Re: programming CV

Tom G.


Thank you. Very informative. Good info to save. 


On May 18, 2019, at 6:11 AM, Brian Lewis <brian@...> wrote:

Oh Gosh! This is going to stir up a can of worms.

If you do not know what you are doing, then leave the decoder at the manufacturer's default settings - it should run well at these settings. But you will probably find that the acceleration/deceleration and the top and mid speeds are not what you want.  So proceed cautiously as follows, noting every default and changed setting, as you go. Be sure you know the CV number and value that returns the decoder to its default setting. It is your layout, so do what you want, but this is how I begin.

First I look at the top speed - CV5. It is probably set at 0 or 255 and for me, is too fast. I have 30+ locos and on these no CV5 is set above 120.

Then adjust CV6 - the mid speed. I normally set it at around 40% of the value of CV5, e.g. if CV5 is 120, then CV6 will be set to 50.

Then consider acceleration/deceleration. Generally speaking, you want the loco to slow down slightly quicker than it accelerates. As my layout is essentially a 26 foot shunting plank, I use 3 for acceleration - CV3 and 1 for deceleration - CV4.

How does the loco start on control setting 4? (You are using 126 speed steps aren't you, rather than 28)? At this setting the loco should move away prototypically. If not, set CV2 to 40, test it and then adjust up or down until you are happy.

Really until you have gained some knowledge you should leave everything else alone.  But in truth I do adjust other CVs, as follows, basically because most of my locos are old and are not equipped with modern motors.

CV9 adjusts the EMF sampling rate. I start at a setting of 88.

CV56 adjusts the PID control. I set this at 99.

CV57 deals with track voltage. I set this at 140.

CV58 can improve mid speed performance, I set this at 200.

CV65 adjusts the 'kick' rate at startup. I set this to 25.

CV116 sets the kick rate. I set this to 2.

CV117 sets the kick strength. I set this to 25.

CV123 helps prevent jerky starts. I set this to 24.

Now I stress yet again, these settings work for me. I am as equally sure there will be folk out there who will be horrified at this. So, as 'tit for tat' emails, (which this elist does specialise in occasionally), bore me, this is my one time comment and I will leave others to add as they please.

My final piece of advice is to search the Internet for JMRI and Decoder Pro. I do all my adjustments via a computer, which not only makes adjustment, but also stores your settings.

Have fun.

On 18/05/2019 00:11, leenbeau@... wrote:
What are CV's and how do I program them ?

Regards and thanks


Brian Lewis

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