Thanks for the update and correction to my history of indexed CVs Michael.

But the TCS WOWs are a quite recent product and we developers cannot understand why they came up with such a complex alternative scheme (the actual procedure for programming is quite complex and order-fussy) when there was already a defined NMRA standard.

--?

Dave in Australia?

The New England Convention 2018

On 22 Jun 2018, at 11:12 PM, Michael Mosher <mjmx1@...> wrote:

I think you're being a bit unfair to QSI, they developed their indexing scheme before NMRA had an indexing scheme.? So NMRA reacted to a decoder manufacturer developing an index scheme rather than "anticipated that need".? First QSI equipped BLI loco came out in 2001 or 2002, while RP9.2.2 dated 7/2003 states:
"Configuration Variable 31 Decoder Sub-Address"
"Configuration Variable 32 Decoder Sub-Address Flags"
with note:
"CVs 31-32 are under re-evaluation by the NMRA DCC Working Group.
Manufacturers should contact the NMRA DCC Coordinator before
implementing these CVs."

Also at that time the only Manufacturer Unique CV were 49-64 and 112-128 as 129 and up were "Reserved by NMRA for future use"? (thou some decoders of that time had some CV defined in 129+ range so were technically out of spec but got away with it).? With so few Manufacturer Unique available QSI had to develop an index scheme that fit within the Manufacturer Unique available CVs, to be able to have all the settings they wanted.

So CVs 31-32 became the index CVs after QSI had made their scheme.? Now an argument could be made that QSI should have converted to the NMRA scheme once it was approved, but they did not.

Going back even further, Green Book of DCC dated 3/1997
Listed:
Configuration Data #2 CV31 Reserved by NMRA for future use
Configuration Data #3 CV32 Reserved by NMRA for future use

July 2006 PR9.2.2 does state CV31,32 for indexing, plus expands the Manufacturer Unique to 47-64 and 112-256.