Many thanks for the informative reply Simon. I certainly see where you are coming from. and I could not agree more about having nothing below the baseboard - on John's layout, there are cupboards under there as everything is mounted on the basboard fronts, including the servos which then drive the points via over-baseboard wire-in-tube whilst the signals plug-in from above. But my point was that the final connection to the servo is independent of the means of transmission from the frame - at some point you have one wire per lever/one wire per servo! Of course I over simplified how John makes the actual servo connections on Leeds - he uses the MERG controllers via a local relay - it is these which are hardwired to the switches via the D leads. A complication is that in addition to the "proper" controls, an over-ride allows the points to be worked from manual switches allowing John to work the layout when none of the rest of us are there!
Having built and
fully interlocked four quite large installations for Leeds, (each of them bigger than most people's layouts!) using mechanical, relay and software approaches, I am getting a pretty good idea of the upsides and downsides of each. But if there is one thing I have learned from my involvement with the Leeds project, it is that both problems and solutions tend to be rather special for such a complex situation and things which are fundamental to us might be irrelevant to others.
Regarding interlocking in Arduinos, I use a large struct (though if you know enough about C++ an object might be better) to hold all the data which is created in an XL spreadsheet (to be human readable) and then copied and pasted into the code. The same approach is used for mapping all the I/O connection tables, LED function maps. Push button IDs etc. - the
only thing "hard coded" is the logic which is universal and therefore transportable to any layout - so the code contains no "magic numbers" of any kind.
I would be happy to post some code snippets if you (or others) would be interested but since no one asked in response to my Leeds post, I assume no one is bothered.
<on> rant mode
I had a look at the PASSIM project - without wishing to be disrespectful, what a *^*%$ load of cr*p. No wonder there seems to have been no update in a while. I found it totally frustrating: these people do not know the first thing about either signalling or interlocking and have not troubled themselves to learn about it. Worse, they imply no one has ever previously signalled or locked a model railway correctly - I beg to differ and so would many of my modelling friends; one of whom wrote about his interlocked frame in MRJ 35 years ago and has exhibited with it over 50 times since! To PASSIM I say why not start by understanding the principles which have been developed by the real thing over 200 years? There is no problem we face on a model which has not already been solved many times over and it has never been easier to research such things. For my part, I went in my first mechanical signal box 58 years ago, my first panel box 2 years later. And at the age of 14, I spent my Sunday afternoons working a box on an electrified main line (12 trains per hour) whilst the signalman washed his car outside! I built my first interlocked lever frame 54 years ago - and a poor thing it was - and so I reckon to know a bit about the job by now; yet, every new project, every day; I learn more - and
never by re-inventing wheels! (my mechanical locking is pinched from the GW!)
If the PASSIM people want to see mechincal locking simulated in Windows, they could look at my own simulations - including 131 levers at Exeter West and the busiest frame I have ever seen - with 94 working levers - at Crow Nest Junction ...
Mechanical Signalbox Simulations for Windows
<off> rant mode
Looking forward to further developments...
