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Traincontroller 36: Block Occupancy with Momentary Sensors

The block ‘occupied’ status and the corresponding highlight colour only appears as long as the block occupancy sensor is triggered. When working with momentary sensors, like I do with reed switches and magnets, the occupied status flickers as many times as the sensor triggers. Just because one reed often switches two times when a magnet passes over it and also bacause I have multiple magnets under my trains, like on the last wagon, used for driving backwards.

Page 138 of the user manual warns against potential problems when sensors are triggered multiple times by the same train. Although with me TC never got confused and traffic flow was error free, the messages window showed warnings of sensors being triggered when not expected.

Well … I can’t avoid multiple triggers with my sensors … but there are ways to trigger the block occupancy indicator just once, like is advised. This is done by not using the sensor directly inside the block, but by using a Flagman in the block.

On page 292 of the manual a method is described using 2 detectors and a Flagman with its memory on ‘toggle’. This method won’t work for me, since I have only one sensor per block! Also my sensors are triggered more than once, which means this flagman will get toggled multiple times. This is not going to work reliably, I need to find another solution.

What I did is to use switches (one for every block, two for every 2-directional block) on the switchboard as an intermediate ‘memoty’. It is switched on by the sensor, which is now an ‘external’ sensor, it does not reside inside the block anymore. A Flagman is used inside the block, it is triggered by the switch and this Flagman now determines the ‘occupied’ status.

The advantages are:
– The switch is switched on only once, no matter how often the sensor is triggered
– the flagman therefore is triggered only once … absolutely no more multiple occupancy triggers
– the switch can be put off with any occurrence which we can choose ourselves. I chose to do it when the train reaches the stop marker of the block, that way I also can see if a train is driving (occupied is on) or stands still (occupied is off).

Combined with the block release Rule put on ‘Smart or upon Entry’ this gives nice early release of blocks and a nice flow of trains on the layout, see next video nr. 37 for more on this.



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10 thoughts on “Traincontroller 36: Block Occupancy with Momentary Sensors

  1. Will this not work with the contacts inside the block ?


    Posted by Alan | April 5, 2018, 19:51
    • I’m not sure I understand what you mean?


      Posted by RudyB | April 6, 2018, 08:37
      • Hi Rudy
        I have my magnetic switch contacts as part
        of the block, as per one of your earlier videos
        You now show contacts outside of the block
        I assume this doesn’t have to be physically
        outside, but do I have to remove the contacts
        from the block properties/reconfigure them
        Hope that makes more sense


        Posted by Alan | April 6, 2018, 11:52
      • Ahh, I see. No … no need to do any of this. Keep your sensors inside the block. The ‘external sensors’ are merely a way to show them om your switchboard, but there is no real need to do that. It even can make life difficult when you want to drive in demo mode … if you don’t need to do it, I simply wouldn’t.


        Posted by RudyB | April 6, 2018, 13:20
  2. Thanks a lot for your great video’s, I made it to the point where I use reed switches with flagman logic for my track. But if I use these I can’t use the simulator function of TC not so good anymore, I need to manually occupy the next section 😦 Is there a way to use the simulator with the flagman logic as you explain in your video ?


    Posted by Alco Post | November 6, 2016, 23:08
    • Unfortunately not. The simulator only works when you use block nternal sensors. As soon as you bring the sensors ‘outside’ the sim needs the manual input of the sensors being activated. It is a trade off, if you like to be able to use the sim, internal sensors are a must.


      Posted by RudyB | November 6, 2016, 23:33
  3. Hello Ruud,

    First off, thank you for taking your time creating and sharing those tutorials, they’re very helpful. Can’t wait for the next one to come online!

    My layout is to be build yet, but I have a question about this video. I’ll have to deal with the warning in the manual about momentary switching too most likely, since I’ll be using ground detection via Marklin contact tracks, so every time a wheel passes the contact point the indicator symbol will blink like crazy.

    What would be the best solution for that scenario? Can I use your approach as outlined in the video or should I need something totally different?

    Thanks in advance and please keep them coming!

    PS: ben je nu vaste gebruiker van TC gold? De demotijd is nu wel om toch? 😉




    Posted by Erik | February 27, 2016, 14:26
    • I’m not familiar with the Marklin detection system, but if there is a chance the sensor triggers multiple times with one and the same train, the method as shown in the video will take care that everything goes well. Although I found that even without using this, multiple triggers had never caused problems on my layout, this just makes it safer, probably.


      Posted by RudyB | February 27, 2016, 15:02
      • Well, it does not differ from your way of detecting in that there will be more trigger pulses in my case, since every wheel acts as a switch to provide a ground pulse. If you have only one or two magnets per train like in your case, changes are that’s not going to be too much of a problem, like you noticed. In my case it probably will upset the entire automatic train control, as mentioned in the manual.

        Thanks for posting this and for your answer.


        Posted by Erik | February 27, 2016, 16:28

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