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Operating on a programming track

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  • Member since
    December, 2017
  • From: Buffalo, NY
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Operating on a programming track
Posted by Lonehawk on Friday, February 09, 2018 3:30 PM

Hi folks,

Quick (I hope) question about DCC.  I want to use a track in my engine yard as the programming track.  When not being used as a programming track, I'd like to have it pull double-duty as a spur to park a gondola for emptying the ash pit, and periodically, I'd like to be able to pull a loco onto the spur to swap the gons.

Would I be able to run a loco on the programming track, as well as programming it?  Does it depend on the DCC system I get?  I know how to get around the problem if I can't run and program on the same track, but I wanted to check while everything's still on paper, and easily changed.

Thanks.

When all else fails, wing it!

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Posted by Onewolf on Friday, February 09, 2018 3:44 PM

You could use a DPDT switch to select between DCC programming output and DCC track power output to that section of track. 

But.... best practice is to have a 1+ locomotive length of completely dead track between your DCC layout track and your programming track to avoid accidentally having a locomotive create an electrical bridge between the layout track and the programming track. 

Modeling an HO gauge freelance version of the Union Pacific Oregon Short Line and the Utah Railway around 1957 in a world where Pirates from the Great Salt Lake founded Ogden, UT.

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Posted by bandmjim on Friday, February 09, 2018 3:44 PM

Try info on this site  http://wiringfordcc.com/track_2.htm#d2  if you can follow.  Bookmark the home page as there is a lot of useful info found here.  Hope this helps.

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Posted by DigitalGriffin on Friday, February 09, 2018 3:44 PM

The way it's typically done is have a section that is isolated at both ends and attach the track leads to a DPDT (Double Pole Double Throw) Switch.  One set of leads go to program track output of command station.  The other set of leads go to the main track leads.  When you want to program, you move your loco to that isolated track throw the switch up to "Program".  Most command stations shut down the main if you are doing program track programming.  But be careful and make sure you don't cross both sections at the same time when you throw the switch!

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

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Posted by MisterBeasley on Friday, February 09, 2018 3:45 PM

The simple answer is "Yes."  I have just such an arrangement.  As long as your DCC system has separate outputs for normal track and programming track, it's pretty easy, and actually a preferred way of doing it, because you don't have to handle the locomotive to move it to a different track for programming.

The track should be electrically isolated from the rest of the layout.  Then, run feeders from the center posts of a double-throw, double-throw toggle to the track.  One set of outer posts goes to the normal outputs of the DCC system, and the other set to the programming outputs.  Done!

This is on my Lenz DCC system.  On my system, only one set of outputs can be active at a time.  Other DCC systems may vary, and if that's the case with yours, you should consider a dead zone between the programming track and the rest of the layout so you can't accidentally connect the two.

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Posted by Arto on Friday, February 09, 2018 4:35 PM

Another thing to consider is many (most?/all?) locomotives tend to move as the decoder is read/written to. One or two programming changes won't be enough to make the loco move very far. But if you're reading all of the CV from, say a newly acquired loco - just you know what you've got, it could take a long time to read all the CV and the loco may move several feet in the process.

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Posted by peahrens on Friday, February 09, 2018 5:27 PM

An important watch-out with the DPDT setup is that you may do some programming and then bridge the switchable program track to operating track.  Either by your programming loco being at a rail joint or also another way.  I have more than once left the DPDT for program, removed loco from the track, then run another loco into the zone.  That puts ops power backward to the system program outout, as the loco wheel bridges the rail joint, potentially bad news for the system program output circuitry.

I looked into the fancy 4 pole switch setup, with isolation zones.  Someone at Tonys advised me that my 5A NCE could get fried, otherwise.  But the NCE folks assured me not problem with my Powerhouse Pro.  It shuts off ops power when program output is selected, so ok if  loco being programmed bridged the gap to the dead ops zone.  Not an issue. 

But if the DPDT is left in program position and the system is in ops mode, an external loco coming to the joint would feed ops power back into an "off" program circuit.  I think I understood from the NCE folks even that was ok but I wonder if we discussed that scenario or if my setup is still vulnerable (vs. the 4-pole setup with isolation tracks).

The point being, the degree of conservatism may vary with different systems.  Or at least understand the issues before hooking up.  BTW, I bought one of those 4PDT (maybe center off) switches and it is interesting to find the right ones.

Do plan on making mistakes, like running a loco from the opers track onto the program track when the DPDT is still in program position.  I've done it.

Paul

Modeling HO with a transition era UP bent

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Posted by Lonehawk on Friday, February 09, 2018 5:33 PM

bandmjim

Try info on this site  http://wiringfordcc.com/track_2.htm#d2  if you can follow.  Bookmark the home page as there is a lot of useful info found here.  Hope this helps.

 

 

Ugh.  I can’t believe I forgot about that.  Thanks for the reminder.  Between that and the rest of what’s been said here, it seems I have my answer.  Thanks, all.  

When all else fails, wing it!

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