Projects

We currently have one large project in progress.  As we get closer to completion, some of the documentation will be made available here as changes are inevitably made.

Current

Signal System
Project startup: The project was conceived in late 2005 and a proposal in 2006 for a prototypical style of track-side
signal system was made.  Keys points below describe the system.

• Be controlled by computer rather than "canned" hard logic for flexibility and scalability
• The system would depend on LocoNet connections to all devices affecting the signal system and thus was
  a substantial investment of available funds for the next three years

Hardware: 

• Digitrax^® PM4x power managers are used for DCC power circuit protection and reversing control
• Digitrax^® SE8C's were used to drive the signal masts
• Detection is performed by two RR-Cirkits^® TC-64 Tower Controllers and ten BOD-8 detector cards
• Tortoise^® and SwitchMaster^® motors are used to remotely operate turnouts

Software: 

• A Pentium^® 4 powered low-profile computer was loaned to the club at the beginning of the project to build
  up the signal logic programming without investing any money in the computer itself
• Signal system logics are controlled by Railroad & Company's TrainController v. 5.8 F1.  Though its original
  design was to control trains automatically, it suited our needs for signal control perfectly.  An early candidate
  application was PanelPro by JMRI™, an open-source design application for model railroad control.  However, the
  time to "build" the layout through entering the coordinates of track elements took so much time that it was
  placed as the alternate control program base instead.

A few terms we used while researching the operational theory and considering hardware candidates.  While we don't
know if we coined any of these terms they suited the need to identify key assemblies or modules of the system we
were designing in 2005-2006.

PSM - Power Supply Module -        Designed in 2001, this module contains a power supply and booster with a terminal
                                                block to split the track power output and ground of the booster into multiple branches.

PDM - Power Distribution Module - Module containing power management devices such as the PM4x.  Devices connected
                                                to terminal blocks ease connections with the layout electrical system and inter-
                                                connects with the PDM above. A number identifier (PDM-II) refers to the number of
                                                PM4s onboard. A "+" sign indicates a signal controller is present while an R designation
                                                indicates that one or more reversing sections are supported.

SCM - Signal Control Module -       This was originally designed as a standalone module contains the Signal Controller (SE8C)
                                                with terminal blocks for connections to local turnout controls and power interconnects.
                                                Ten conductor flat ribbon cable is used to connect to the signal masts from the 10 pin
                                                headers onboard.  Digitrax^® TSMKs (Terminal Strip Mounting Kit or Terminal Signal Mast Kit)
                                                is used to connect hand made signal masts with free wire leads to the ribbon cables.

PM4x - Digitrax Power Manager 4 - The power manager established during the conversion to DCC in
                                                 March of 2002 was a PM4.  Digitrax has since upgraded the product to include some
                                                 added benefits.  The original PM4's were not upgraded as we did not benefit from them.
                                                 because of the upgrade and designation of PM42 by Digitrax, we use the term PM4 or
                                                 PM4x in general.  Later, a modification of the PM4s will be made to reduce the false
                                                 short-circuit detection from newer sound-equipped locomotives that put a large surge
                                                 current through them.  There are other power managers but none as far as we have
                                                 seen, connect to the LocoNet, for troubleshooting and electrical system status feedback.

Diagrams

Below are a few diagrams or drawings of our equipment.  Photo's are included for a visual comparison when available.

PSM - A simple design to divert booster output to multiple sections of the layout or track.  This was
        designed in 2001 for our initial conversion to DCC.  However, we were able to install a single PM4
        onboard to create a complete power distribution module.  This was more efficient as it turned out.
        Eight of these were built to break the layout into 8 distinct power districts.  These districts were
        further broken into smaller, manageable "sections" or sub-district groups of track. 

        The PSM design shown here is used in only one location on the layout due to the size of the area
        covered.  The PM4's for our Blue district are in two different locations.

PDM - As the DCC system has evolved, so has the PDM.  PM4's were included in all original PDM designs
         but extra PM4's were installed as satellite power management where needed.  The signal project
         has required us to increase the number of sub-sections for the detection system to detect trains
         in individual signal block sections.  We did not use one section of a PM4 to a single section of track
         unless the shorting of one track adversely affected train operations in another.  In effect, each
         section of a PM4 provides short circuit protection for one main line section and an adjoining siding
         section or spur or lead of lesser importance.  This minimizes the impact on main line running.  Where
         it does double up with a lesser section, that section would typically need use of the main line or siding
         there for switching and thus does not impose electrical conflicts where it can be eliminated.

Standard Configuration                                 "Plus" Configuration featuring on-board signal controller

SCM - The Signal Control Module was originally designed as a stand-alone module like the others.
         However, plans change when it became reasonable to expect the new PDM's would be placed
         in the new center of their respective power districts which, by design, match up with most of
         the signal districts.

We do not use the built-in detection system on the SE8C as it requires an
"active low" signal.  From the start we wanted to use inductance detection
instead of diode detection so as not to rob power from the track and possibly
cause interference with LocoNet communications.  Many argue against this
point of view however, as they do not have issues much of the time. 
Since throttle panels steal power from the track to power plugged-in throttles
and the track power indicator, we decided to have one less item stealing track
power for occupancy detection.

RR-Cirkits^®

We use two of their Tower Controller 64 devices to generate occupancy message
packets over LocoNet to Railroad & Co's TrainController^® software application.
Below is a drawing of our first design consideration.

The parts of our detection system below. 

TC64                                                        BOD-8                                    Current Detector Coils

We use CAT-5 network cable as it bundles four pairs in a single jacket.  This is ideal for connecting the coils to the
BOD-8s in groups.  The same 10 conductor flat ribbon cable the SE8C uses for their signal connections also work
with these devices which can save money with "like parts" and on-the-shelf redundancy.
It's an excellent design and easy to tune, this system is the best induction detection system we've found!

As a side note, we will also use the TC64 to control the turnout control panels mounted around the layout.  With
this set up, the dispatcher will be able to deactivate/activate the local turnout switch panels for train crews
performing switching moves requiring the main line.  This will also prevent visitors during open houses to operate
the turnouts.  Each operator will carry a key to unlock the panel locally when a dispatcher is not present.

LocoNet Topology

Once our hardware was decided upon, we had to come up with a LocoNet design that could
be redesigned as we made progress in the signal project and still keep the trains running.
The entire DCC system was revamped as we progressed.  This was the first requisite to
installing signals.  We had a few issues with the system as it was so we made it better
the second time.  The LocoNet wiring wasn't any different so we had the chance to rework
it as well.  Below is a diagram showing an example of a "chained star" network topology. 

Our system incorporates a segregated network.  This means we have separated the
booster network from the rest of the system by using cables using only the ground and
RailSync lines.  Boosters do not use LocoNet signals.  All other devices use LocoNet
and ground lines for communications.  We are modifying our LocoNet by connecting
the track power indicators of each panel to the track which will supply power to the
throttles via the panel diode network. This of course is the only device we will allow
to "steal" track power.

Another modification that can be made to the LocoNet system is detailed in RR-Cirkits
notebook of information online at http://www.rr-cirkits.com/Notebook/index.html
Look at the item titled: "LocoNet wiring to add external power"  This is our ultimate goal.
We did run into one issue when this was done.  Some older throttles won't connect and
logon to the LocoNet.  Some displayed all elements in the DT300 display and flashed
doing nothing else.  DT400's showed all elements but looked like it didn't have
enough power even though the voltage displayed 13.4 when it was plugged in.
Digitrax has not explained this anomaly but I suspect it has to do with poor power
regulation when plugged in.  I sent my throttles back stating the display flashed and
could not control or insert an address for a locomotive.  When I got them back, they did
NOT have the problem again.

I hope this page was useful in some way.  We want to share our experiences with our
projects so others don't have to go through some of the same labor pains we went through.
Should you have any questions, please ask the Workshop by sending email to:

workshop @ rr-modelers.org (no spaces)