Sometimes it is necessary for Traincontroller to force a SIGM20 signal to red. This can be where a train needs to take a route that is blocked by other trains; at crossings for example. The SIGM20 doesn't know that Traincontroller has reserved track, so can't take account of it.
The SIGM20 still sets the signal to red/amber/green based in the track ahead. All this change does is to set the signal red for other conditions that haven't yet affected the track ahead, but may do so soon. I suspect that most signals will need this setting eventually, if it is to become safe for a human train driver to drive round the railway.
I've finally added dwarf signals at Eastleigh and Portsmouth container yards. In both cases they control exit from the yard tracks to the main line.
The models were kits, from a Chinese source via ebay. You get a plastic mounding and the LEDs; enough for 10 signals for £8 which was excellent value. Superglue holds the LEDs in. I've arranged the LEDs "back to back" so they only have 2 wires. With one polarity the green LED lights; the other way round the red LED lights.
The signals are controlled by SIGM20 boards as usual. The signal heads are programmed as "2 wire searchlight". Because they have no amber aspect, there is no "next signal" number programmed. For the signals at Eastleigh, the next signal should actually be a virtual (among other things to tell you if one of the 3 possible platforms ahead at Petersfield are occupied). Strictly I should add "signal 257 is red" to the "go red when" conditions.
The original plan had been to make some kind of searchlight signal from a red/green bicolour LED and a plastic block. The mouldings for these signal bodies made that ida daft. I've now ordered some 3 aspect versions for a 4 head signal gantry at Portsmouth.
When I was younger, I wanted my model railway to have signals. But not just signals set by hand: I wanted them set automatically as trains went past, when the track ahead had a point set against it etc. The technology just wasn't there 30 years ago.
When I started again into this - about 10 years ago now - I looked into DCC as a way to control trains and realised that now, all of the information to work out a signal aspect was available on the command bus. The idea of automatic signal control started there, but I has to learn LocoNet and DCC first.
There aren't many signals on the railway yet: but there will be. It's a modern image railway, so there will be colour light signals, set automatically as trains move. When a train passes a signal mast, the signal will go red; when the points in the track ahead aren't set correctly, the signal will go red. CML Electronics' SIGM20 does all this, and more.
The SIGM20 is fundamentally a LocoNet device, rather than a DCC device. All the information to work out the signal aspect is on LocoNet. It knows the positions of the points; it knows what track sections are occupied; it knows what other signals are set to. The SIGM20 hoovers up this information, and works out what each signal should be set to.
This is the definitive list of all of the signals on the railway.
|1||201||Portsmouth platform 1 exit signal|
|1||202||Portsmouth platform 2 exit signal|
|1||203||Portsmouth platform 3 exit signal|
|1||204||Portsmouth platform 4 exit signal|
|1||205||Portsmouth GR1 exit|
|1||206||Portsmouth GR2 exit|
|1||207||Portsmouth spur on entry to Portsmouth|
|1||208||Portsmouth GR3 exit|
|1||209||Virtual at diverging junction in Portsmouth ladder.||Yes|
|1||210||Virtual in Portsmouth loop at diverging junction||Yes|
|2||217||Main line ORANGE signal before Portsmouth loop junction|
|2||218||Portsmouth reverse loop 1 exit signal|
|2||219||Portsmouth reverse loop 2 exit signal|
|2||220||Portsmouth reverse loop 3 exit signal|
|2||221||Main line GREEN at foot of Butser hill|
|2||222||Main line ORANGE at foot of Butser hill|
|2||223||Virtual in Portsmouth approach||Yes|
|2||224||Virtual in Portsmouth approach||Yes|
|2||225||Virtual at diverging junction in Portsmouth ladder.||Yes|
|3||233||Main line ORANGE storage track 4 exit under Eastleigh|
|3||234||Main line ORANGE storage track 3 exit under Eastleigh|
|3||235||Main line GREEN storage track 1 exit under Eastleigh|
|3||236||Main line GREEN storage track 2 exit under Eastleigh|
|3||237||Eastleigh stand 2 exit to main line|
|3||238||Main line GREEN at junction for Petersfield loop|
|3||239||Reverse loop exit to main line at Petersfield Loop|
|3||241||Virtual at diverging junction in Portsmouth loop||Y|
|3||242||Virtual to entry to ORANGE storage roads under Eastleigh||Y|
|4||249||Main line GREEN at junction for Portsmouth spur|
|4||250||Portsmouth spur at entry to GREEN main line|
|4||251||Eastleigh stand 1 exit to main line|
|4||252||Petersfield platform 1 exit|
|4||253||Petersfield platform 5 exit, ORANGE|
|4||254||Petersfield platform 4 exit, ORANGE|
|4||255||Main line ORANGE at diverging junction to Portsmouth spur||Y|
|4||256||Main line ORANGE at diverging junction to Eastleigh||Y|
|4||257||Main line GREEN at diverging junction into Petersfield||Y|
|4||258||Main line GREEN at diverging junction into Petersfield||Y|
|5||265||Petersfield platform 2 exit, GREEN|
|5||266||Petersfield platform 3 exit, GREEN|
|5||267||Fiddle yard ORANGE line 1 exit|
|5||268||Fiddle yard ORANGE line 2 exit|
|5||269||Fiddle yard ORANGE line 3 exit|
|5||270||Fiddle yard ORANGE line 4 exit|
|5||271||Fiddle yard ORANGE line 5 exit|
|5||273||Diverging junction on main line ORANGE at entry to Petersfield||Y|
|5||274||Entry road to Eastleigh, diverging jn at double slip to track 1,2||Y|
|6||281||Fiddle yard GREEN line 1 exit|
|6||282||Fiddle yard GREEN line 2 exit|
|6||283||Fiddle yard GREEN line 3 exit|
|6||284||Fiddle yard GREEN line 4 exit|
|6||285||Fiddle yard GREEN line 5 exit|
|6||286||Diverging junction on main line GREEN into fiddle yard||Y|
|6||287||Diverging junction on main line GREEN into fiddle yard||Y|
|6||288||Diverging junction on main line GREEN into fiddle yard||Y|
|6||289||Diverging junction on main line GREEN into fiddle yard||Y|
|7||297||Main line GREEN at diverging junction to Clanfield|
|7||298||Main line ORANGE at Clanfield junction|
|7||299||Clanfield platform 3 exit|
|7||300||Clanfield platform 2 exit|
|7||301||Clanfield platform 1 exit|
|7||302||Diverging junction on main line ORANGE into fiddle yard||Y|
|7||303||Diverging junction on main line ORANGE into fiddle yard||Y|
|7||304||Diverging junction on main line ORANGE into fiddle yard||Y|
|7||305||Diverging junction on main line ORANGE into fiddle yard||Y|
|7||306||Diverging junction on main line ORANGE into fiddle yard||Y|
|8||313||Orange fiddle yard track 1 centre|
|8||314||Orange fiddle yard track 2 centre|
|8||315||Green fiddle yard track 1 centre|
|8||316||Green fiddle yard track 2 centre|
|8||317||Petersfield reverse loop behind fiddle yard|
SIGM20 serial numbers:
|2||7||panel under Portsmouth|
|3||6||panel under Eastleigh|
|4||5||panel under Eastleigh|
The first section signalled is the fiddle yard. The fiddle yard isn't a scenic section, so the signals don't have to look that part. Instead there are small signals inserted into the baseboard. Small signals made from 3mm red/amber/green LEDs have been assembled using veroboard, and mounted into the baseboard to the left of each track.