out the track schematics on the computer and print them out on glossy photo paper. The first two panels, controlling the Charlottesville industrial district and Charlottesville yard are 5″ x 10″ and 5″ x 14″, respectively. Printing them out wasn’t an issue on my Canon photo printer which can handle paper up to 13″ x 19″. The thing you have to remember is to leave enough room between the switches and LEDs–I didn’t in Charlottesville yard and ended up having to redo that panel.
The big pain is then drilling all the holes in the clear acrylic sheet I used to go over the printed schematic for protection. For this I laid the schematic and acrylic sheet out on the box I had built out of plywood and screwed them down through holes drilled in each of the four corners. I then drilled starter dimples in the acrylic sheet directly over each switch and LED symbol on the schematic. Once all the dimples were started I removed the acrylic sheet and drilled completely through each dimple using a 1/4″ diameter bit. For this you need to work slow on a hard flat surface. One small crack and you have to start over again. I used special bits made for drilling acrylic sheet that I found on eBay and they make all the difference!
With all the holes drilled I thoroughly cleaned all the sawdust and plastic bits and pieces off the acrylic sheet and reassembled the control panel–fortunately the holes lined up almost exactly over the switches and LEDs on the schematic. Next using a new #11 blade in my Xacto knife I carefully cut out each switch and LED symbol from the schematic. I then installed SPDT switches in the switch holes and black plastic mounting clips in the LED holes. Now the fun part, installing the LEDs.
In my schematic I placed a green LED on the leg of the switch that will be the normal position and a red LED for the reversed or thrown position. That will serve as a reminder to the train crews to always leave the switch set with the green LED on. To get the polarity correct requires testing the circuit as you wire them. Basically for each switch there needs to be a green and red LED wired together in opposite polarity. Remember that on LEDs the long leg is positive and the short leg negative. Another indicator is that there is a flat spot on the side of the LED next to the negative leg. I just twisted one short and one long leg together then soldered them. To be consistent I placed the long leg on the green LED and the short leg on the red LED next to the switch and the opposite pair of legs away from the switch. Let’s call these the input and output sides, respectively.
Now let’s digress a minute to talk about powering the Tortoises and LEDs. The Tortoise instruction sheet has very good diagrams showing how to use various DC and AC transformers to power these–I went the AC route. I used a 16VAC 1 amp transformer which can power about 50 Tortoise machines–remember a Tortoise only draws about 20 milliamps when stalled. To get the polarized DC current required for the Tortoise requires a couple 1 amp diodes. By simply soldering the pair of diodes to one of the AC transformer wires you get a positive and negative current. The diodes have to be oriented with the white band in opposite positions to get the positive and negative current–the other wire serves as the return leg of the circuit which I’ll call the common. Again, the Tortoise instruction sheet has a very good diagram illustrating this.
Once the power supply is taken care of, you can start wiring the panel. Well, actually I first attached it to the fascia using hinges so it can be flipped up for wiring and maintenance and down for operation. The first step is to wire up a Tortoise as a test unit to use for wiring the LEDs and switches–never power the LEDs without a Tortoise in the circuit or you’ll blow them. Using a jumper with alligator clips I hooked up the common wire to one pole of the Tortoise motor and ran another jumper from the other pole to the output side of the first LED pair.
Next I set the switch on the control panel to point toward the route with the green LED, and soldered the center pole of the switch to the input legs of the LED pair. Now using the two wires from the diodes I momentarily touched one to each of the outer poles of the switch and noted which LED lit up. I tested until I found the wire and switch pole combination that would light the green LED. Once I found the correct combination I soldered the wires to the switch contacts and moved on to the next switch and LED pair repeating the process.
After the switches and LEDs are wired up you then have to make the correct connections to the Tortoise. This involves connecting the common wire to one motor contact and the output wire to the other motor contact. Using my jumpers and clip leads I tested the wires until I found the polarity that resulted in the turnout lining up correctly with the control panel switch and LEDs and soldered them in place. Again I repeated this process for the rest of the turnouts. One good thing about working on 60″ tall benchwork is you can do it sitting in a roll around office chair. Once everything is soldered in place you just flip the control panel down and enjoy the ease with which you can control turnouts. The Charlottesville yard panel allows the yardmaster to route trains past the yard on the mains or into it from one central position in an area about 25′ long. Well, I now have two done and only about 10 more to go–I think I’ll spread them out over the next year or two.
if you’d like to see how I did the panels using accessory decoders and pushbuttons you’ll have to wait for the new book coming out next summer. I’ll also have even more details on these DC toggle controlled panels. It’s never too early to start priming the pump.