Speed steps and speed match

[JRP]

In reading the many articles on how to consist locomotives using DCC, they tell me to first set my command station to run in 128 speed step mode. I'm using the Zephyr DC50, but am not sure how to tell if I am in this mode. How can I find this out? Does the decoder determine this? Second, to match locomotive speeds, I should speed match them starting at speed stop 1. How can I tell what or where to look for speed steps using the Zephyr? Would a stop watch be the way to go? JRP

[jrbernier]

John,

  Out of the box, your Digitrax Zephyr will default to 28 speed steps.  If the decoder is capable of 128 speed steps, it will interpolate the 28 speed steps generated by the command station and generate 128 speed steps to the motor.  Some really old decoder may be only 14 speed steps or even 28, but most new decoders will generate the 128 speed steps.

  Speed matching is an 'art form'.  Many documents suggest setting the CV2(starting voltage).  With your Zephyr's built-in throttle, you really can not do this as it is just a potentiometer and not an encoder(and the display really does not show your speed steps).  I have a Zephyr here in the 'man cave' and I use a DT400 throttle and JMRI to do my speed matching.  The best you can do with the built-in throttle is to keep increasing the value of CV2 until the engine starts to move as you crack the throttle.  You really have no idea if that is speed step 1 or speed step 2....but it will be close.

  Myself, I use a DT400 throttle set to speed step 1 and JMRI to adjust the value of CV2 - fast and safe way to do this stuff.  

Jim

[rrinker]

 Zephyr default mode is 128 speed step, not 28. OpSw 21, 22, and 23 control the default mode (Page 47 of the manual), the default is all thrown, for 128 speed step mode.

        --Randy

 

[selector]

You know, Jim and Randy,  it does me aged heart a lot of good to see differences in opinion and statements of fact on this electronics forum.  I think I have a good handle on much of the hobby, but a number of good men keep humbling me by pointing out deficiencies in my understanding, or they point out defects in my expression of my understanding. 

I am a happy man that you both contribute to this forum.  Please don't let little setbacks throw cold water on you and prevent you both from continuing to post frequently.  I read all your posts.   I'm a big fan, too.

Crandell

[JRP]

Thanks for explaining this Jim. I do have a DT400 throttle as well and will work with that adjusting CV2. Fortunately the loco's I am trying to consist have the same decoder manufacturer (QSI) for A-B units so hopefully they should respond to the same adjustments.