In DCC, what is the difference in the 3 step and the 28 step speed table as far as the operation of the engine is concerned?
JaRRell
The higher the number, the finer the control.
with 12 step it usualy takes 12 notches to get too full speed and 128 it takes 128 notches of throttel to get too full speed of the loco. SO baisicly Road Loco’s would be like 24 or somewhere like that depending on the system. while switchers would be higher number be cause the tend to need too be more precise.
Ok thanks guys.
JaRRell
i think you mean cv #67-94 Individual Speed Table?
kon
Hmmmm… not sure about that. It’s the speed tables referred to when programming CV 29.
JaRRell
Get yourself JMRI Decoder pro, it is FREE. This will take out the mystery of CV29. As far as the speed steps, the CURVE that the steps are set at is as important as how many steps are used… You can go 28 steps with decoder pro and an analog curve and get the prefect balance of High and Low speed. I am still learning this and amaze myself everytime I play with CV29.
Thanks George. What are ‘most’ decoders ,that are in the engines we buy, set for when they come from the factory?
JaRRell
Practically every decoder today defaults to 28 speed step mode. The old 14 speed step mode was used by early decoders but I don’t know of any manufacturer today who still makes 14 speed step decoders.
The question about setting bit 4 of CV29 has to do with whether you want to use the default 28 speed steps that are in the decoder, or if you want to use a custom speed table that you have created by programming CVs 67 through 94. In order to set bit 4 to a value of 1 and use an alternate speed table, you would add 16 to the value programmed into CV29.
The so-called 3-step table resets the values for Start Voltage (CV2), Maximum Voltage (CV5), and Mid Point Voltage (CV6). Most decoders have a default value of 0 in these three CVs.
If you can get your locos to respond properly just using the start, mid, and top settings, by all means. Using the 28 step speed table is a good exercise in learnign patience if you try to program them by hand. This is definitely one of those times when DecoderPro is invaluable - you simply drag the line to for the response curve you want and it sets allt he CV values for you. Doesn;t guarantee it will be perfect the first time, but it DOES mean you don’t have to tediously step through 28 CV numbers and key in values.
–Randy