For exhibiting 'Camford Junction' at our show in Basingstoke back in March, I had cobbled together various modules purchased on eBay, controlled by an Arduino, all screwed to a piece of wood and joined up with a bird's nest of wires. This provided the five analogue DC controllers to drive the trains on the layout. By pretending to be a Merg DCC Control Station (CANCMD) it allowed Merg hand-held throttles (CANCAB) to be used to control the trains. It also meant that JMRI, running on a laptop, could also provide on-screen throttles, and by hooking up a WiFi access point, Android and iPhone throttle apps could also be used to drive the analogue DC trains.
Having performed faultlessly all weekend, I had to tidy it all up,
and put it into a proper case for protection. This has taken longer than
the original build.
I have also been thinking about the problem of failures and
rectification of faults during an exhibition. With a club layout, there
will always be some concerns amongst the membership about the
reliability of new technology. For Camford Junction, I have tried to
make fault rectification as simple as possible, by standardising and
separating things. The layout is powered by several identical
laptop-style 12VDC power adapters. We will have a spare one that can be
used to replace any one of these in the event of a failure. So far, I
have used only two types of Merg CBus modules, the CANSERVO8 module to
control up to 8 point servos, and the CANACC8 module (modified for 12V
DC power) to operate a standard 8-relay module widely available from
eBay, to switch track sections between controllers. We will carry a
spare for each module, which can be quickly swapped if required. It will
be necessary to plug in the laptop to load the configuration data into
the new module for its new location.
The new control box is a different matter. If one of the other
layout modules fails, it will disable a few points or a few track sections, but
if the control box fails, the whole layout will grind to a halt.
Repairs under exhibition conditions would also take some time. The
simple answer was to build an identical spare. Fortunately, the total
cost of all the modules in the case is reasonably low, but it did
require a lot of drilling holes, crimping, and soldering. The end