DCC newbie - Advice on point control and signal automation

[Ch4lkst3r]

Hi,

 

I'm about to come back to railway modelling after many years away.  I've still got all my old DC stock etc. but am wanting to catch up with the modern world and go DCC as it saves on all the old wiring and switches for isolating sections etc. 

 

I've been having a look about on the web and think I understand most things now but I'm wanting to partially automate the signalling so that they will go back to red once a train has passed as in real life.  I'm planning on a double loop as the basis and as the train goes round I want the aspects to change accordingly.  I'm thinking of going down the Digitrax route as the BDL168 will monitor 16 blocks and seems simple enough to wire up and then connect this to JMRI to run the signalling.  Signals will probably be CR Signals with Signalist SC1 boards to control.  There will be points leading off this loop protected by signals with "feathers" to indicate the diverging route which will also be DCC controlled.

 

Here come the questions part:

 

1. If I'm automating the signals to some degree block detection will show where the train is but how does JMRI now the point position when the layout is started?

2. If I use the handheld controller to move a point how will JMRI now that it has been moved.  Does it monitor the DCC bus and pick up on the request?

3. Any recommendation on point motor/accessory decoder combinations?

Thanks for whatever advice you can give me.  I'm sure more questions will follow!

 

Iain

[Nigelcliffe]

I've been having a look about on the web and think I understand most things now but I'm wanting to partially automate the signalling so that they will go back to red once a train has passed as in real life.  I'm planning on a double loop as the basis and as the train goes round I want the aspects to change accordingly.  I'm thinking of going down the Digitrax route as the BDL168 will monitor 16 blocks and seems simple enough to wire up and then connect this to JMRI to run the signalling.  Signals will probably be CR Signals with Signalist SC1 boards to control.  There will be points leading off this loop protected by signals with "feathers" to indicate the diverging route which will also be DCC controlled.

 

Here come the questions part:

 

1. If I'm automating the signals to some degree block detection will show where the train is but how does JMRI now the point position when the layout is started?

In general it doesn't, so you need a command to tell everything to move to the start positions. BUT, because you're heading down the LocoNet route, if you pick your accessory devices wisely, then they can communicate via LocoNet, and thus tell the computer their current position on system startup. For modest layouts, just having a "start of day" command to set the start position is simple and effective.

 

2. If I use the handheld controller to move a point how will JMRI now that it has been moved.  Does it monitor the DCC bus and pick up on the request?

For some systems yes, for some no. For a LocoNet based system the answer is yes, JMRI monitors the commands sent by the system. (Its not monitoring the DCC bus, that's downstream of the command station, and thus not actually visible to the computer ).

 

 

3. Any recommendation on point motor/accessory decoder combinations?

Thanks for whatever advice you can give me.  I'm sure more questions will follow!

Given where you are heading with LocoNet based stuff, look at the ready-to-use products from CML Electronics, or DIY solutions from Hans de Loof.

 

With a LocoNet based system, it can be advantageous to control all devices from the LocoNet, not through accessory instructions to the DCC bus (or track). That's not to say that normal accessory decoders won't work, but there are advantages to the bi-directional nature of LocoNet.

 

 

 

 

For what its worth, I monitor track using a Hans de Loof "LocoIO" with current sensors from MERG DTC8 kits. This works out a lot cheaper than a BDL168, but it does assume you're into assembling electronics devices.

 

 

- Nigel

[Phil S]

Other options to consider:

An NCE Packet Reader is a device/Module from NCE which monitors the DCC track sugnal ... you could then write your own software to monitor the track commands ... this would give you ALL active locos, their speeds and Function states, and everytime an Accessory is operated.

An alternative version is available in kit form through Opendcc.de

 

'Without DCC' (Independant of DCC/analogue) you can get a signal to automatically revert to Red after a preset time with a simple monostable timer: This is, for example, an inbuilt feature of the HECTOR IR detector module available as a kit to MERG members, or a wider range of automation with ready-built modules from Heathcote.

 

Given a detection, the next stage required for automation, is to get it back to the controlling device though a feedback bus or network.

 

But once you decide to use DCC, the option really reverts to Computer software of your choice... and looking for an inbuilt function to trigger an action (accessory change such as signal back to red) when triggered by some other action - either timed off the intial change, or better still, off train detection with the related train having entered the next section and a track occupation detector.  

 

I only have the 'bundled' Rocomotion version of Freiburg's commerical RR&Co - but the 'paid for' versions include that type of trigger event and conditional actions of your choice ...which can be as complex as you wish (including timetabled running).

 

As an 'early adopter' of DCC, LGB (G Scale) also prioduced track-event-triggered-modules which 'issued a command' just as if they had been entered by hand into another controller ... this allowed automatic point changing on reverse loops, and signal automation etc.   I havn't seen these offered for some years.

 

Expressnet bus controllers are told of other controllers actions ... and SOME of the available software will show, simultaneously on the screen, the speed settings of as nay locos as you wish to display.   Eg Rocomotion /RR&Co.    JMRI and /or Rocrail might optionally show the speed and direction data of locos being controlled by physical handsets (One does, and I think I have seen an option for it in the other ??)

 

If you don't have motorised points at present, this would be a good time to look at the SERVO control options now increasingly available ... these avoid MANY of the DISAdvantages of Solenoids, and give the advantes of slow motion drives, whilst being much smaller and easier to set up. Examples are again MERG kits for members, and MinxMicrodrives.com

 

Fundamentally, whenever 'automation' is required in a layout, this means a comprehensive set of train-detectors so that the software can folow a train everywhere (except, perhaps local sidings).  This CAN mean re-dividing the track into electrical sections for each (current detection of loco motor/lighting), OR magnetically operated switches (Reed or Hall effect switche in the track, Magnets on locos) OR optical detection (reflective or beam-break), ... but none of these provide ABSOLUTE identification such as that from RFid tags and readers .... for which the cost escalates!!

 

THEN the information has to 'get back to' the central controlling device ... this is where your choice of Feedback Bus comes in ... eg Lenz, Roco, Loconet, and each requires a MODULE to collect the feedback inputs (usually 8 at a time, but obviously 16 with the Loconet unit mentioned.

Even if you do not use it, if you can wait 'a little longer' until the promised Hornby System is released .- they promise this will  do the sort of thing you want, and presumably economically!  Similalrly Roco have just released sets including RFid aimed at children with Smartphones which they use to drive their trains.

[Ch4lkst3r]

Thanks both for your replies. I have looked at servos for point motors but how do you go about frog polarity switching? Anything I can find to do it with servos seems to be expensive

[chaz]

Thanks both for your replies. I have looked at servos for point motors but how do you go about frog polarity switching? Anything I can find to do it with servos seems to be expensive

 

When I used servos to switch points I wired the to a DPDT switch. One pole was wired to switch the servo driver, the other switched the polarity of the crossing. If you plan to operate your servos from the DCC it should be possible to control a relay simultaneously with the servo. If there is a wire that runs from a DCC decoder to a servo driver this gives you access to a signal which you can use to switch a relay, either directly or through a small relay driver.

 

Chaz

[bigal10]

For me, I find servos the least expensive, and (so far) a very reliable option, - infinitely adjustable, quiet, and very strong.

 

And to answer your question re: frog polarity switching, I use ECoS as the controller, with SwitchPilot Servo as the accessory decoder, with SwitchPilot Extension to do the frog switching.

 

OK, I know ESU's products seem expensive at first, but you've already showed an interest in automation, and for "DCC Newbie" a very adventurous layout!

The combination of SWP Servo + Extension for 4 outputs is no more expensive than many other solutions out there.

 

Good Luck!

 

Alan.

[Phil S]

The MinxMicrodrive solution, from their adverts,/web pages, includes frog polarity switching as well as automatic alignment, and error reporting for when the point movement is blocked - the latter is certainly an advantage when used in the garden!! - I habitually operate the garden points 3 times for each point change, so as to hear they are moving correctly, and a twig or catkin has not fallen into the gap ( many of our points are below a willow tree ).

The Bachmann/ESU Switchpilot, which can be used as the dcc accessory decoder to operate eg the MERG Servo4 switch module, can equally have relays added to it, to provide 'integrated' polarity switching.

 

Yes, solutions all cost money .. it is up to you to decide where it is best spent: I included mention of MERG who offer kits to their members as a 'low cost' route if you are prepared to do a little simple soldering. Otherwise the ready-built Heathcote Servo module can offer frog switching I believe.

I assume that you are using Peco® , Tillig or perhaps handbuilt points... or you wouldn't need to provide separate switching of the frog...

[Nigelcliffe]

Thanks both for your replies. I have looked at servos for point motors but how do you go about frog polarity switching? Anything I can find to do it with servos seems to be expensive

Crossing switching with servos is usually one of three methods: a separate switched output on the device controlling the turnout (eg. within the accessory device), a microswitch which is moved by the mechanical movement of the servo drive, or a short circuit correction device such as a Frog Juicer. I'd advise against the last option as expensive and poor engineering design.

 

The cheapest switch is a microswitch, and there are arrangements which are reliable. The trick is to make the servo arm move a decent distance, and then take out the excess movement with the arrangement of control wires, spring loops, etc.. Thus you're not trying to make the servo move a nats-whisker and thus prone to the tiniest movement (temperature) altering the throw or workings of the switch.

 

Servos can be cheap at the DIY end, I use a Hans de Loof "LocoServo" board. They work out at under £20 to build and control eight Servos from LocoNet instructions, but I'm only buying PCBs from HDL. An Arduino DIY decoder which takes DCC track signals for Servos was recently published which is probably even cheaper, and I'd expect its not that hard to convert to working from LocoNet instructions. There are also various kit solutions from MERG which can be cheap to build.

 

Many commercial systems for servos are expensive, and can work out as more expensive than slow action stall motors (eg. Tortoise, Cobalt, etc).

 

 

- Nigel

[Suzie]

Controlling your points with servos should be the cheapest way of motorising your points and you can use the Signalist SC2 which drives servos and includes built in frog switching. JMRI should keep track of the point position OK even if you operate your points from your controller, and since you will need feedback from the block occupancy detectors (BDL168 or MERG DTC etc.) it should be quite easy to add feedback of the point positions too so that JMRI knows definitively what the point position is. You should be able to use an output of the BDL168 with a small load on it connected to one of the point blades for definitive point position detection if you are keen.

 

JMRI has the best support for UK signalling with feathers etc. out of the popular applications so will be a good choice.

[Ch4lkst3r]

Thanks all for your replies.  I'm considering getting Signalist SC2 boards (obviously with servos) to operate the points (there are a number of crossovers on the plan so I can double up the servos to keep costs down).  As the frogs polarity will be switched via the SC2 are there any mods required for the points (I'm planning on using Code 55 points)?  I've searched and can't seem to find a definitive answer.  Some people seem to say to cut the switch blades from the frog whereas others say not to bother.  I'm assuming that the SC2 will change polarity at the middle of the throw so that there won't be contact between stock rail and blade at the same time.

 

Iain

[Adrian Wintle]

Another option for servos is the Digikeijs/Digirails Servo decoder, but it needs additional components to convert the discrete outputs for frog switching.

Decoder: http://www.digikeijs.com/complete-set-including-1x-servo-decoder-4x-mini-servo-and-4x-50cm-extension-cable.html

Additional bits: http://www.digikeijs.com/dr4102-points-crossing-interface.html

 

Adrian

[Suzie]

You will need to separate the frog from the switch rails when using the SC2 which is just a couple of cuts with the razor saw or a slitting disc (you might like to fill the gaps too). There is no dead band (which makes the SC2 ideal for switching reverse loops) so it will be important to isolate the frog. You will need to attach droppers to the switch rails or connect them to the stock rails and that should ensure reliable operation.

[tyneside emu]

there is an excellent video on youtube by everard junction on creating automatic signals on a layout.

 

[shibushe]

Iain. For what its worth, and I like to keep things simple. I use Heathcote Infra red modules to auto the signal to Red once the train triggers it, you can also time the amount for when it goes back to Yellow & Green.

I also use TT 300 Traintronics DCC Point motors, these I have wired using the spare terminals to control  2 aspect signals. ( No resistor Reqd ). If you want to know the wiring let me know.

 

Another simple control of signals of  I use is, Traintech Signals. These have the advantage of having its decoder built in and as the instructions say,

One touch on the program pads and you can set the signal which ever way the point says clear or not.

I have a number of these.

They come with legs just like the Hornby train set, slip under the rails. Not very reliable.

Me I cut them off and solder two wires direct to the Power Bus, Looks more realistic.

 

Traintronics also do a module to control a signal that has a Feather. Regards.