Hi

I have a blockage in my understanding of one principal in feeding back train position to the pc. Hopefully more experienced members can explain this process to me thanks. I am just about to embark on using software. I currently use Ecos but dont use the layout mapping so no feedback yet and no seperated sections of the layout. I was always going to use IR and or reeds for software control.

Whilst I understand when using a reed switch to send a (1) signal to the software that the train just passed over the position - then what? How does the software know the train is now in another position such as 500mm further down the track?

As I understand things - the reed is just in one spot - so without putting reeds every few cm's or inches - how does the software track it "continuously"?

(I am wondering if 2 reeds are used as in the old block system - where reed one signals the train has entered the "beginning" of say a 1 metre block and lights up the train icon in that block until the train triggers the second reed switch ?

I would really appreciate some insight into this subject and the principals employed. I could use IR across track methods or isolate 50mm of track by cutting one outside rail in the same way - but its still a short signal to the software and then the train has moved on.

Rgds

Greg

I don't have any experience (yet) with the digital and feedback train layout specifics, and am only speaking from the point of view of an electrical and computer engineer.

Reed switches are effectively 'contact switches' in the feedback system - a part with a magnet passes over them and they briefly close while the magnet passes. This change in switch state is detectable by the feedback system - so it knows something with a magnet just passed this switch.

The control software must knowwhere the switch is, in order to make some reasoning based on that feedback signal.

Electrically isolated track sections are not needed for this, as the reed switch feedback is independent of the track and power.

If you electrically isolate some track parts you can just as well detect that some rail vehicles are in that section - the benefit here is that you will know if anything, be it locomotive or car, is in the section, based on how you set things up. If current draw is used, only the loco would possibly be detected, or current drawing lighted cars. If the conductivity between the two ground rails is detected, any AC (ie conductive axles) cars are detectable. So you can determine if a train has fully left a section to know its clear, not just that the locomotive has passed a given point.

For software control, the ideal situation is to know where exactly a locomotive and all of its cars are located on the layout. You can do that visually but by sensors that is very expensive and complex.

In theory, in the world of digital decoders on locomotives we could get a locomotive broadcasting its presence back to a control system via an electrically isolated section, so if a control system detects there is a locomotive in an isolated block it could issue an identify yourself request, to which the locomotive responds - thus helping the control system conform where the locomotive has just entered. But that cannot be used to give you exact location within a block (without great expense and circuitry). Whether the Märklin system supports such query-feedback I don't know.

So for control systems to work with the simple feedback we have, you as the software control writer make some assumptions.
You have routed a train to a particular section of the layout via setting switches and commanding the locomotive to drive. When the reed or load feedback detects a presence, you assume that the thing that just entered the block is indeed the locomotive you are trying to get to go there. Since you are in theory the only control system for the layout, the chances are very high your assumption is true. By creating rail sections that are of the right length with respect to train lengths, you can know that if a detection takes place at some point, that the head or all of the train must be inside a section, and can set the section it came from to free.

Its all a trade of using the simplest reliable presence detection combined with a layout design that allows making assumptions almost certainly to be true, and using that to turn signal states. One can use signal states to power the track just beyond them, so that a red signal will always have a depowered rail segment past it which would cause red-light runners to come to a stop. Thats added safety, and mimics some real world safety systems results. But thats just supplemental.

There isn't yet the ability to put programmed controllers INTO the locomotives such that the locomotive can detect when it gets to a certain point (by an RFID chip it can detect) and thus stop itself. I can see that coming down the road, but I don't think we are there yet. For now, a processor off track manages it all.

Hi,

To answer your specific question;

By telling the PC software on startup that train A is in block 1 and heading in direction X it will then keep track of the train. I.e when block 2 is being occupied it will assume this is train A and so forth.

The more blocks and the more feedback you have the stronger system you have. However if you have a faulty turnout and there is a mitchmatch between reality and what the computer knows, you will of course head towards trouble and potential collision.... Just like in the real world.

Anyway this is the fundamental difference between CS and PC software. A CS will never know that train A has just passed block 2, it will just initiate the action every time something pass the feedback sensor in block 2.

Railcom+ is a bit different. Here the decoder for individual locomotives will feedback their ID to the track and sensors placed along the track and will then be able to identify what train has actually passed the sensor. It's probably the safest system, but the sensors does require more wiring than e.g. a simple contact track with 1 wire running to a S88 feedback module and not all systems support Railcom.

It would have been nice if Marklin had designed something similar e.g that a signal could functioning as a ID listener and report back to CS. Maybe in the future, as they seems to be heading towards more and more layout automation with the CS.

Brgds Lasse

Hi Greg! Are you using M, K or C tracks?

Peter

Hi Greg,

Railcom is designed for dcc protocols only. Railcom + is the newest system which allows automatically registration of the decoder (similar to the mFx protocol).

MFx decoders are not multi protocol. Some Esu decoders are (can be used on both dcc and mfx).

See also link: http://www.locgeek.com/2...com-plus-what-are-these/

Reed switches are getting mixed reviews. The disadvantages is of course that it will only detect the loco or car that has an magnet while contact tracks or IF sensor will detect as long as something is physically on the sensor. Some users also claim it to be less reliable.

If you have C or K track I would recommend making up your own contact tracks by isolating one of the outer rails.

Brgds Lasse

you may want to read through this too..... http://cabin-layout.blogspot.com/2006/11/computer-control.html

Edited by user 22 April 2017 20:48:35(UTC)  | Reason: url change