Loco CV adjustment

[model-trains]

I am using the following

- iTrain 5 software

- DR5000 Digicentral controller

- DR4088ln Feedback

- DR5013 Reverse Loop

 

I am currently speed testing my locos one by one.

 

The current loco is Bachmann Royal Signals P6 DCC with LokSound 4 sound

 

I am speed testing the locos on a 3 metre length of track, separate to the layout.

Default CV's

CV2  min speed = 3 - during testing changed to 6

CV3 Acceleration rate = 179 - changed to 3 (as sound chip loco)  options for sound these cv's 2,3,4,5

CV4 Deceleration rate = 107 - changed to 3 (as sound chip loco)

CV5 = maximum speed = 50 unchanged

 

Speed Measurement results Forward & Shunt 1-86mph

 

Loco itself capped at 50mph although I reduced this to 48 then 46 for best from sound.

 

The track is clean, the loco wheel are clean, power is only picked up from the 4-6-0 not from the tender, Offsets set accordingly.

 

Everything so far seems reasonable (to me) but running on the Speed Measurement track 3m, to stop within 5cm of the other end is considerably in accurate.

 

The loco is set to run Block 1, 0-25mph, centre block to loco set top speed, 3rd block to brake and stop at the 5cm stop marker.

 

Comments on this welcome guys, but there is another item I think needs to be looked at first, and I am a bit lost on this one.

 

The loco is set to run, the speedo goes up to 25mph, a second or more later the loco sets off, going swiftly up to the maximum speed for the block, 25mph, no gradual speed increase. I have tried CV3 & 4 on 2,3 and 4 setting, 3 seems to be the best, is there other ways round this issue? Are there other CV's that control when a loco should set off without a delay and slowly build up speed?

 

Paul

 

[BoD]

Why have you changed CVs 3 and 4 to 3?

[model-trains]

Hi BoD

 

Many thanks for your response.

 

I have been advised to do this for all loco's with sound, the reason is to allow iTrain to control the loco speed and stopping and not the chip. The loco's have their own method of speed control and stopping in the chip, many se a run on to provide a realistic stop, which can vary the point of stopping for the loco making it harder to stop in the same place every time, even within 1cm.

 

The addresses for best results with iTrain, for CV3 & 4, can be either 2, 3, 4 or 5

 

Paul

 

Edited October 20, 2020 by model-trains

[Nigelcliffe]

This is a sound loco.   I think the following may be happening: 

 

In many sound projects, there is a delay built into the start-off from zero.  The cylinder drains open (big hiss) and various other noises play, before the loco starts to move.  

The software may be accelerating the loco away from zero through several speeds, whilst the sound chip is still clearing the cylinders and the loco is not actually moving.  When the loco starts to move after the delay, the speed its being told is "25mph", so it romps to that almost instantly because acceleration is only "3" (ie. really fast acceleration).  

 

If the above is correct, I can think of four solutions: 

a)  tell the iTrain software about the delay from starting, and have it build that into its actions.   

b ) tell the decoder through CV changes to not carry out the starting delay.   See section 13.2. "Prime mover startup delay"  in the LokSound manual.  

c)  put the acceleration back to how it was originally, and work around that within iTrain.   Those with more experience of iTrain can say if that is remotely sensible.

d)  get your sound provider to produce a new version which doesn't have the delay sounds at start-off.    

 

The first two are likely to have implications for how the sounds play in relation to loco movements.  

 

 

- Nigel

[model-trains]

@Nigelcliffe

 

Many thanks for the details you have provided.

 

My concern with sound loco's is naturally changing to much that the sound will not sync with the changes, which is in agreement with your final statement.

 

Option 'c' does seem the most logical but, the loco decoder has a reaction delay built in, If I don't change anything this RD has to be considered with a further RD for iTrain to achieve the stopping position required. This is a new area for me, like walking in a fog I guess. Not totally understanding the RD to the variables in the sound chip, I am left wondering, how this can affect other items like block length and loco speed. Before asking the question in the forum I have experimented but have ended up with a large RD time.

 

/____Block 3______/_____Block 2_____/_____Block 1_____/ All 3 Blocks are approximately 90cm long

 

Block 1 max 25 mph, Block 2 max speed set for loco, Block 3 max 25mph

 

Inertia simulation for both Acceleration and Braking is built into iTrain for the loco at 200ms and Step size 4 for each

 

When the loco is run under the conditions stated the aim is to stop on the mark 5cm from the end of the end blocks subject to direction of travel. If the loco is short or over runs a further timing is added to the Reaction Delay in ms. Using the locos standard chip settings this can be as high as 1800ms, adding or subtracting from the current figure to compensate for the stopping position can roll up to double this figure, 4000ms Reaction Delay being 4seconds.  This causes a further concern as the loco entering the last block, braking and stopping is less than 4 seconds, so the loco doesn't seem to be controllable where the time to stop in ms, is greater than the actual tie to stop in ms.

 

Model trains, great stress busters, just create, program and play 

 

Which ever way I go, or can hopefully go, there are 3 main issues I think

 

1 - change to many items and the sound won't sync as it should

2 - the delay at the beginning and how to better control it

3 - the dreaded run on at the end when the loco speed as stopped in the speedo, but the train runs on because it has been programmed that way to come to a gradual stop.

 

The issue I find isn't all loco's, I have already programmed some with 2,3,4 or 5 on Cv3 &4.

The issue isn't one type of decoder I have already programmed some LokSound 4 sound decoders.

 

There does seem to be a definite issue with Hornby locos, especially TTS Sound locos. They love to make CV2 and CV5 N/A. I am leaving the Hornby and Hornby TTS until last for this reason.

 

Comments always welcome

 

Kind regards

 

Paul

[model-trains]

I am going to reset to default, except for loco address and try again.

 

Reaction delay timing does concern me when the timing gets high, adding the loco chip delays and additional Reaction Delays to maintain an accurate stopping position within 1cm.

 

Paul

[BoD]

I use Rocrail for computer control.   I did not adjust the various speed settings in the loco because, as Nigel said, it does impact on the synchronisation of running and sounds - which is why I asked my  original question.  All of my deceleration rates and stopping was done by altering parameters within the software itself.   I'm sure that someone who uses iTrain software will tell you if this is a) possible and b) where to find it.  The main disadvantage with this was that it had to be done loco by loco with an element of trial and error.  I don't need it within 1cm either, I'm happy to get it within 2-3 cm.  Good luck in finding a solution.

[model-trains]

@Bod

 

Thanks for your explanation, all help is always appreciated.

 

I am not worried about loco to loco or trial and error, only a satisfactory result in the end. 1cm is a target, every loco is different, as I am finding. 

 

As far as I am aware at this time, there is inertia simulation and step size, for both acceleration and braking, and the Reaction Delay in ms Forward and Backward in iTrain.  CV2 start speed voltage and CV5 maximum speed in the decoder, CV2 and CV5 are N/A in many Hornby locos, especially the TTS ones.

 

Sound makes it more difficult, an area I take carefully, I only have 1 locos but 7 have sound, 3 are TTS Sound, 4 are LokSound4.

 

Thanks again for your comments Bod.

[model-trains]

Ermmm

 

This loco is certainly trying.

 

All CV's set to default, except CV1 for loco. 

 

With sound on or off, the result is that the loco goes 'well past' the stop position. In block 1 the loco gradually picks up speed, the same in Block 2, as soon as it enters Block 3 the speedo decreases and the loco brakes, but runs over massively, both directions.

 

I started with Reaction delay of 2000ms, raising in 500ms steps, after 3500-4000 (4 seconds) no difference.

 

The max speed for the loco was set at 60mph forward and 30mph shunt backwards. I kept reducing these in stages down to 29mph and 8.3mph but the loco still overruns.

 

Looking at my CV table of default settings I pick out a couple it items which may or may not help, I don't know, I have never done this before, I just know 8 in cv8 returns to default so that's handy and well tried.

 

The CV's I am thinking or changing tomorrow, to try have more stopping control are..

CV27 Brake Mode - set at 028

CV 254 Stopping Distance - set at 000 nd 

CV 253 possibly but cautiously Constant Brake - set at 000

 

Comments always welcome

 

Paul

[Nigelcliffe]

Brake Mode, stopping distance and constant brake mode are to do with automated stops from external triggers, such as Asymmetric DCC trackside units (bunch of diodes around a rail gap in the track).   I don't think they will help you. 

 

- Nigel

[Ray H]

11 hours ago, Nigelcliffe said:

Brake Mode, stopping distance and constant brake mode are to do with automated stops from external triggers, such as Asymmetric DCC trackside units (bunch of diodes around a rail gap in the track).   I don't think they will help you. 

 

- Nigel

 

We've just added an ABC braking section -  Asymmetric DCC - to my mate's O gauge layout. The ESU decoders need the two lowest bits of CV27 set - that's normally adding 3 to the previous value. CV 254 and 255 then determine - that's one CV for each direction -  where the train is to stop on the braking section. As Nigel says, I don't think those CVs will be able to help you unless you're using the same system.

[PeteFowler]

Hi,

Did anyone find a solution to this problem as I am having a very similar problem with one of my locos - a Hornby Fowler 2P with a Zen Black Mini decoder and iTrain 5. I can set it up to stop reliably in position going forward but in reverse it continues to run after the speed demands shows zero and stops 6cm past the stop point whatever the reaction delay is set to.