DCC Speed Steps.

[Peterm]

I don't know how I managed to put three up, but there they are. Hope this helps.

the ground pad is the one shown.

[centenary]

Richard at Roads and Rails knows.

https://youtu.be/qaB659yLv5k?si=NECJ9xpz2aD7oAsj

[Bigmet]

All Zimo here, they love to stop and reset...

Root cause analysis time then. I'll not dispute that it takes quite some effort to identify and eliminate all the preventable causes of loss of signal to the decoder; but this done and maintained, there's no need for stay alives. Maintaining now, it's amazing what's 'lurking' in one's train set that surfaces all unexpected after decades of trouble free operation...

[aleopardstail]

All Zimo here, they love to stop and reset...

Root cause analysis time then. I'll not dispute that it takes quite some effort to identify and eliminate all the preventable causes of loss of signal to the decoder; but this done and maintained, there's no need for stay alives. Maintaining now, it's amazing what's 'lurking' in one's train set that surfaces all unexpected after decades of trouble free operation...

oh I pretty much know the root cause, uneven track combined with more frequent cleaning of rails and wheels being needed. I have one stay alive, and its a low capacity home made on in my D49, has basically * all capacity to run the motor but it does work well for the blips in power

[Suzie]

Mine automatically switches. What puzzles me is what would happen if one comes across an older decoder that uses 27 speed steps and a modern DCC controller. Would it run? Or would "Error" come on the display with the error code?

If your controller is sending 126 steps, then the decoder will need to be a modern one or the train will ignore the speed and remain stationary.

If your controller is sending 28 steps, then a decoder will need to be a modern one and have CV29 set correctly to respond with 28 step smoothness, otherwise it will only have 14 steps and will just go to the nearest step to what the controller is sending.

If your controller is sending 14 or 27 steps then any decoder will work fine, but make sure that CV29 is set correctly for the headlight to function.

You will never get an error message, but might get some strange behaviour.

The rule is to always set CV29 for 28 speed step mode, and where possible use 126 steps, 28 steps, or 27 steps in that order until you find what works.

14 step decoders will always respond correctly to 27-step commands and give 27 steps (often what is labelled as 14 steps on controllers is actually 27 steps), but will only give 14 steps when sent 28 step commands.

If you find a 14-step decoder it will be so old and crude that it will probably be due for replacement! 14/27 steps is a very legacy thing, but controllers still support it just in case.