Control Systems
Introduction
This section describes how my layout operates using the Digital Control Command (DCC) protocol.
It’s information that is most likely going to be of interest to people considering taking up the hobby or converting their layout to DCC operations via a computer.
DCC Principles
DCC allows you to run any number of trains on the same section of track at any speed in either direction. It also allows you to control other train functions like sound and lights, and to control
other layout features like points and signals.
This is unlike traditional analog layouts (also unknown as direct current or DC layouts), where all the trains on the same section of track run at the same speed in the same direction.
DCC works by the controller (or computer) sending packets of digital information to the track. It does this by switching the current on and off at a very fast rate to achieve a binary signal. Each DCC train and track accessory has a decoder chip with its own address. Pulse-Width-Modulation (PWM) is used to even out power to the motor improving control, particularly at slow speeds. When a decoder sees a message intended for its address, the chip controls that action e.g. train number 0925 go forward at speed 70.
In practice, this makes wiring a DCC track very simple. You just need to ensure that the same signal from your controller goes everywhere whilst taking care not to get your wires crossed and cause a short.
Decoders are expensive. But I think it’s worth it as DCC offers the potential for huge operational and functional advantages over DC. I’d recommend it to anyone starting out in the hobby or wanting an automated layout. However, it’s not for everyone and many long-term hobbyists prefer DC systems over DCC, partly because the cost of converting an existing large DC fleet and track is so high.
Original Control Plan
My original intention was to operate my layout manually and keep the costs down. To that end, I initially operated the trains using my Bachmann EZ Command controller from my 1st layout starter set.
I decided not to use DCC for the points operation but built a simple box of switches to control the points.
The points are changed using a mixture of Peco PL-10E and Gaugemaster Seep motors powered by an old laptop charger via a Capacitor Discharge Unit (CDU). A similar setup to that used by many DC layouts.
Despite my EZ controller’s limited functionality and power, this combination of controls worked fine when operating a single train on the track. Technically, it could also run 3 trains at the same time and running loops was straightforward. However, any muti-train shunting maneuvers or route variations required high concentration to avoid collisions, and to ensure points were left in correct position so as to avoid derailments. Needless to say, I was not always successful, and an upgrade was on the cards.
Computer Control System - original
configuration
I tried demo versions of several control systems including the free Java based JMRI. Eventually, I choose Train Controller Bronze by Freiwald Software because of the quality of its display, ease of use and rich functionality even in this entry level version. I’ve found it to be extremely robust and do all the things I want and more! The software is one of the more expensive programs on the market, but I think well worth it.
For the computer interface I selected a Digikeijs DR5000 linked to a Digikeijs DR4088LN current sensor via Loconet. Again, not the cheapest setup, but after reading various reviews and speaking to hobbyists at shows, this came across as being highly reliable, well supported and with good expandability options. The current sensors identify when a train is drawing current in a particular block of track. This information is sent back to the computer software. In this way, the computer knows the location of all the trains and can automatically control routes, set points, and delay trains to stop collisions.
My points decoders are mainly DCC Concepts ADS-8fx operating from the DR5000 track power. These work well when set up correctly, but I found any wiring mistakes or shorts can easily bust a channel – so take care.
The software does not require any significant processing power, and I already had an old no-longer-used PC suitable for the job.
Installing this system required a significant amount of track rewiring. Each block in the system needs to be electric isolated from the rest of the track with an individual feed from a DR4088LN channel. This required cutting the track in place with a Dremel, making good the gap with plastic (to avoid a bump), then soldering new cables to these sections.
Upgraded Computer Interfaces and wiring
Initially I used printer cables to connect the interface board to the track. It worked, but I realised these cables aren’t designed for this and risked overheating. So these have now been replaced by thicker 12-core cables.
I also decided to add an extra current sensor, this time a DR4088 which links to the original DR4088LN via the S88N ports. This required another round of under-table track rewiring and track isolations.
Installing the extra sensor has given significant improvements to routing options and to the controllability. Extra blocks on the bends allows better access to the cul-de-sac sidings on both the main board and fiddle yard. Each train slows down at a different rate and will stop in a different place. So placing 2 sensors in station and siding blocks allows a slow-down sub-section and stop—sub-section rather than trying to combine these functions with one sensor in a block. Different trains still stop in slightly different places, but it’s a big improvement and I have trains that over-shoot.
Train Controller Bronze Computer System
The Train Controller Software provides completely automated control of my layout and allows me to program any sequence of train moves I like. For example, one of my simpler routes is to send a train from the Fiddle Yard to “Station P1”. Let it wait there for 30 seconds, then change the signal to “Go” and set the train off to loop back to the trains original position in the Fiddle Yard. Then repeat this sequence after 4 minutes. I’ve also programmed much more complex routes to move trains between the sidings.
The software checks the planned route is clear before and changing any points and starting a train off. If the route is blocked by another train, it will wait and try again shortly. It will also stop the train en-route if it becomes blocked. For example, the train above might pause on the bend at “B29” if “Station P1” is still occupied.
In practice, this means I can have 5 or 6 trains all moving at the same time and crossing over each other with no fear of collisions or points derailments.
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