KB354: Programming MRC Sound decoders in OPS mode ('on the Main') using Hexidecimal conversion for CVs 17 and 18

This article was last updated on Jan. 31, 2012, 2:28 p.m. | Print Article | Leave Feedback

Editor's Note: This tech note has nothing to do with Digitrax SoundFX sound decoders.

This is for users who have Digitrax command stations / boosters / etc and wish to program MRC sound decoders.


 Due to low programming track power in certain dcc systems, programming sound decoders on the program track may not be possible, especially trying to assign the decoder a four, (4), digit address.

This programming procedure has to be performed on the mainline, where more power is available for programming sound decoders.

If your dcc system allows simple 4 digit address programming on the main, [ops mode programming], then simply input the 4 digit address and press “ Enter”.

A second step might be needed for certain sound decoders, which would be activating the 4 digit address by changing the value of CV#29.

Inputting a value of “34”, [constant], tells the decoder to use the 4 digit address.

Some dcc systems need to have CV#’s 17 and 18 programmed separately to assign the decoder a 4 digit address.

You can not simply split the four digit address in 2 halves and input these into CV#’s 17 and 18.

A conversion from decimal numbers to hexidecimal numbers is required.

Once the hexidecimal conversion for the 4 digit address is performed, this number is then split in half and then each half is inputted into it’s respective CV, [17 and 18].

To perform this operation you need a scientific calculator or the calculator accessory on your computer, [make sure your p.c. calculator is set for the scientific mode].

Using the “constant” number of “49152”, add your 4 digit address to this number For example let’s say your 4 digit address is “1998”.

You add 1998 to 49152, which equals 51150, [1998+49152=51150].

Under the “DEC” setting, input the number “51150”, or the number you came up with after adding it to the constant number of “49152”, then change the setting to “HEX” You will get a hexidecimal number of “C7CE”, [51150 decimal equals C7CE hex].

Split this number in 2, [half], which gives you 2 separate hex numbers for CV#’s 17 and 18.

C7 goes into CV#17, and CE goes into CV#18, but first you have to convert these 2 numbers back into decimal values to input them into the CV’s.

Enter “C7” into the calculator under the Hex mode, then switch the calculator’s setting back to decimal, you will get the following number…C7, [hex]=199, decimal].

Input the value of “199” into CV#17.

Enter “CE” into the calculator under the Hex mode, then switch the calculator’s setting back to decimal, you will get the following number…CE, [hex]=206, [decimal].

Input the value of “206” into CV#18.

This gives the decoder a 4 digit address of “1998” The next step is to go to CV#29 and input the “constant” number of “34”, [decimal].

This number tells the decoder to use the 4 digit address, along with analog disable, 28/128 speed steps, and normal direction, [locomotive forward].

There are other constant values that you can input into CV#29 to change the decoders parameters, please refer to your decoders instructions, or to our “CV#29 Table”, which can be found on the MRC website under “Prodigy Info Page”,

In that case please go to the MRC site and search on the term 'CV29' or you may call them at 732-225-2100.

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