Re: DCC Controller Features

Do you consider that I have no knowledge of that subject?

As have I for my main prototype and for the NZR for the 1950s and 1990s.

We're about equal so far.

Would you kindly assume I don't suffer from your narrow band of knowledge.

- that you're being obtuse for the sake of it.

- that I'm answering the questions asked of me.

- that I have experience of prototypes different to those you have.

- that I'm not fitting the prototype to the limitations of DCC.

Roger - how long ago was the PST dropped to 7% ?

PS - basic decoders = low $20s.

Bill

"B Dixon"

GST is 7% and in BC, the Provincial Sales Tax is 7.5%.

Thus, 7% plus 7.5% = 14.5%

Decoders in my local stores, still Can$30, plus tax.

-- Cheers Roger T.

Home of the Great Eastern Railway

-- Cheers Roger T.

Home of the Great Eastern Railway

I regret that it has been so long since anyone outlined the "limitations" of DCC that I have forgotten what they wrote. I think the erudite T. Flynn was the one I read, but I am interested to read what G. Procter's ideas of limitations are. Do you care to outline them with accompanying explanations as to why they are perceived as limitations, G. Procter? Understandably, some will be obvious, but others may not. Incidentally, T. Flynn says that your knowledge of electronics and DCC exceeds his. Therefore I will not talk to him about these matters any more, preferring instead to discuss your much more vast experience. So then, if you have time, and are so inclined, please hold forth on the limitations of DCC.

Regards, Obnoxious Pratt.

As was pointed out to you, we were talking about uncoupling engines on the fly, as in helper service or doubleheading.

Mike Tennent "IronPenguin"

I don't know if Terry has more or less knowledge on electronics and/or DCC than I and I consider it dangerous to reach such conclusions. I think Terry's comment was a response to someone claiming I had absolutely no knowledge on either subject rather than an estimation of the distance each of us has travelled on the road to DCC enlightenment.

Well, it's the day before Christmas, I have a business to run, the lawns to mow, a trip to the rubbish dump and a household full of visiting rellies to entertain ... There may be moments when I feel like hidding behind the computer ...

Problems regarding listing "the limitations" of DCC are that some are absolute, some are comparisons with analogue and some of those affecting my layout date back to the time of conception of this layout. In addition, some of the features of DCC that others find important or even indispensible are valueless to me. eg. Lighting functions. My prototype fitted gas or petroleum lanterns at each corner. They lit them at the front for forward travel, at the rear for backward travel and all four for yard work. I can do this in analogue without any problems. You can offer me a decoder with 2, 10 or a 100 lighting functions and I'll remain unmoved.

Ok, I missed the "on the fly" bit. Header locos on my prototype cannot be uncoupled on the fly as they used screw couplers. I didn't even know that was a possibility in the US! Banking locos (on my prototype) at the rear were not coupled to the train, so separating on the fly is the norm. Control is simply by switching cabs for the rear blocks so that the bankers are controlled by a different hand-held. The PCC then classes the banker(s) as a separate train and the next signal automatically will be set at halt.

Regards, Greg.P.

Very well, I understand. It is the same for me as well regarding the season. At some later time when you do feel so inclined, let us begin a new thread: "Limitations of DCC". Then we may put this tired old one to bed now that we have changed topics.

Regards, Obnoxious Pratt.

It was once, but was never safe and was mostly frowned upon. Today it is absolutely forbidden for a banker to cut-off on the fly except in very special circumstances, for which special measures are implemented. It is even possible that these are not allowed any more either. But, North America is a very big place and I cannot keep up with all of it all the time.

In North America, the helper (banker) is required to couple to the train and configure the brake valving system such that the brakes are controlled by the leading locomotive. This mostly negates cutting off on the fly. Technological progress has made it possible to distribute power throughout the length of the train instead of concentrating it all at the front, and more powerful locomotives have severely thinned the ranks of banking engines here. But, this is modern stuff and is outside my sphere of interest. I model first generation diesel and prefer dense urban/industrial railroading.

Regards, Obnoxious Pratt.

Yes, but there is sometimes a communication problem that has to be made clear to all sides. We are separated by a common language, it was once said. There is no harm in making sure you understand what the other guy means, to wit: block/section in another part of this thread.

Fair enough

wandering around

Well, yes, but my point was that the control of the locomotive is inside the locomotive. That part is important becasue it is what makes DCC so different from other methods, particularly the one we are discussing here.

All right, I wasn't being literal about the driver. I was trying to put forth the idea that the driver was mentally inside the loco or that the driver could think in ways other than those connected with the workings of the layouts OS.

The part about the computer is an actuality, The decoders do have a microprocessor of their own that processes data and outputs data to make the motor operate. But you know that.

rails whether

is that you

situation you

Same with DCC, but not if you operate with only two wires to the track. You can do it, but prudence suggests that you divide the thing into power districts to prevent a short from shutting the whole thing off. The difference is that the power districts are invisible to the user and do not require any supporting circuitry beyond a cheap, self resetting circuit breaker. You can get a module from one of the DCC vendors that can manage four power districts, but I share T. Flynn's penchant for economy and do not use the module. My way is cheaper, but not as pretty. It is also easy enough for a total electrical no-nothing to connect.

Yes, the big difference, and the most important one, is that there is no requirement for anyone to understand and manipulate the layout's OS. All you need do is concentrate on operating the trains. All the power distribution becomes a non-issue.

That is a strange reason

track (in either

What do you mean by that? my handeld unit is sending information to only the loco that I have selected and no other. It makes no difference where that loco is on the railway, it responds to that handheld unit only, the fact that the signals from that handheld are propagated over the entire railroad is irrelevant. Just as when you tune your tele to a particular station, you get that station and no other. The fact that every other station is broadcasting everywhere at the same time, or the signals for all the channels are on the same strand of cable is inconsequential. your machine only responds to the one to which you wish it to respond.

on your layout

same line then

(prototype) block.

I think you are missing the meaning here. Any loco can run on any track at any time in either direction. This simply means that they can all operate independently of one another and that there is no dependency on track voltage or polarity. It doesn't mean that you can run around like mad mice ( you can, but why would you unless you're an idiot) Other than the fact that there is no block assignment or selection such as you have, there is precious little difference. Realistic prototypical operation is enhanced by not having to allow for such things as are limited by hard divisions of power zones and the limitation that every loco in a zone will be equally affected by the throttle setting for that zone. On main line trains it is not as much an issue as in yards. Trying to run realistic yard operations with conventional analog can get to be very trying. Trying enough to take the fun out of it. Remember, I am an old guy, probably older than you, and I have had fifty years of analog experience to compare to my DCC experience. It is very clear to me which one is more fun and easier for me to use. DCC wins, hands down.

Regards, Obnoxious Pratt.

I'm sure that same (braking) change took place on my prototype, but not during the period I model.

The strength of the couplers was the limiting factor in Germany and here in NZ. I'm not aware of any banking in either country. Here in NZ the introduction of second generation diesels forced the upgrading of couplings on older rolling stock.

Is the US "sometimes" used in the same manner as the English "usually"? ;-)

I thought I was speaking US!

wandering around

The major advantage there is that there is maximum voltage on the rails most of the time. However, I moved to PWM about 30+ years ago so the advantage is minimal.

Again, I don't see much difference with what I have achieved with analogue. If I clear the main line while operating solo or use another operator or the PC as the signalman, the blocks automatically link loco and cab. I can drive the loco as though I had DCC. The exception is in grouping together locos, where manipulating track power switches seems to be unavoidable.

I know that.

of rails whether

exception is that you

situation you

I'd get terrible withdrawal symptoms!!! A long time ago I started soldering a feed to every separate rail length and I've never regretted it!

I would still need to wire a detector into every signal block, which would need to be isolated from every other signal block. All that would be different between the two systems is what hangs on the end of each of those wires.

That sounds just like my layout - the difference being that I need to identify the track block my loco is standing on, and the destination track and punch them into the keypad, while you need to read those 2mm high numbers on the side of your loco and punch them into your keypad. The computer on my layout selects the route and links the hand-held to each block in sequence so far as the signals allow.

Not if you think about it. For example, no way do I wish to emulate the prototype's ability to have disasterous collisions.

track (in either

This is rather like the TV cable company's sales pitch that you can get 204 (or whatever) TV channels and my response that I almost never watch more than one at a time! If I can link my hand-held and my loco at all times without conflicting with any other, where is your advantage?

anywhere on your layout

the same line then

(prototype) block.

I already achieve that, with a minor limitation.

Let's skip ove that bit.

But my prototype uses block asignment.

You still have to select. You pick up your hand-held, read the number of your loco and type it into the keyboard. I pick up my hand-held, read the number of the block and type it into the keyboard.

Ok, yard work is easier with DCC, analogue is easier when modelling a prototypical block system. I was forced to make a choice - analogue came out ahead for my requirements. My second layout is a 4'x18" industrial module on which I use DCC. Now what I need is a decoder which operates on both and retains the operating functions/parameters of DCC on DC plus adds the ability to switch off the traction current through a function address.

Regards, Greg.P.

loco and type it into

into the keyboard.

One big difference is that I can go out and buy a DCC system with this capability, to do it your way with DC I have to do a lot of design and build work and set up the computer with lots of I/O boards and a lot of layout specific configuration.

prototypical block system.

functions/parameters

function address.

Any decoder with programming on the main will do this via adjustment to CV29 to enable or disable DC operation, but could you explain why please. If operating on DCC then the traction current can be turned off by the speed control, no need to use a function. If you are on DC you can't send it a function command anyway.

Keith Make friends in the hobby. Visit Garratt photos for the big steam lovers.

loco and type it into

it into the keyboard.

Mk 1 of the system was an off the shelf computer interface kitset. Mk 2 of the system was the old Arnold DCC CU and Interface driving all turnouts and block relays. Mk 3 is a self designed interface and some fairly basic electronic hardware. I'm not an electronics expert, just an occassional dabbler. The point of Mk 3 is to do away with layout specific componentry. Yes, the software is layout specific, but that would happen with analogue or DCC control.

prototypical block system.

functions/parameters

a function address.

If I was to go totally DCC then I would want the locos to brake for DC on the track. That would resolve my computer operation of the main line block system, although probably badly due to varying braking distances - complete redesign of block lengths to suit DCC - yuck!

The better solution seems to be DCC operation of yard areas and DC operation of the main line, with yard locos also operating as bankers on the M/L.

OK, I need a decoder that retains it's speed mapping and EMF feed-back in DC operation. No-ones seems able to tell me which decoders do this, if any.

My current system requires loco length sub-blocks to enable locos to be coupled together - the only block switches required under my present system. A DCC function traction on/off would eliminate most of those.

Of course I can. :-) (my electronics abilities are limited to cobbling together bits of circuits - DCC signals over-riding DC isn't difficult)

It would seem to me to be preferable to make my analogue decoder DCC compatible rather than to start a whole new protocol.

Regards, Greg.P.

track. That would resolve

due to varying braking

The recent decoders allow you to set the required stopping distance in this scenario and claim that this distance will be independent of the speed when braking is initiated. I haven't tried it 'cos I have no need for it. Suggest you test one out. (Check the Lenz or Zimo websites)

the main line, with yard

operation. No-ones seems

Pretty much all of them as I understand it, the operation decoder to motor, is as set up by the CVs but on DC the recieved voltage is used to set the required speed and its not going to be as precise as the digital command. It does need to be a smooth DC to get good control.

together - the only

would eliminate most of

But then you would have to turn on your override to send the command, so you may as well just send DCC zero speed packets.

DCC signals over-riding DC

But then its not DC anymore its DCC and the decoder will obey the DCC command anyway

rather than to start a

If it has a 'protocol' its not analogue anymore! And how does this concept differ from a DCC decoder that is analogue compatible? (90% of those on the market).

Sorry, I still don't understand what you want to do that needs this function operated power off. Could you try and explain in a bit more detail.

Our experience at MERG is that DIY decoders are not worth the effort unless you go for a really high end job. Assembly in small sizes is pretty challenging so a kit cost of £10 does not compete with an off the shelf decoder at the same price. Even when the kit unit is silent drive, back emf and five functions with lots of special effects and the commercial unit is just a basic job with one or two functions.

Happy Christmas Keith Make friends in the hobby. Visit Garratt photos for the big steam lovers.

Sometimes.

That's a bit like me trying to speak NZ. It only works sometimes.

the time. However,

The last analog I did was 20 years ago. It was PWM and had homebuilt controllers much like the ones you describe. It worked fine right up until I got introduced to DCC. I was operating on CTC-80 layouts from the beginning of CTC-16, but I am not interested in electronics to any degree and so elected not to go the effort of building my own CTC-XX control system. I did like operating on it though. The absence of the need to select blocks to operate the railroad and the ability to independently control a loco sitting right next another was intriguing.

to be isolated from

is what hangs on the

Well, yes. Once you cross over into signaling a model railway things get exponentially complex regardless of analog or DCC. Which is why I like DCC so much. It nearly removes the first layer of complexity from the equation.

the track block my

while you need to

block in sequence so

This is one layer of complexity the DCC removes while still maintaining the same end result. You do still have to read the locomotive number if you do your addressing that way, but there are all kinds of ways to address a decoder. Some trains that are used for moving scenery have only a train number for the address. There is nothing to read except the train card supplied on the call board. You call up address 37, for example, and the train that moves is the one you are to drive this time out.

disasterous collisions.

No one does that except Gomez Addams.

Suits me, since it is obviously not an issue for either one of us.

I mean that there is no need to choose to feed power to any particular electrical block since they are all powered all the time with the AC current source and the individual locomotives are where the control resides via the handheld. But you already know that.

Permission to occupy a specific segment of the right of way for the purpose of traversing the railroad is another matter entirely. It doesn't matter one whit whether you are analog or DCC in this case. The train or engine must have permission to occupy the right of way in a specific place, specific direction and for a specific time.

This never changes if you operate prototypically in North America. I would guess that it is much the same for New Zealand or Germany as well.

loco and type it into

into the keyboard.

OK, six of one and a half-dozen of the other.

prototypical block system.

functions/parameters

function address.

You don't need to do that. Just set the DCC packet speed information to zero and it's done. The lok won't move, just the same as if you'd cut the power, but the one right next to it will, if need be.

Regards and Happy Christmas. Obnoxious Pratt.

Don't know what backwater of BC you live in Roger but the PST was dropped to 7% a few months ago just before the Surrey by-election that the Liberals tried to buy but lost.

Bill Dixon

On reflection, I'm inclined to agree with you, on that point at least.

then DCC is for you. If your prototype is otherwise then analogue may be better suited to your needs.

But I can't agree that DCC is unsuited to modelling a prototype that uses block working.

I have a friend who models a local railway as it was in the 60s - single line worked with Ordinary Train Staff. As on the prototype, there is no train detection or track circuiting. Authority to enter the section is by possession of the staff and fixed signals. At crossing loops the train crew work themselves through - there are no station or signalbox staff. On arrival at a loop the train stops at the home signal, the fireman walks to the ground frame and unlocks it, clears the home signal, the train enters the loop, and the fireman sinks the staff.

The guard then withdraws the staff for the next section, gives it to the driver, clears the starting signal, the train pulls forward until it clears the loop and then stops, the guard returns the signal to stop, locks up the frame, and the train departs.

All this is replicated on the model, using miniature staffs and manually operated signals. It is a prototypical form of block working, and it is operated by DCC with no difficulty whatsoever.

I'd be interested in hearing why you think this can't be done...