Thanks to NCE Super User Dave Heap for helping with this topic.
***Important Note** For the Powerhouse, Power Pro, PH-Pro, and CS02, you must use OPS mode programming / (POM) Programming On the Main to make indexed CV changes. If you have a Power Cab system, there's no problem. It doesn't have a firmware problem.
Soundtraxx video on YouTube - https://www.youtube.com/watch?v=nv2XFr60zwg
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Think of a row of three file cabinets. Each cabinet has three drawers labeled 1,2 and 3. Since you have three different filing cabinets, you must specify which one you want to use first.
The index sets which of those three things you are referring to.
Example: For CV 2.257, you set CV32=2, then configure CV257.
If the setting is CV 3.264, you set CV32=3 and then CV264.
if the setting is CV 2.512, you set 31 to 16 , then set 32 to 2, then set 512
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CVs with a dot (1.300) are “Indexed CVs,” which is a fancy way of saying they are a group of three CVs that need to be changed like a combination lock.
The first two numbers “unlock” the CV you need to program. The third number is what you are changing.
- Ensure CV 31 is set to a value of 16.
- Enter a value of 1 into CV 32 to select Indexed CV Page 1.
- Select CVs 257-512 from your command station.
From page 13 of the attached Soundtraxx manual:
Indexed CVs The term “indexed CVs” tends to cause confusion and consternation. Indexed CVs are located on ‘pages’ to help manage the total number of CVs. The NMRA DCC Standard requires this and works like this: Indexed CVs are accessed using two CVs: CV 31 enables indexing when set to a value of 16 (the default value), and CV 32 selects the desired indexed page. You do not need to type “1.” Into the command station when programming indexed CVs. Because of the features and options in Econami decoders, three pages of indexed CVs are provided: To access CVs 1.257-1.512: 1. Ensure CV 31 is set to a value of 16. 2. Enter a value of 1 into CV 32 to select Indexed CV Page 1. 3. Select CVs 257-512 from your command station. To make things easier, Econami CVs are grouped by function as follows: CVs 1.257-1.512 are used for configuring Flex-Map function mapping CVs. CVs 1.257-1.384 are used for function mapping CVs, and CVs 1.385-1.512 are used for automatic effect configuration. Refer to “Configuring Function Mapping” for more information.
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Indexed CVs (and Power Pro)
Indexed CVs allow for more than those available in the range of 1-1024 inclusive (a limit set by the DCC packet standards in S9.2.1). Many of these are already reserved for particular purposes.
However, the NMRA standards covered that need and provided a way to allow for many more CVs. This is intended to be done by a page indexing system for CVs in the range 257-512 inclusive, allowing for more than 16 million CVs.
The NMRA standard S9.2.2 covering Configuration Variables defines the following:
- CVs 1-256 (inclusive) and 512-1024 (inclusive) are to be treated as normal CVs.
- CVs 257-512 (inclusive) are to be treated as paged index CVs, with the page number stored in CVs 31 and 32 (the index registers).
This means there are a total of 65,536 possible pages of CVs 257-512, so you need to set the correct values in the index registers before accessing any CV in this range.
In JMRI, we chose the convention "CV a.b.ccc" for these NMRA-compliant indexed CVs, where "a" is the value to load in CV31, "b" is the value to load in CV32 and "ccc" is the desired CV number (in the range 257-512) on the page specified by "a" and "b" combined.
QSI-indexed CVs predate the S9.2.2 indexing specification and use CV49 alone or (CV49 & CV50) as sub-indexes to several other <257 CVs.
ESU implemented indexed CVs per NMRA S9.2.2, so CVs like 16.2.384 are included in these decoder definitions.
ZIMO also followed the NMRA speciation.
SoundTraxx has implemented S9.2.2-style indexed CVs in its Econami and Tsunami 2 ranges. However, they use a fixed value of 16 in CV31, so they only quote it in CV32. Thus, you will see CVs like 1.257 in these decoder definitions.
TCS adopted an even more complex system using CVs 201, 202, 203 & 204.
It is important to realize that indexed CVs are still just CVs in your DCC system. It knows nothing about indexed CVs.
But several issues have arisen:
1) Some DCC systems have problems with CVs>256. For example, I discovered an issue in the NCE Power Pro firmware that causes the wrong CV to be written in Program Track mode for any CV>256.
2) some decoder brands may have problems processing indexed CV calculations inside the decoder within the timing specifications of the NMRA standards. This could cause issues with some DCC system brands/models.
3) ESU and ZIMO both provide in-decoder workaround solutions for problem (1), and we have successfully used the ESU algorithm in Decoder Pro. (However, ZIMO provided different solutions with different firmware, and as yet, no volunteer has found time to resolve this.) Unfortunately, SoundTraxx has not provided a similar workaround for its decoders.
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