Re: DCC System Recommendations



The number of slots used are a function of how the locomotives are consisted.

For example, simple consisting is where all of the units in the consist have the
same address.  This would take up one slot.

For Advanced Consisting, or Decoder Assisted Consisting, all of the locomotives
are slaved to a virtual two byte address. (0-127).  If there is 1 or 100 units
in the advanced consist, this takes up only 1 slot.

For Universal or Controller based consisting, the Super Chief handles the
consisting and uses one slot for each member of the consist. So a 10 locomotive
lashup would use at least 10 slots.

Digitrax has an address range of 9983 I think for locomotives.  It is a little
less than 9999, I know that for sure. But that does not mean it can control any
more than the number of open slots.

As for the locomotives parked in the yard etc, do not use any slots if they have
never been accessed by a throttle. For example, if I place a locomotive in a
fueling platform by palcing it there by hand, it never gets a slot allocated
until I select its address to issue it a command. Once I select the address a
slot is consumed.

As far as the permanentcy of the consist, simple and advanced stay cosisted
untill you place them on a programing track and change them.

Universal consists last until they are cleared from the controller. If you were
to take those locomotives to another layout with a different controller, they
would not be consisted. It is the use of the universal consists, and not
properly dispatching them that holds the used slots. At some point you will see
a message "slot max" which means all 120 slots are taken. Unless some of the
addresses are purged, no new locomotives will be able to be used.

I hope this clears things up for you!



From: movnscaler <captn_chip@...>
To: WiringForDCC@...
Sent: Sun, January 2, 2011 5:17:38 AM
Subject: [WiringForDCC] Re: DCC System Recommendations

In your previous post you wrote,"Digitrax can only control 120 slots for
locomotive addresses." This seems like an important point for our layout.
Specifically, if the head end power for a train is a consist of five locomotives
do you know how many of those 120 addresses are being used (i.e. 1 or 5
addresses)? Second, if there are locomotives in the yard that are available for
use, but are currently sitting idle, do those locomotives soak up additional

I'm trying to understand what this limitation means from an operational point of
view. While we have way more than 120 loco's, I can't imagine a situation where
there would be more than 120 loco's on the layout at one time. My estimated
worst case is +/- 30 loco's operating simultaneously (most in consists; some
individually) with an additional 30 to 50 loco's scattered around the layout in
yards and sidings (idle but available for use). I have to imagine this works,
they use the system for the really huge convention layouts . . . right?

OK, Digitrax allows up to 9000 locomotive addresses (correct me if I've got that
wrong). Can any of those 9000 locomotives (once programed) be added or removed
from the layout without additional programming? And, once 4 or 5 loco's are
consisted together do they remain a consist even if they are removed from the
track put in their boxes and then placed back on the track weeks latter?

I'm sure these are elementary questions, thanks for your patience.

--- In WiringForDCC@..., David Eaton <dcesharkman@...> wrote:

I have been a member of 2 NTrak clubs that used Digitrax Super Chiefs without
any issues on large layouts.

Where Digitrax excels is the use of LocoNet to have an alternate communication
network to the accessory devices like the stationary decoders and occupancy
detectors and signals. Depending on the complexity of the club layout, this can

be a great advantage especially if your club does nmore than just loop
activity.  LocoNet makes it easy to wire up a command bus as well as a

throttle bus.

This advantage is not available directly from NCE, but can be used with NCE by
using a few non-NCE products.

Depending on the size of the club, and how many locomotives will be operating
may be the ultimate determining factor. Digitrax can only control 120 slots for

locomotive addresses. Depending on how your club plans to handle consisting,

may run out of space in a hurry. I do not have access or have ever used NCE so

am not sure how many active addresses it can handle.

So the one of the real decision makers in the system will be the scalability to

handle the number of members and their locomotives.


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