Dear,
Thank you for the answers !
I have a TT-DEC decoder and I will stick to that, no DSD 2010 for me thank you Jean.

For the moment I’m looking at Per his solution.
Cut the detection rail into 3 parts and with diodes bring 2 sensors over 1 wire.
But these 2 sensors are not what Rocail needs.
Rocrail needs “Enter” and “In” sensors.

One needs to process these 2 inputs further.
I’m thinking of following:

Call the detection rails as shown in Per pictures D1 & D2 (left or right doesn’t care)
On positive edge of D1 Flag 1 is set
On positive edge of D2 Flag 2 is set

The “Enter” sensor of Rocrail is then: Flag 1 OR Flag 2

The “In” sensor of Rocrail is then given with following equation:
(Flag 1 AND positive edge of D2) OR (Flag 2 AND positive edge of D1)

Flags should be rest with following equation:
(Flag 1 AND negative edge of D2) OR (Flag 2 AND negative edge of D1)

With this method the locomotive will always runs toward the furthest section opposite to entrance side.

I will try this logic with gates or use an Arduino Nano for this… … … any other suggestions?

So far I tested Per setup with 3 short rails and in Rocrail both sensors K1 (D1) and K2 (D2) always came up together whatever side I put some wheels on ?!!!!!!!!!?

I have to say that I don’t use relays but an optocoupler to bring the sensors into an Arduino Mega DCC++ BaseStation.
The diodes “next to the turntable” in Per drawings are the input LED’s of the optocoupler.

I mentioned spikes on the signal after the diodes on the bridge, so I had to put a LP filter to remove them from the signal.
Now I have one or the other detection in the Arduino, no problem, but I need the logic to “translate” these 2 detections into the correct Rocrail signals.


Last question: How to dismantle the TT without breaking anything so that it can be reassembled correctly after modification?

Best regards
Alain

Hello Jean,
Please check the schematic of Per in post #12 on page 1
Divided the detection rail of the TT bridge in 3 pieces, I think to leave 1 cm at each end.
That way the locs will always run toward that last cm.
Ok, it’s not in the middle as, I think, it was in reality but lots of other things aren’t ok too in model railway and we have to live with it.
I tested this setup with 3 pieces of rail first and have working detection in Rocrail.
BUT, like I said in previous post, these signals K1 and K2 from Per drawings aren’t correct for “Enter” & “In” sensors in Rocrail
So I ordered an Arduino nano to process these 2 signals so that Rocrail can work with them.
Thank you for the procedure to “open” the TT.
To be continued… … …
Amicalement
Alain



The resistor of the LP filter is not 1k5 but 1k2!

I would use the short (1cm) length on the way in, if that is free and the track coming onto the TT is also free, then stop.
(Instead of waiting to get to the far side short piece.)

In fact, I would electrically connect the two short pieces together since you only have to know one edge in any operation.

The sequence of a loco travelling onto the TT could be:

Start with loco on feeder track. feeder track detection ON, TT detection off
loco moves onto TT #1 feeder track detection ON, TT detection ON
loco moves onto TT #2 feeder track detection off, TT detection ON
loco arrives in 'center' of TT. feeder track detection off, TT detection off
STOP loco

This approach lets one combine a single electrical connection on the bridge with the feeder tracks.

sounds like nice progress.

The real test is with different locos that have different lengths and different speeds!

I am weary of using a time calculation as it is not a positive feedback. If the loco does not travel at a constant speed, or gets stuck, or the layout loses power (Eg because of short elsewhere) then your time calculation will be inaccurate.