this may sound like a dumb question...I recently aquired a Digitrax DCS100 & DT 400 throttle. It works fine..operating my small layout & locos..my question is...
I have the layout attached to the Track A & B terminals & a separate piece of track to the PROG 1&2 terminals
What programming setting do I need to use to program a loco on the programming track without affecting any loco(s) on the layout?
Well, I use JMRI and a PR4 (and a PR3 before that and an MS100 before that) to program, so I've never had to use any of my DTxxx throttles for programming tasks.
But basically, once you enter programming mode on a throttle (See the DT400 manual for details), the DCS100 is "smart" enough to send programming commands to the programming track only, without disrupting anything that's going on with the track outputs.
In other words, once you're in programming mode on that throttle, program away with that loco on the programming track. Your mainline won't be affected in any way.
EDIT: Unless, of course, you select the "PO" (Programming on the Main) mode on your DT400!
Digitrax supports four programming modes: Paged, physical register, direct, and operations mode. Operations mode is the only one that writes commands out to the main track, so any of the others will only affect the loco on the programming track. Paged is the default Digitrax mode and the only one I've ever used other than operations mode.
On the DT400 throttle, the modes are represented as PG (really P6, they use a 6 to represent the G) for paged, PH for physical, Pd for direct, and Po for operations mode.
That being said, Operations mode can be very handy. It only sends instructions to the locomotive that you have selected, so other locos on the layout will not get programmed. Once you have a loco's address programmed, you don't have to keep moving it to the program track if you want to make additional changes. Just make sure you do have a loco selected and that it's not '0', because in those instances it sends the commands to the broadcast address and will program everything on the layout.
Hit program button till it reads DIR, you are then on program track only.