DCC Programming tips

Online tools:

CV Calculators

Some help building up the decimal values from the bits in certain CV's

From Digitrax, a CV29 calculator, CV17 & 18 calculator, and some Digitrax specific CV's: http://www.digitrax.com/support/cv/calculators/

There is a general Hex <> Decimal callculator at the bottom of the page


Scale speed calculator:

A nice one from Stony Smith, works in all scales:  http://www.stonysmith.com/railroad/speedcalc.asp

First time setup

Here are some suggestions on setting up a loco:

Make sure your loco is broken in, and well lubricated. Run it for a while to stabilize it's operation.

First try to set up low speed response. Put the throttle in 128 speed step mode. Start the loco, then slow it down to the slowest speed it'll run at. This eliminates the effects of startup friction, and gives a good baseline speed.

Now DOUBLE the speed-step number that's on the cab, and put it in Vstart (CV2).

Now play with CV 2 to try to get the loco to just move at SS1, it may take some playing, but get it so that it moves at ss1, the slowest you can make it.

Some decoders have a "kickstart" setting, a little extra kick to get started, and sometimes it's 2 CV's, so if you have those you can play with them.

Go back to 28 ss moce, and set your loco on the track with one that's set up the way you like it. Consist them together, but leave them uncoupled a few feet apart. Run them up to full speed. Adjust CV5 (Vmax) in the new loco, then try again. Get them close.

If your decoders have CV6 (Vmid) try this at speed step 14. Adjust CV6 (Vmid) to get them close.


Programming locomotives with 2 decoders in them:

Some suggestions from Bruce Petrarca (Bruce, I hope you don't mind my quoting you from the NCE forum)

How to program a loco with 2 decoders in it:
Assume you are working with loco #1234.

Program the motor decoder for a 2 digit address of 34.
Program the sound decoder with a 2 digit address of 12.
Give both decoders 4 digit addresses of 1234, but set them to 2-digit mode (CV29 = 02, for example).

Then, program on the main with 34 as the top of the consist and 12 as the subordinate.

Adjust CVs for each decoder to fine tune the performance. When
happy with the performance, set each decoder CV29 = 34. Now the loco is on 4 digit addressing with both decoders.

If You want to fine tune later, use Ops mode (POM) program loco 1234 CV29 = 2. Now they are separate and you can repeat the fine
tuning, as above. When you are done, tell loco 12 to set CV29 = 34 and loco 34 to set CV29 = 34.

Basic lighting

I'll add some information about setting lighting modes here

Preventing runaways

A suggestion from many people is to set cv29 (DC mode) off, to prevent runaways.

I have found that newcomers might need this, but a runaway is often a result of DC on the rails or bad signal. I use the emergency stop button when needed.

Speed Matching

There are kind of 2 philosophies on speed matching:

  1. Pick the locos that will always run together and match them. Takes no special tools or setup, and just tweak them to work together.
  2. Calibrate locos to a standard.


The advantage of #1 is it takes less equipment and can be a little faster (sometimes)

The disadvantage of #1 is that you cannot mix and match locos whenever.


The advantage of #2 is you can consist ANY locos at any time

Another advantage is that you can calibrate them to a scale speed.

Another advantage is that it’s easy to add another loco to the fleet.

The disadvantage is that it takes a bit more equipment to set up and a bit more discipline to perform.


I use method #2 and I calibrate locos to run at scale speed, according to speed step, i.e. speed step 52 is 52 smph.


So, all locos will consist perfectly AND you always know the scale speed of the loco (on the flat of course, unloaded)


So, first you need to get a DCC meter and set your track voltage and make sure it stays the same. I use the RRAMPMETER from DCC specialties. If you do not do the speed calibration on the same voltage every time, then you won’t get them matched.


Next you need a speedometer to check the speed of the loco, I got mine from Dave Bodnar, in fact I have a wireless sending unit in a hopper car:



The setup with the trackside sensors is fine, just have a small loop.


Now, set a loco to start at SS 1, CV2, to give about 1 smph… if you can’t do that, set CV2 for 2 smph at SS 2, etc.


Then set CV 5 to match what is probably the top speed of the loco, i.e. maybe 70 smph at SS 70, etc.


Normally this is good enough for all locos, remember that when they are connected and under load, they tend to equalize well, testing free running and not connected together is beyond what you need. This is a common misunderstanding, which seems logical, but it’s unnecessary to go that far.


In my case, sometimes I will use a custom speed curve for a loco, but it’s rare that it is needed.


Another reason for a custom speed curve is to “flatten” it above a certain setting. In Z scale, often locos can run 200 smph, and I make a curve that fixes that and stops at 100, i.e. SS 101 produces the same “voltage” as 100… I doubt you will run into this, the above steps are simple and work 99% of the time.



Misc notes

Some early notes on Tsunami programming, will update when I get mine! People are having some difficulty programming on the programming track. That is to be expected, will purchase the soundtraxx booster as they recommend.

All CVs can be adjusted using POM - Programming on the Main. Most DCC systems support POM.

"Out of the box" the Tsunami would come with short address "3". Run on this address and insert the values of CV 17 and 18 using POM that will have to be determined with a CV 17/18 calculator or other means. One such calculator is at: http://www.digitrax.com/support/cv/calculators/

Once CVs 17 and 18 have been programmed, adjust CV 29 so the decoder will respond to 4 digit addressing, example "34" (DC off, normal direction, internal speed table and 4 digit address).

Once "34" has been written to CV 29, the loco NOW will only respond to the long 4 digit address that was entered with CVs 17 and 18.

Chuff cams

SoundTraxx sells a chuff "disc" that goes on the backside of a steam loco driver and be stroked by a wiper. This allows you to synchronize steam chuffs to driver rotation

It's Soundtraxx part number 810038, MSRP $10, available from http://www.litchfieldstation.com/soundtraxx/html/dcc.html

Some people have had difficulties with installation and getting everything to work correctly.

An alternative are the cams and wipers made by Grizzly Mountain Engineering. http://www.grizzly-mountain.com/index.html
They can be purchased from Miniature Locomotive Backshop

They are considerably more expensive than using the Soundtraxx discs, but much easier to install and get working properly.

The most common alternative is magnets and a reed switch, but with many G scale locos, there is a lot of side to side play in the drivers, so many people put the magnets on the tender wheels, which is a crummy solution in my opinion, since they are a different size than the drivers, and also will never exactly sync up with the travel extremes of the piston, where the chuff should occur. The BEMF chuff feature of the QSI shines here.

DCC testers

You can check the DCC waveform on the Power bus with the DCC Pocket Tester made by Pricom. http://www.pricom.com/Trains/DCCTester.html

(note: no longer available, but use the Internet Wayback machine for research in case you come across a used one)

This tester will analyze all your DCC packet information, It has a very handy page that shows at a glance the "health" of your layout with a PASS/FAIL result. Easy to understand.

One of the greatest features of this piece of test equipment is that it can be upgraded whenever the designer releases a firmware change, just by connecting the unit with the supplied cable to your computer and visit the Pricom site and follow the prompts to update your tester with the latest software.

Setting Sound Decoder levels

Here's a suggested method for setting up sound levels to make your loco sound more realistic, posted by Bruce Petrarca (Bruce, I hope you don't mind my posting this)

I set the loco to an idle and read the dB level. I activate the bell
and adjust its level until the reading is 3 dB more than the idle -
indicating that the idle and the bell are about the same level.

I turn off the bell and turn on the dynamic brakes. Again, I adjust
for 3 dB more than the idle.

I turn off the dynamic brakes and run the loco to top speed. I note
the sound level reading. The horn is adjusted to be 3 dB louder than
the prime mover at top speed. While this is less than the 10 dB or so I estimate reality to be, it gives a noticeable horn and fits within the dynamic range of the limited speakers we have available.

NCE - Programming on the main

Programming On the Main - POM allows all CVs to be adjusted while operating on the layout, i.e. while a loco is in operation, rather than putting on the program track. Remember though, you can only set CV's, you cannot read them. To read them back you need to use the programming track.

Adjusting CV2 to match locos in a consist and adjusting sound levels is another useful benefit.

POM address changes are easy. This is a benefit because many combination decoders cannot be programmed on the program track unless you have a booster. Remember, reading CVs is not necessary to program a decoder.

To change the address in POM does require you to alter CV29 so that the decoder responds to 4 digit address. Changing to operate on the long address can be done in a few ways.

Select POM and then select 1 - ADR. You are prompted to select 1 or 2 depending which address you want to change. Then just type the required address number. The C/S does the rest, programs the relevant values into CV 17 and 18 from the systems internal "converter" and adds the require BIT value change into CV 29. It is this easy.

On initial decoder installation/programming you are asked to enter your short and long addresses and the variables for CV 29 the CV for configuring the decoder - direction, DC on/off, speed tables and what address to respond to.

When on the main all you have to do to cycle between short and long address, is to POM, select 2 for CVs, type 29 and change the decimal value to 2 or 34. This will depend on how the decoder is set up in CV 29. Also see page 71 in old manual.

Easier still is selecting POM and selecting 3 - CFG. This will step you through the bits of CV 29 but in plain English requests, direction etc.

Remember if all locos on the layout have short address 3 and CV 29 is set up so that the decoder responds to the long address then when you run a loco out of the box that has 3 and is set up to respond to the short address, not all locos run, only the new one. This is the same for programming a loco with short address 3 with the required long address and then configuring CV 29.

Changing CVs 17 and 18 will require you to know the decimal values from a "calculator" if entering by option 2 - CVs with POM. There are other options that automatically provide the calculation - see above.

NCE - Consists and Momentum

This is not in the manual. If you want to give the consist momentum, then you must select the number of the lead engine, NOT the consist address. Then hitting the momentum button and selecting the momentum rate WILL work. Took 6 months of posting on the NCE forum to get this answer!

Weather Underground PWS KCACARLS78