Here is a summary of posted info I have on the R2LC and the codes. Jon Z provided some more details and the #3 is explained. Still no specific info. Not sure what difference the Inverted non inverted or Serial on or off in conventional does. Most of this was for the 1999 coding. I imagine most has to do with Railsounds as far as the inversion or serial off. I know the 28000 series had either Signal Sounds or RS, and some where upgradeable and others came fully command. My 28000 have Code 7 R2LC and they respond to AUX1 8-9 for smoke. I know an early post said Code 07 don't have that capability, but mine do. G
All told there are a total of 7 R2LC's that were produced thus far.
They are as follows;
C04 (early modular TMCC locos and command ready modular boards)
C05 (used exclusively in the Lionel Backshop)
C06 (used in the later TMCC steamers (such as the later semi scale pacifics and hudsons, after the whole motherboard issues were corrected)
C07 (used initially in the C-420's only, but then used by licensees) Also used in the 28000 Series
C08 (the most common, produced in the largest number, compatible with all aftermarket upgrade boards, this is the board pretty much everyone uses; Atlas O, 3rd Rail, Weaver, K-Line (even the new SD70MAC's!, etc. the C08 board is also the one that will be sent to anyone who orders an R2LC from either us or DD.)
C08 board will sub for a CO7, but you need to reverse the marker light polarity.
C11 (used in newer RS 5.0 locos with Odyssey)
C13 (U33 now the most current R2LC, used in all new production Lionel stuff with RS 5.0 and Odyssey)
While I really cannot comment on the differences internally with the software I can tell you that there are some (a very few at that) C06 boards with tunerless pots in circulation. Most all C04's, C06 and C07's have tuner pots (shiny metal adjustable frequency potentiometers) that can easily come out of tune to the 455KHz TMCC frequency if bounced around in shipping, etc. There are some C07's, all C08's, C11's and C13's have tunerless pots, meaning they withstand the bounces in shipping and are fixed to the 455KHz frequency.
Early C04, C06 and C07 boards do not support the AUX1 + 8 feature in the program mode (to turn smoke on/off at 12VAC constant) the Late C07, C08, C11 and C13's do support the AUX1 + 8 program feature.
R4LC boards are for Legacy engines with the quilling whistle.
R6LC are used in Vision engines with more options.
STEAM
7 = Serial Data “UN” Inverted. Keeps serial data on in conventional
4 = Front Headlight on all the time; Rear light directional
0 = Inverts serial data from R2LC to RailSounds
DIESEL
8 = AUX 9 Boost for Smoke (14V versus 12)
6 = Smoke out as CAB Light
5 = Smoke Output as pulsing Strobe
7 maybe for IR Tethered engines
3 for wired harness??
This was provided by Jon Z:
;SET OPERATING MODES
;(ONLY COMES HERE IF VALID ENGINE AND PROGRAM SWITCH IS ON)
;NOTE: THIS SECTION WAS REWRITTEN TO INCLUDE AUX1-8 AND 9 ON 3/22/99 BY RL.
;USING THE MODES BELOW, THE INVERSION ONLY TAKES PLACE IF AUX1-0 IS THE LAST
;COMMAND ISSUED. I.E. 7-4-0 WILL ENABLE COMM IN CONVENTIONAL, BE PUT IN STEAM
;MODE, AND INVERT THE SERIAL COMMUNICATION CHANNEL.
;NUMERIC 0 = INVERTED COMM OUTPUT
; 1 = STEAM MODE, NORMAL COMM., WORKING LIGHT
; 2 = DIESEL MODE, NORMAL COMM., AUX TRIAC
; 3 = DISABLE SERIAL COMM IN CONVENTIONAL (EXCEPT CHUFFS)
; 4 = STEAM MODE NORMAL COMM.
; 5 = DIESEL MODE, NORMAL COMM, MARS LIGHT
; 6 = DIESEL MODE, NORMAL COMM, CAB LIGHT
; 7 = ENABLE SERIAL COMM IN CONVENTIONAL (SEND DIRECTION COMMANDS)
; 8 = DIESEL MODE, NORMAL COMM, SMOKE CONTROL
; 9 = NOT USED