Speed tables
#1
I am starting to play with speed tables. I have MRC so I am using their program. I have also looked at JMRI and apparently both use a 28 speed step to do this. I use 128 when running trains. Am I doing something wrong using 128? Or am I missing something here?
Les
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#2
Most guys I talk to at the club say either one of two things - 128 is too fine a graduation (lots of cranking the throttle) to get the loco going or stopping, OR that the decoders tend to be set on 28 steps by default and they don't change it (see first reason).

Andrew
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#3
A lot of decoders do interpolation and the 28 step speed tables work with 128 step mode. Others ignore the speed table entirely unless controlling the loco with 28 speed steps.

If you are using deocders other than a Tsunami, you can use CV2, 5, and 6 in a 3-step table and get close enough speed matchign for MU and get nice response curves for both switchign and road use, and even make it different for say a commuter loco vs a freight loco. Easy to use sliders or not, the 28 step tables seem like more work than necessary, of course some decoder manufacturers have unwisely decided not to impolement all of the other 3. They HAVE to have CV2, but 5 for top speed and 6 for mid speed are optional.

--Randy
Modeling the Reading Railroad of the 1950's in HO

Visit my web site to see layout progress and other information:
http://www.readingeastpenn.com
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#4
So I need to start using 28 step and set CV 2, 5, & 6 For the operation I am seeking? I was not desiring to set 128 CVs, just a little confused. I am just experimenting with it. So far I have had to reset one decoder to factory settings and some how I have fried one.
Les
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#5
I use the "Digitrax three-step". I set CV2 - start voltage, CV5 for top speed, and CV6 for mid-range speed. The "gremlins" inside the decoder take care of the rest. I then set CV's 3 and 4 for acceleration and deceleration. I don't worry about the speed tables. or how many steps they work at... Goldth
Gus (LC&P).
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#6
No, there are 28 CVs to set for a speed table, not 128. With some decoders, the 28 step speed tables only work if you command the loco with 28 speed steps - this is handled by your command station, not the programming in the decoder. Other decoders, even if you send them 128 speed steps, will interpolate values from the 28 individual entries and give you approximately the same curve even though you are sending many more actual steps. There are ALSO 3 step speed tables using CV2, 5, and 6, but not all decoders have that. Tsunamis for one do not have CV5 and 6, and I don't think the MRC onces have the mid speed CV, CV6 - their 'menued' programming system skips setting that so you have to do the option to program individual CV in order to set CV6 on decoders that DO have it - all current DIgitrax, TCS, and NCE decoders support all 3 and you can usually get quite effective response just from those 3. And you do not have to convern yourself with speed steps, CV2,5, and 6 work regardless.

--Randy
Modeling the Reading Railroad of the 1950's in HO

Visit my web site to see layout progress and other information:
http://www.readingeastpenn.com
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#7
I think I understand now. There is actually only 28 sped steps. When I go to 128 The DCC system not the decoder is dividing the 28 into 128.
Les
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