you've gotten this far, good for you. You must be really
Operations Control Centre (AOCC)
explained earlier, automatic train control is governed by
the Automated Operations Control Centre
and the Track Occupancy Status system.
practice, this means that a Windows computer with a DCC
interface runs JMRI which in turn runs a considerable number
of scripts, each of which is customized for a particular
purpose in the operation of the layout.
The scripts are written in JMRI/Jython, an adaptation of
the popular computer programming language Python. Jython
runs under Java and most of the rules of Python apply but
Jython supplies some critical routines to interface the
language to one of several DCC products.
order to run trains automatically, several systems are required
in addition to the conventional DCC components. These are
all integrated under the AOCC which, simply put, is a set
of master scripts which monitor layout operation and run
other scripts as required.
Occupancy Status (TOS) system
system is a fundamental component of the AOCC and is a background
system against which most other systems operate.
Track Occupancy Status system depends on detecting when
a train passes a particular location on the layout. When
this happens, a DCC sensor is activated and a message is
transmitted over loconet. This message can then be interpreted
by other scripts and appropriate actions taken.
layout is divided into "locations" and sometimes
"sub-locations". Each "location" consists
of one or more detectors. Each detector is made up of several
(typically 3 or 4) magnetic reed switches a small distance
apart on a track at a given location. These devices are
wired in parallel and connected through a resistor (10K
ohms) to a Digitrax BDL168 block detector.
detector location is shorter than a conventional block which
is typically a length of track a few feet or more long.
On the other hand, a detector location can be thought of
as more of a point location on layout. In some ways, that
can be an advantage in that the location of a train is known
precisely, rather than only knowing that the train is somewhere
in a block.
example, if a train is traveling in a given direction and
reaches a detector location, the system might wait a certain
number of seconds and then sound the horn for a crossing.
This, of course, depends on the distance the detector is
from the ideal point where the horn should be sounded, the
speed of the train, and possibly other factors as well.
The AOCC keeps track of everything and it works fine. When
new trains are added to the layout, their speed might have
to be fine-tuned a bit for optimal performance.
components are illustrated below:
Magnetic Reed Switch (normally open)
Sensor location on main lines
a detector car passes over a detection location, a BDL168
(Digitrax block detector) acts as if a locomotive or a car
with a resistive wheelset is detected in a conventional
block detection system and sends out a message on Loconet
that that block is in use. That is, a sensor is reported
as being Active.
Detector car - located at head end of train just behind
messages generated by the activation of a detection location/block
occupancy indication are monitored by computer scripts running
under JMRI and any required action can then be taken. A
typical action might be to wait for a given sensor to become
active (indicating that a train is at that location) and
then throw a turnout, sound the whistle or horn, change
a signal aspect, wait a given number of seconds, or any
one of a number of other actions.
the script accurately keeps track of each train (by engine
number), its direction of travel, where it was last detected,
its speed and other factors, it can report that the given
train is now at the newly detected location and instigate
the updating of tables, computer logs, track diagrams and
train locations among other things.
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details on any of the above can, of course, be obtained
by contacting RHJ