KB235: CV29 - Speed Steps

This article was last updated on Jan. 13, 2012, 9:59 a.m. | Print Article | Leave Feedback


CV29 is assigned a single value which chooses a combination of specific effects:

1. Speed step control.

2. Speed table On or Off.

3. Analog mode conversion On or Off.

4. Normal Direction of Travel (NDOT).

5. 2 digit addressing or 4 digit addressing.

Speed Step Control.

There are two modes for speed step control: Standard (14 speed step mode) and Advanced (28/128 speed step control).

Because of differences in the capabilities of DCC compatible command stations and decoders, you may have to set CV29 in your decoders to different values to match the mode of the command station you are using.

In earlier times, some command stations were only able to issue 14-speed step commands; these command stations are now the exception rather than the rule.

Likewise, most mobile decoders now operate in 128-speed steps, although there are some which operate in 28-speed step mode.

If your command station is sending standard 14 speed step mode commands, your decoders must be programmed for standard mode in CV29.

If your command station is sending advanced 28/128 speed step commands, your decoders must be programmed for advanced mode in CV29.

All Digitrax command stations and decoders are 128-speed step capable and we recommend that for best performance you run them in 128-speed step mode.

If you are using non-Digitrax decoders that are not able to be programmed for advanced mode and you want to run your command station in advanced mode, you can "status edit" the standard decoders so that they can be run with your command station.

Status editing is done at the command station, setting up special performance settings for an individual mobile decoder address.

In this way, you can still operate a locomotive with an older 14-speed step decoder on an otherwise current-technology model railroad.

If, at a later date, you convert that particular locomotive to a modern decoder, you will discover that the locomotive accelerates in "leaps & bounds" because the command station still has that specific address status edited for 14-speed steps rather than the 128-speed steps which the new decoder uses.

You can then status edit that address back to the conventional 128-speed step setting.

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