Hi Eddie

Thank you for your warm wishes. Merry Christmas to all of you too.
Here is a Rocrail (RR) fan using 3 rails and Märklin from France.

If I mention 3 rails, this is because the point of detection is very important for the point of stopping. In 3 rails, it is the first non-insulated axle while in 2 rails, it is the first voltage-picking axle that counts

With Rocrail, you have a very precise stopping point by using those principles (there may be other solutions and I don't know them all, far from it):
- all locos have a digital decoder with an adjustable inertia simulation (in my case, with Märklin, there is a speed curve that is freely adjusted)
- RR offers the possibility to use 1, 2 or 3 sensors for each block
- among those I use 2 sensors per block (ENTER and IN), sometimes, for bi-directional blocks I use ENTER and IN or ENTER, ENTERSHORTIN and IN) and vice-versa of course for the other direction
- RR offers 4 speed adjustments per loco (V_min, V_mid, V_route and v_max. Lets focus only on V_mid and V_route
- of course not all trains have the same braking / acceleration and the same speed (heavy freight train and superfast trains and a whole spectrum in-between)
- RR, in its normal settings have a train travel at V_route speed between stations. As soon as the ENTER detector is active in front of a red signal, the speed is gently (thanks to the decoder in the loco) reduced to V_mid.
- When the train reaches the IN detector, then the speed is gently moved to zero.
- I use a standard length of 20 cm for the IN detector and the rest of the block length for the ENTER detector.
- I set decel/Accel value for the type of train and then I set the V_mid and V_route to have a precise stop before the signal and a route speed that correspond to the train type
- any train entering a block must have finished its deceleration (down to V_mid) BEFORE entering the IN section.

In 2 rails it may be a little more difficult depending where is the first pick-up wheel to set a precise stop UNLESS you use graphite paint on the insulator of wheels (esp. leading and trailing ones. You must in that case reach a resistance of 5 kOhms per axle.
The reward of all this is that ANY train can no be a shuttle train and still stop at the right place

Just to show my point, here is my 3 rail layout in operation (in cold France, it is winter now )

I hope I answered your question

Cheers
Jean
PS I tried to use BBT but I was not impressed by it so I prefer the method above

Edited by user 24 December 2023 22:10:32(UTC)  | Reason: Not specified

You need to adjust your loco MIN speed settings in Rocrail so that their minimum speed results in the same speed so that they all stop in the same distance.

Ie. for freight locomotives with a slower cruise speed, their MIN speed might be set to 30, while an express locomotive with a faster Cruise speed you need to set the MIN to 15 or 20.
This way when they are both doing MIN speed, they are moving at the same speed.

Hi Jean,

I really love your layout, the locomotives are beautiful too!
I will take your advice and play around with the settings.

Joyeux Noël et bonne années!

Eddie

This is because the Roco locomotive will be configured with a 3 point linear speed table, rather than Marklin locomotives which are always configured with a exponential speed table.
Therefore the Roco takes longer to stop and accelerate at any given speed.
You can re-program the Roco to an exponential speed curve, the same as the marklin.
I have done this myself as well for Roco and Brawa locomotives otherwise they take too long to stop and reach top speed - the exponential table looks and functions better in my opinion, you still get the really nice slow start chuffs without taking forever to start or stop.
I use lokprogrammer for Roco since they were ESU decoders, the Brawa I had to change manually with CV with its DH decoder but it will be different CV than for the ESU decoders.

Yes it is easy to make changes with CS2/CS3.

Looking at page 26, you want to change from a 3 point to a 28 point speed table. This means changing CV29 bit 4 from a 0 to a 1.
So default value is 14, (0000 1110 - this is bit 7 to bit 0, which is 8 + 4 + 2)
This means you want to change CV 29 to value 30 (0001 1110, which is 16 + 8 + 4 + 2)

So with your loco on the programming track, go to CV programming on your CS2/3. Have a look for CV29. If it's not there you can just manually add it, type 29.
First, read the CV which should come back with value 14.
Then enter value 30 and write the CV to the loco.

Done.

Hi everyone,

Just an update, I followed the instruction regarding rhe CVs and then played around with the acceleration / brake delays.

I can now say it works just how I want it. I was. Bit confused since the values work a bit differently to Marklin, I guess it’s the difference in decoders.

Anyway, thanks to everyone here for helping me out. I’ve noted this down for future reference.

Regards,

Eddie

Hi Alain,

Thank you so much, I will check this out.

Since it’s summer here in Australia, I haven’t been working too much on my layout. In my spare time, I have been concentrating on the installation of lighting on some new coaches I have and I’m waiting for a couple of new locomotives as well.

In the next month I will look at this again and do some experimenting. This video will surely be helpful (it will test my language skills, i used to speak Flemish when I was kid but just haven’t used it much).

Many regards from Australia!

Eddie

I am going to start educating myself more on Rocrail's BTT system, just need to finish up some wiring in the yard.

Thank you JohnJean, will do!

Hi
Here is a page to explain BBT (Block-Brake-Timer)
https://wiki.rocrail.net/doku.php?id=loc-bbt-en
The principle is a self-learning program FOR EACH LOCO to send multiple speed commands (standard 10 steps) to re-create inertia simulation.
It is ressource-hungry as a BBT table is needed for each loco, each direction and each block.

Example: I have more than 100 blocks, 28 locos that would mean 100*28*2= 5600 tables (which is crazy)

It was intended as an improvement to old-style decoders (w/o inertia simulation) to obtain a smooth deceleration.
While it still exists and works, on medium to large layouts, it fell out of favour especially with ubiquitous modern decoders.
Why, overload your digital system with plenty of digital commands for ONE loco?
The overload of the digital system results in degraded performance (more time needed to send other commands thus affecting the precision of movement control.

Cheers
Jean

From the Wiki Link that Jean posted - basically, as Jean stated above, the more blocks & locomotives - the higher the demand. I understand now, as I add Blocks & Locomotives that this situation will soon present itself....

Advice
1. Do not set the decelerate decoder CV 4 to zero.
2. enter2in is not supported.
3. The use of Event Timers will not lead to a stable interval; Reset them to zero!
4. Use as less brake steps as possible to reduce communication overhead; 10 steps is default and a good choice.
5. Use at least 28 decoder steps; Better are 128.
6. To get used to this function it is advisable to set a linear speed curve in the decoder.
7. The longer the block, or the distance from the start of braking to in, the more steps and higher CV4 value should be set.
8. BBT needs extra CPU power so disable BBT if its not needed.

Merci beaucoup for sharing your expertise & experience Jean!

Thank you Jean & Martti, your experience & knowledge is always helpful.

Thank you for making this new experience go much smoother.......

Applor,

I believe I have experienced this a couple of times. So tell me if this is correct.

After a locomotive uses BBT for a block and the stopping point is set were the user wants it (1-2 cm in front of the signal). Just change the setting
under locomotive properties/BBT to fixed and it will always use that setting.

Hopefully I have adequately explained this.

Rich S.