Program a Decoder to run in Reverse

Model Railroader Electronics and DCC
1

Hey group,

I know there has to be a quick fix for this, but I cannot find it. I was installing a decoder in a engine and got the two motor leads reversed so now the engine runs in reverse when its actually in forwards. What CV do you have to program to resolve the problem? Thanks!!

2

with the NCD D13SRJ (last decoder I used) it was CV29

Here’s the manual

go to page 6, near the bottom. Not 100% sure if all decoders are the same though.

alternatively, switch the grey and orange wires to the motor

3

Could you just switch the motor leads to the opposite connections/connectors/pads on the decoder?

Tom

4

There are two ways to do it.

Reverse the two motor wires on the decoder or program CV29 to run the loco in reverse which in fact will run it forward.

Rich

5

Thanks everyone for the replies. Im using an NCE D13SR decoder.

How what would I need to program CV29 to so it will run in reverse but it will actually be forwards?

6

On many decoders adding “1” to the value in CV29 will reverse the engine. So if it reads as “34” and you change it to “35” that should reverse it. Not sure about NCE but give it a try and see.

[;)]

7

NCE decoders work the same way.

Rich

8

Google CV29 calculater or go to Digitrax web site and down load their decoder manual. Digitrax has a table for CV29 settings. Joe

9

rocky,

Dan conveniently provided you a link to the D13SRJ manual above. (Should also work for the D13SR) Click on it. You’re answer should be there. You can also go to the NCE website and download any of the decoder manuals directly onto your computer.

Tom

10

The definition of CV29 is part of the NMRA standard, so all decoders should work this way.

11

Best bet is to read CV29 on the program track. If the value is an even number the decoder is set for normal direction of travel (NDOT) to be forward. Add 1 to make it an odd number and program CV29 to the odd number. The decoder will now run with NDOT in reverse.

If Cv29 is an odd number the decoder’s NDOT is set to run in reverse. Subtract 1 from the even number. Program the resulting even number to CV29. Now the decoder will run with its NDOT in the opposite direction.

This is an NMRA RP so the procedure will be the same for all NMRA compliant decoders.

Martin Myers