Märklin Digital for Dummies ^® Stopping Areas

An important requirement for your computer operated layout could sometimes be to combine (a) Occupied Track Feedback (s88 functionality, as described in the Occupied Track Feedback section) and (b) Stopping Area Control. You control power on/off in Stopping Areas with "k84" decoders, like the Märklin 6084. These decoders can also be used for controlling street and building lights, signals (like the Viessmann 4011 signals I am using) and motors (in my case, the cableway to the mountain top).

What is the combination of Occupied Track Feedback and Stopping Area Control good for? Well, in general, you don't need to include stopping areas in computer operated layouts, as the computer manages commands to the locos to stop and start, with decreased and increased speed etc. All locos have different features in speed etc and the exact location where the loco will stop may vary. A stopping area is an isolated track where you simply control power on/off, as a light switch. This implies that the trains will stop prompt when arriving to such areas (of course, if power is off).

If you let a signal control power on/off, it has to be switched to green whatever direction the train is passing. I am not trying to reach a complete realistic layout, however, I must admit it looks a little bit strange when a signal switches to green as a train arrives in full speed in the opposite direction. Maybe this method is to prefer on double track lines, having one way traffic on each line? Of course, adding extra relays or signals can eliminate this issue, but I would recommend to let the digital system control the braking and stopping of trains instead, see further in the Implementing (Software) section. Here, signals should be used because they look nice and belong to railways. They should not control power, which will save you from considerable wiring.

The stopping area  feature is appreciated in hidden areas of your layout, when you really want to know that a train will stop at a certain position, e.g. according to a meeting point, and you are operating certain trains partly manually.

But why combine (a) Occupied Track Feedback and (b) Stopping Area Control? When a train is standing still at a stopping area, the computer needs to locate the train, to restrict access to the block for other trains. The combination of the (a) and (b) provides this for us. I use this combination in my hidden meeting area on the layout.

Click on the link below to derive an example on how you can use the same track section for both Occupied Track Feedback and Stopping Area Control:

This example use the LDT (yes, that firm again!) SA-DEC-4-MM decoder for Stopping Area Functionality, an alternative for the Märklin 6084 decoder (k84), signals or any relay. 

Digital Spaghetti? RM-GB-8 (left) and SA-DEC-4-MM (right)

In the drawing - and in the picture above - you will also find a 1.5 kOhm resistor (0.25 Watt) included. The resistors I'm using are provided from the local TV service provider and are colored with brown, green and red stripes. (A kind of standard for the "resistance" people, I guess?) If you anyway will buy items e.g. on the Net, the Viessmann product 6836 provides 10 resistors at less than 30 SEK / 3 USD.

The resistor should always be used on stopping areas to bridge the track between the isolated and powered section. This ensures that enough digital track supply voltage is present for the locomotive's decoder memory, but the most important contribution is that it enables the locomotive to consume enough power to provide Occupied Track Feedback via the RM-GB-8 module. Note that if the resistor is broken, it could pass 16 Volt AC to the Stopping Area, even if power should be "off".

With reference to the drawing that combines Occupied Track Feedback and Stopping Area Control, as an alternative you could connect "Abschnitt 1" to the connection 2 (instead of  connection 1) of the RM-GB-8, i.e. the same connection that the SA-DEC-4-MM is using. This enables you to use a longer contact track ("Abschnitt 1" and "Abschnitt 2") which ends with a short track section that you can control with power on/off ("Abschnitt 2"). This could limit the number of contact track connections needed on (the hidden sections of) your layout, however I am not using this feature anymore (as I have invested in further contact track indicators).

In the Contact Track drawing of the Occupied Track Feedback section, you willl find the combination of Occupied Track Feedback and Stopping Area Control in four contact tracks:

The MP2 and MP3 tracks are for one-way traffic only, the MP1 track will manage traffic in both directions. Note that 1a.1 etc. are the addresses for the Occupied Track Feedback modules. As I have reserved the first 40 digital addresses for standard Solenoids, the digital addresses for the stopping areas are set as follows:

You set the addresses of the SA-DEC-4-MM according to the LDT self-learning method.