Entry posted by GWMark
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It has been a while since I managed to do much (anything) to the little shunting puzzle, my problem has been that the layout had to go up into the loft in order to free the spare room for a visitor and has not made it down since. The problem being it is a big hassle to get it out of the loft to spend an hour working on it and then put it away again. Given the current weather conditions, and the amount of juke currently residing in the loft, the prospect of venturing upwards and doing work in the loft is also not very appealing. I was having the discussion yesterday when I said "I can tell you how long it is, I will look at my blog". It was then that I realised I had failed to document the last bit of progress I made, so in an effort to reawaken the enthusiasm I thought I would "back fill" the story.
Soem years ago I started dabbling with RFID for train detection, this result in the production of a MERG RFID reader kit and has found use on a club layout. I wanted to also employ RFID on my little shunting puzzle, mostly because I wanted to use this layout as a testbed for ideas, but also because I thought it would be fun. The big question was how to link it into the control system, I didn't want something that just triggered slide displays like I had done before, I wanted to have it integrated. This layout uses the MERG CBus system for control, all the accessories, the DCC command station and the throttles are connected to the single CBus, so it seemed logical to connect the RFID to this as well. So the first task was to build an interface between the RFID reader and the CBus - those members of MERG that are interested can see how this was doen in the MERG Winter 2012 Journal. This gave me the ability to send a message to every device on the layout whenever a train passed over the reader, know the question was what to do with it.
The layout currently has no dedicated control panel, instead it uses JMRI running on a laptop display a mimic diagram and control the points. The laptop has a connection to the CBus in order to allow this, so therefore the laptop and JMRI is able to receive the messages from the RFID reader. So my next step was to add functionality to JMRI so that it could understand the messages received from the RFID. Fortunately JMRI has the ability to have something called "Reporters", these are devices that report back train information to the software, they are designed for system like Railcom in DCC that can send train identification from block occupancy detectors. So I created a new one of these reporters to understand my new CBus message for an RFID tag read. The reporter allows a message to be placed on the control panel window when a report is received, this message can be tailored to contain any text you require for a given train identity. Since the layout also has block detection, once a train is detected using the Reporting, as the train moves from block to block, the report can follow it around the layout.
The upshot of all this is that I now have an RFID reader on the single line that feeds into the sidings of the layout, as a train passes the reader a string is displayed that identifies the train. When it moves into the adjacent block the message on the screen will move with it, and stay with it as long as it is detected within any monitored block on the layout. When a second train enters it is also read and can be tracked in the same way. As long as both trains are not is the same block they will be tracked independently of each other. So I now have a mimic diagram that shows me not just what block are occupied but also the identity of the train in that block - just like the real railway does these days.
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