DCC Controller with coast and brake

[pauliebanger]

It may not have replicated what a real driver does with vacuum or air brakes but it did give an impression of mass and inertia. 'Applying the brakes' became the way to control the engine and train rather than the throttle. I used to keep the power on and run only using the brake button. My uncle (also a Driver for many years) always said getting going is easy, the hard bit is stopping.

 

 

Look forward to someone cracking this in a simple and elegant way.

 

I'm sorry, but the ZIMO brake simulation does not do this. You can press the brake key and the application sounds will play, but unless you reduce the regulator position first, no retardation will be effected.

 

What you are describing is a good way to control model trains from an observers perspective, but as you rightly pointed out, it is only really possible with a model. Your uncle would probably not have operated his charges with full regulator, full gear with the brakes applied to slow moderate the speed. The fireman would have been throwing lumps of coal out into the cess for a start. LOL.

 

This throttle over-ride way of braking is available now if you like US outline steamers, though to be fair, the manufacturer also recommends that you reduce the throttle first to be more realistic.

 

The ZIMO implementation is an elegant solution to the provision of simulated Brakes, but it is based upon close examination and use of real loco brakes to give the best simulation possible.

 

Whether it is for you, I can't say, but I know that those who have used it are very enthusiastic.

 

Kind regards,

 

Paul

[pauliebanger]

I suppose you could argue that speed steps are like notches or cut-off but I've never seen a model loco move off in anything but a slightly too slow or far too jerky manner. I would argue that drifting to a halt, checking the rate of deceleration - giving the sense of mass is much more obvious in stopping and a 'apply brake' button, lever or valve would be really usefully in replicating that.

 

I understand how brakes work on the real thing and I've ridden on and watched enough of the real things to know what I am trying to copy in model form and I think that is hard to replicate elegantly or feel connected to by just using one speed control (dial, button or inertia setting).

 

Now I have read this, I think the ZIMO system is for you, despite the need to reduce regulator prior to braking.

 

ZIMO decoders have lots of clever features to satisfy your stated needs, not just braking.

 

With my sound projects for ZIMO, not only do you get the very best slow speed control for which ZIMO has been famous for decades, but you can vary the rate of acceleration simply by the way in which you increase the speed steps. Small increases give modest acceleration (and sound), larger increases give faster acceleration rates (and heavier exhaust sounds).

 

Plus the separately controlled brake feature mentioned elsewhere.

 

ZIMO decoders are all the same, but not all sound projects for them are created equal.

 

Kind regards,

 

Paul

[Junctionmad]

I played again with my Zimo decoder , heres my understanding of the brake feature , this was not a sound equipped zimo

 

 

 

 

As you can see there are two deceleration slopes, CV4 which is the normal  slope that is followed when the throttle is shut off 

 

the brake CV , is the slope followed where a continuous application of the brake function key applied 

 

as you can see the green lines shows, ( the vertical blue line separation distance  represents the time the brake key is pressed )

 

1. a quick dab, decelerating at brake CV rate , resulting in a new lower speed and then loco then continues to decelerate at the CV4 rate , i.e. the brake was briefly applied and then released 

2. a period of no brakes the loco decelerates  at the CV4 rate  ( i.e. coasting  but from a lower speed 

3. a continuous  hold down of the brake function key resulting in the adoption of the brake deceleration curve for a greater period resulting in  significant slowdown as  opposed to the CV 4 slowdown

4. a coast period 

5. brake to stop at the brake CV rate 

 

pressing the brake key continuously  results  in the loco decelerating  at the brake CV setting continuously to stop, ( the turquoise line ) 

 

 

heres a more typical one 

 

where you have longer but fewer presses of the brake function key , with brake release when the button is not pushed 

 

Zimo recommend that there is a considered difference  between  the brake CV and the CV4 deceleration values , otherwise you get very unprototypical action or very little perceived brake action 

 

 

You can call this progressive braking , which is a term I cant find in the ZImo manual ,  but as you can see there is only two acceleration slopes in use.  There is no other progressive slopes , as there are no CVs in which to program them in.

 

Other manufacturers have similar though not identical brake style features ,  for example one of the bachman decoders, automatically reduces the throttle to zero on application of the brake function key , some have basically no brake features ,

 

 

 

this shows ( some what crudely as capacitor discharge curves are not linear , how a DC throttle and inertia brake works, ( I only illustrate a single brake on to a given setting followed by off for simplification ) . The DCC  brake is closer in simulation to a automatic train brake, whereas the DC one is closer to the way a car foot pedal brake works . Unlike the DCC decoder, the DC controller has in essence an infinite variety of brake slopes to chose from , depending on the setting of the brake lever.  however as I said before this is not entirely prototypical . However the use of just two DCC deceleration curves is not prototypical  either, but is used because DCC cannot transmit " analogue " brake position lever values , only binary on offs 

 

in real life none of this is what happens as slow down curves for brakes were decidedly non linear, especially brake block based brakes which had much higher grab at low speeds  and the vacuum brake which progressively applied greater force once the valve was away from the running position to the on position , unlike a car foot pedal , where a fixed continuous force is applied for a given fixed foot pedal force , basically invariable over time . Most people think that the train brake was like a lever operated foot pedal brake on a car, i.e.  the more the brake lever was pulled the more brake pressure was applied , but as I mentioned this isn't what happens on a train brake ( it can happen like that on a steam loco brake for example ) 

 

Dave 

[pauliebanger]

I played again with my Zimo decoder , heres my understanding of the brake feature , this was not a sound equipped zimo

 

 

Screenshot 2016-10-13 01.49.30.png

 

 

As you can see there are two deceleration slopes, CV4 which is the normal  slope that is followed when the throttle is shut off 

 

the brake CV , is the slope followed where a continuous application of the brake function key applied 

 

as you can see the green lines shows, ( the vertical blue line separation distance  represents the time the brake key is pressed )

 

1. a quick dab, decelerating at brake CV rate , resulting in a new lower speed and then loco then continues to decelerate at the CV4 rate , i.e. the brake was briefly applied and then released 

2. a period of no brakes the loco decelerates  at the CV4 rate  ( i.e. coasting  but from a lower speed 

3. a continuous  hold down of the brake function key resulting in the adoption of the brake deceleration curve for a greater period resulting in  significant slowdown as  opposed to the CV 4 slowdown

4. a coast period 

5. brake to stop at the brake CV rate 

 

pressing the brake key continuously  results  in the loco decelerating  at the brake CV setting continuously to stop, ( the turquoise line ) 

 

 

heres a more typical one 

Screenshot 2016-10-13 02.35.01.png

 

where you have longer but fewer presses of the brake function key , with brake release when the button is not pushed 

 

Zimo recommend that there is a considered difference  between  the brake CV and the CV4 deceleration values , otherwise you get very unprototypical action or very little perceived brake action 

 

 

You can call this progressive braking , which is a term I cant find in the ZImo manual ,  but as you can see there is only two acceleration slopes in use.  There is no other progressive slopes , as there are no CVs in which to program them in.

 

Other manufacturers have similar though not identical brake style features ,  for example one of the bachman decoders, automatically reduces the throttle to zero on application of the brake function key , some have basically no brake features ,

 

 

Screenshot 2016-10-13 01.49.30.png

 

this shows ( some what crudely as capacitor discharge curves are not linear , how a DC throttle and inertia brake works, ( I only illustrate a single brake on to a given setting followed by off for simplification ) . The DCC  brake is closer in simulation to a automatic train brake, whereas the DC one is closer to the way a car foot pedal brake works . Unlike the DCC decoder, the DC controller has in essence an infinite variety of brake slopes to chose from , depending on the setting of the brake lever.  however as I said before this is not entirely prototypical . However the use of just two DCC deceleration curves is not prototypical  either, but is used because DCC cannot transmit " analogue " brake position lever values , only binary on offs 

 

in real life none of this is what happens as slow down curves for brakes were decidedly non linear, especially brake block based brakes which had much higher grab at low speeds  and the vacuum brake which progressively applied greater force once the valve was away from the running position to the on position , unlike a car foot pedal , where a fixed continuous force is applied for a given fixed foot pedal force , basically invariable over time . Most people think that the train brake was like a lever operated foot pedal brake on a car, i.e.  the more the brake lever was pulled the more brake pressure was applied , but as I mentioned this isn't what happens on a train brake ( it can happen like that on a steam loco brake for example ) 

 

Dave 

 

Dave,

 

Thank you for putting all this effort into producing the diagrams to illustrate your understanding of how the ZIMO brake system works.

 

It remains incorrect. Either you have deliberately misrepresented what you have observed or your timings are inaccurate.

 

Kind regards,

 

Paul

[Junctionmad]

Dave,

 

Thank you for putting all this effort into producing the diagrams to illustrate your understanding of how the ZIMO brake system works.

 

It remains incorrect. Either you have deliberately misrepresented what you have observed or your timings are inaccurate.

 

Kind regards,

 

Paul

It cannot be anything else Paul. There are no other Cv slopes that can be programmed. The decoder only allows two. While it's difficult to get precise timings without wiring up scopes and using Railcom to get back speeds, I believe what I drew is a reasonable representation based on what I observed on the test track.

 

But , on the other hand if you could direct me to a zimo manual where a different brake function mechanism is documented , I'd b happy to read it and retest, I've yet to see such a manual

 

I will try some further simple tests. , setting the brake CV slope to a large value and equal to cV4 should mean if you are right a continuous pressing of the brake function key will result in near emergency stop times and certainly faster then the cv4 or brake cv setting.

Dave

[Mike Storey]

Whilst the both of you cannot agree on the technicalities, can I just thank you both (with no irony whatsoever, and genuinely) for the effort you have put in to illustrate the necessary issues and for the detailed replies.

 

Between you , my understanding of the issues has increased exponentially, and has given me more confidence in choosing and then partially understanding a great deal more about the interactions of DCC braking, throttle and to some extent, sound, whatever the veracity of the exact measurements. It will still remain something of an ongoing exploration for me, in my quest to have both separate braking and intelligent sound chips, as proffered by Paul.

 

If nothing else, you have both moved me on from entrenched Luddite to enthusiastic experimenter. That is a big win......thank you.

[Junctionmad]

Whilst the both of you cannot agree on the technicalities, can I just thank you both (with no irony whatsoever, and genuinely) for the effort you have put in to illustrate the necessary issues and for the detailed replies.

 

Between you , my understanding of the issues has increased exponentially, and has given me more confidence in choosing and then partially understanding a great deal more about the interactions of DCC braking, throttle and to some extent, sound, whatever the veracity of the exact measurements. It will still remain something of an ongoing exploration for me, in my quest to have both separate braking and intelligent sound chips, as proffered by Paul.

 

If nothing else, you have both moved me on from entrenched Luddite to enthusiastic experimenter. That is a big win......thank you.

Your welcome.

 

It's interesting to try and understand the prototype operation of the vacumn brake , as I did in another thread on rm web. Many people Even drivers have a particular understanding , rather then a technical one. The one thing I can say. Is that the " progressive " brake that Paul claims , in no way emulates the automatic train vacumn brake. The dcc brake button is a big compromise brought upon by the poor dcc implementation of brake in the dcc protocol

[Junctionmad]

just to confirm my tests, I emailed ZImo 

 

heres the answer I got back 

 

"For your information:

You are right, CV#349 is not progressive (even if you define the assigned function key in CV#309 as moment/trigger key) and it simple replaces the adjusted braking value of CV#4 with the braking value defined in CV#349. 

Best regards,
Stephan Hubinger
 
ZIMO Elektronik GmbH
Schönbrunner Straße 188
1120 Wien, ÖSTERREICH
Telnr.: +43 1 8131007 13"

 

straight from the horses mouth . so to speak 

[pauliebanger]

just to confirm my tests, I emailed ZImo 

 

heres the answer I got back 

 

"For your information:

You are right, CV#349 is not progressive (even if you define the assigned function key in CV#309 as moment/trigger key) and it simple replaces the adjusted braking value of CV#4 with the braking value defined in CV#349. 

 

Best regards,

Stephan Hubinger

 

ZIMO Elektronik GmbH

Schönbrunner Straße 188

1120 Wien, ÖSTERREICH

Telnr.: +43 1 8131007 13"

 

straight from the horses mouth . so to speak 

 

Dave,

 

I had a interesting reply from Mr Hubinger today too, so I may have the answer to why we get different results.

 

If you can tell us which ZIMO decoder you are using for your tests and which software version is loaded I believe I can explain the apparent discrepancy to everyone's satisfaction. (CV7 will give the main version number and CV65 will give the sub-version number).

 

It would be helpful if you also listed the values of CV4, CV309 and CV349 which you have programmed, though that is not essential.

 

Kind regards,

 

Paul