DCC Decoders for Cab Cars/End Cars

[CaptOblivious]

	TF4	73900	FL4	FL12	LokPilot Fx micro V3.0	M1	Z2	LF101XF	DF12r3	DF11r3
Manufacturer	Digitrax	Uhlenbrock	TCS	Kato	ESU	TCS	TCS	Lenz	NGDCC	NGDCC
Rating	☆☆☆☆	★★☆☆	★★☆☆	★★☆☆ /★★★☆	★★★☆	★★★☆	★★★☆	★★★☆	★★★★	★★★★
Price	$21	$25	$19	$16	$40	$32	$35	$25	$23	$20
Price per Star	$∞	$13	$10	$8/$6	$13	$11	$12	$9	$6	$5
Recommended?			✓	✓				✓
Height	4.1mm	2.4m	3.43mm		3.5mm	3.43mm	2.79mm	2.6mm	2.3mm	2.3mm
Width	7.8mm	7.5mm	9.14mm		9mm	9.12mm	6.6mm	12mm	11.5mm	11.5mm
Length	11.7mm	10.8mm	14.86mm		13.5mm	14.4mm	12.95mm	24.1mm	18.5mm	18mm
Functions	4	4	4	2	4	4	4	6	3	2
Dirctional Lights?	✕	◯	◯	◯	◯	◯	◯	◯	◯	◯
Bi-Polar?	✕	✕	✕	✕	✕	◯	◯	◯	◯	◯
Dimmable Lights?	✕	✕	◯	✕	◯	◯	◯	◯	◯	◯
4-Digit Address?	◯	◯	◯	◯	◯	◯	◯	◯	◯	◯
Transponding?	◯	✕	✕	◯	✕	✕	✕	✕	✕	✕
RailCom?	✕	✕	✕	✕	◯	✕	✕	✕	✕	✕
Max Current (cont. func.)	125mA	600mA	200mA	125mA	140mA	1200mA /100mA	1000mA /60mA	150mA	50mA /7mA	50mA
Max Current (peak func.)	250mA
Max Current (cont. total)		600mA	500mA		280mA	1300mA	1120mA		120mA	140mA
Max Current (peak total)			1000mA			2000mA	2000mA

Stars
☆☆☆☆ Do not use. Unsuitable for cab cars.
★☆☆☆ Adequate. Suitable for cab cars, but you could do better.
★★☆☆ Fine. Suitable for cab cars. Often will have the best feature set for the least price.
★★★☆ Good. Well suited to cab cars. Has more or better features than most.
★★★★ Perfect! An ideal decoder for cab cars. Has most or all of the best features, but is often also the most expensive.

Price per Star
This is the ratio of the decoder’s price to it’s rating in stars. The number is a rough guide to the cost-to-benfit ratio. Lower numbers represent a better cost-to-benefit ratio; higher numbers represent a worse cost-to-benefit ratio.

Directional Lighting
When a prototypical MU is moving, the headlights at the front of the train are on, and the taillights at the rear of the train are on. When the train switches direction, the headlights and taillights switch too. A decoder that supports directional lighting will automatically switch the headlights and taillights depending on the direction of travel set by the throttle, with no user intervention necessary. This is a very important feature for a function decoder used in cab cars to have.

Bi-Polar Circuit Capability
A bi-polar circuit is simply a circuit with two leads that behaves differently depending on the direction of current across the leads. The directional lightboards in cab cars are bi-polar circuits: When the current flows one way, the headlights come on. When the current flows the other way, the headlights go off, and the taillights come on.

A DCC decoder function lead can only control one light circuit at a time, because they can only generate current flow in one direction. Thus, the lightboards must typically be cut apart into two distinct lighting circuits before a decoder’s function leads can be attached. However, some lightboards are too small or delicate to easily cut apart in the way needed. In these cases, a decoder that can provide current flow in two directions can be connected directly to the leads of the lightboard without having to cut it apart. This is a tremendously helpful feature, but is only rarely necessary.

Dimmable Headlights
As in the United States, Japanese rules of operation require trains to dim their headlights when passing or standing at passenger stations. Although a subtle feature, many modelers enjoy prototypical lighting effects in their trains. Typically, a decoder that supports this feature will dim the lights when F4 is pressed. Any function decoder that supports “Rule 17″ operation of the lights will support this feature.


Bidirectional Communications
RailCom and Transponding are two different systems of bidirectional communications over DCC. Normally, DCC is a one-way signal: From the command-station to the decoder. There is normally no method for DCC decoders to respond. RailCom and Transponding are methods for the decoder to send a response to the command-station. This is really useful for automated control of a layout, but is not a necessary feature to implement basic block occupancy detection, although both methods require a block occupancy detector detector to work. I won’t get into a discussion of the advantages or disadvantages of each system; you can read more about those elsewhere on the Internet.

RailCom is an open standard developed by Lenz and adopted by the NMRA as a Recommended Practice for DCC. That is, it is now an official, if optional, part of the DCC specifications. RailCom responses can be detected by a Lenz LRC130 RailCom detectors and reported to a computer via the Lenz LRC135 RailComBus USB adapter.

Transponding is Digitrax’s proprietary standard for bidirectional communication, and is currently only implemented in Digitrax decoders and Kato decoders designed by Digitrax. Transponding responses are detected by a Digitrax RX4 detectors, which must themselves be attached to a Digitrax BDL168 block occupancy detector. Transponding oddts can be communicated to a computer via the Digitrax PR3 LocoNet USB adapter.


Maximum Current Ratings
The current rating of a decoder tells you the largest load you can connect to the decoder. Each light, motor, speaker, etc., draws a certain amount of current; attaching too many will cause the decoder to overheat and perhaps odd die.

A manufacturer often lists two or more different current ratings. A current rating is either for each function individually, or the total current for all functions combined. Moreover, a current rating is either a continuous rating or peak rating.

Continuous Current per Function is the amount of current a decoder function lead can handle over an indefinite time period. For example, if the literature claims a 125mA continuous function current rating, then you can attach a lamp that draws up to 125mA to that function, and leave it on as long as you please.

Peak Current per Function is the amount of current a decoder function lead can handle for short bursts. Incandescent lamps, when they first turn on, have an inrush current that is ten times the current draw of that lamp. For example, a lamp that is rated as drawing 50mA will actually draw 500mA very briefly when it is turned on. So this rating is important to know when you are using incandescent lamps. LEDs do not have a significant inrush current.

Continuous Total Current is the total amount of current that the decoder can supply for all functions combined over an indefinite time period. The sum of the current draw of all lamps must not exceed this amount. This may limit the number of lamps or other loads you can attach to the decoder.

Peak Total Current is the total amount of current that the the decoder can supply for all functions combined for short bursts. This is particularly important for motor decoders, where the stall current of the motor (the amount of current the motor draws when it is stalled or locks-up) must be less than this number. Unless you will be using a large number of incandescent lamps (see above), this number is relatively unimportant for function decoders.

[CaptOblivious]

Well, I just posted this to my blog:
http://akihabara.artificial-science.org/dcc/dcc-for-cab-cars/

Perhaps I should update this page accordingly ;)

[CaptOblivious]

Shuhei Nagasue-san, the head of NGDCC, sent me a very nice email last night, telling me that I've incorrectly undersold his competitor's product! No American company would ever do that.

Anyway, he point out two inaccuracies in my description of the FL12: First, it does support 4-digit addressing. Indeed, reviewing the manual, it clearly does. I'm not sure where I got that it didn't. Second, it does support CV readback in the programming track, but that the loads usually attached are too small to be detected by the programmer, so in practice they cannot be readback.

The lack of 4-digit addressing struck me as a massive failure on the part of the FL12. So, I have bumped up its rating in light of this information.

[alpineaustralia]

I also thought it didnt support 4 digit addressing.
I am going to have to check this one out and get back to you.

[alpineaustralia]

Attached instructions for FL12 describe it only as having 2 digit addressing

[CaptOblivious]

I thought so too!

But, look again at the top of page 2. The bit we focused on is about CV01, which is the 2-digit address CV.

I managed to program my E231-500, motor car and cab cars, with 4-digit addresses last night!
The trick is to manually set CV17 and CV18, (and then configuration CV29, too) rather than rely on your programmers automatic address setting feature.

You will find this link helpful:
http://www.ruppweb.org/Xray/comp/decoder.htm

[mrpig]

Capt O your a genius, shows how much I rely on the auto features of the system instead of RTFM.

My N700 now has a more intuitive address, now if I can get the N in there somehow.......

This means the FR11 is back in the running for interior lighting as well.......... That's gonna hurt, I need 130 of them ::)

[alpineaustralia]

Capt what do you set CV29 to?

[CaptOblivious]

Capt what do you set CV29 to?

38 will do (same settings as default value of 6, except for 4-digit addressing instead of 2-digit)
(basically, just add 32 to whatever value you were using before, if not the default)

[mrpig]

I have just finished installing my first TCS FL4 for end car use into a Kato 800 series. My install is almost identical to Martijn's, so I won't bother to upload it. I made a discovery though, I thought I had fried the white led. I did a quick confidence check as soon as I finished soldering to make sure all was good before closing up and programming. The white led would not work.

I pressed on and started to set the CV's thinking I would change the led when finished. Suddenly the white led started working. It appears that when using the single resistor on the light board with the blue wire instead of separate resistors on each function, the red led steals all the power if they are both set to on.

Also note that there are 2 lots of CV's for each function. This is what I ended up with.
CV51=0   CV35=1
CV52=16  CV36=2

This gives fwd on green and rev on purple

[CaptOblivious]

I pressed on and started to set the CV's thinking I would change the led when finished. Suddenly the white led started working. It appears that when using the single resistor on the light board with the blue wire instead of separate resistors on each function, the red led steals all the power if they are both set to on.

That's interesting, but I suspect more a function of the lightboard design than the decoder.

I have noticed that the FL4 takes a little bit to find its feet? I don't know how else to describe the phenomenon, but I've see it with several decoders: The decoder doesn't appear to work until it's been on the track for about 10-20 seconds. Meanwhile you're fiddling with the controls and the CV programming, when suddenly, after mucking about with CVs you put them back where they were originally. Then the damned thing works.

Does anyone else have this experience, or is it just me?

Anyway, I wonder if that wasn't what was going on in your case, mrpig. Glad to see it's working out now.

[mrpig]

Cap - I have done some thinking on this led thing, didn't that tax the grey matter. Been over twenty years since I did any circuit theory.
It is all to do with the light board design and the different turn on voltages for red and white led's.

Any decoder will give the same results. It was just more obvious with the FL4 because of its default programming.

I will draw up the circuit in a new thread and write up the theory to go with it for anyone interested

[CaptOblivious]

I wondered if it was something like that (hence the comment that it was more likely the lightboard than the decoder), but I don't know enough to articulate what I was thinking. I would love to see this phenomenon clearly written up.

[alpineaustralia]

Capt
Do you know anything about the TCS FL2?
I assume that it is the same as the FL4 but only with 2 functions. I tried to read the manual for it and it was impossible to decpher whether it was directional (http://www.tcsdcc.com/Additional.pdf).

By directional I mean plainly and simply that it will control 2 lights (ie. the headlight and the taillight) by automatically:
 - turning the headlight on and turning the taillight off when moving forward; and
 - turning the taillight on and turning the headlight off when moving in reverse?

Will the TCS FL2 or FL4 do this?

[CaptOblivious]

Capt
Do you know anything about the TCS FL2?
I assume that it is the same as the FL4 but only with 2 functions. I tried to read the manual for it and it was impossible to decpher whether it was directional (http://www.tcsdcc.com/Additional.pdf).

By directional I mean plainly and simply that it will control 2 lights (ie. the headlight and the taillight) by automatically:
 - turning the headlight on and turning the taillight off when moving forward; and
 - turning the taillight on and turning the headlight off when moving in reverse?

Will the TCS FL2 or FL4 do this?

Both will do exactly what you want. I am very pleased with my first FL4, and will be buying more. The FL2, oddly enough, is quite a bit larger, which is why it didn't make it into this review.

I'll post some sample CVs for TCS decoders later today.

[CaptOblivious]

OK, to program the TCS FL2 or FL4 to have directional headlights, here's how to do it.

First, notice that we'll be using the Green and Purple function leads (mapped by default to F1 and F2 respectively; function-only decoders don't come with White and Yellow function leads).

Suppose that the Green (F1) is wired to the headlights, and the Purple (F2) to the taillights.
To make the headlights (Green/F1) come on when the train is moving forward:
CV51 = 0
And the taillights (Purple/F2) come on in reverse:
CV52 = 16

For the car at the other end, just reverse those values.

Source:
http://www.tcsdcc.com/pdf/Advanced%20X%20Features%20v1.pdf

TCS tries to be helpful, by organizing programming tasks into tables. Table 11 covers assigning lighting effects to function leads. However, there is no one place to get a complete list of all the tables, and sometimes there are different versions of a table (I count at least two and maybe three versions of Table 11 across various literature). Grr. Can get very confusing.

[mrpig]

I also remap the green and purple wires on the FL4 so they both operate on F0 just like white and yellow on a normal decoder with motor control. To do this set the following CV's.

CV35=1
CV36=2

[CaptOblivious]

I also remap the green and purple wires on the FL4 so they both operate on F0 just like white and yellow on a normal decoder with motor control. To do this set the following CV's.

CV35=1
CV36=2

Thanks! Forgot to mention that. Remapping the functions like this does not require you to redo the CVs which select the lighting effect (unlike on Digitrax decoders).

[alpineaustralia]

So in order to work just like (say) the kato decoder, I need to program:

CV35=1
CV36=2
To make the headlights (Green/F0) come on when the train is moving forward:
CV51 = 0
And the taillights (Purple/F0) come on in reverse:
CV52 = 16

Is that correct?

[CaptOblivious]

You are correct, sir!

So in order to work just like (say) the kato decoder, I need to program:

CV35=1
CV36=2
To make the headlights (Green/F0) come on when the train is moving forward:
CV51 = 0
And the taillights (Purple/F0) come on in reverse:
CV52 = 16

Is that correct?

[alpineaustralia]

you are a scholar and gentlemen ! thank you

[mrpig]

And don't forget that if you wired up both end cars identical, you will probably have to add 1 to whatever value you have in cv29 for the tail end car only ( cos its facing the other way ).


Now how about automatic headlight dimming when stopped, aka, rule 17.
Set CV61=16 (dim when stopped)
      CV64= 2-6 for led's, 12-18 for bulbs.  I started at 5 but adjust to your liking.
      CV51=8

Note this is for a FL4. Haven't played with the other decoders yet.

[alpineaustralia]

And don't forget that if you wired up both end cars identical, you will probably have to add 1 to whatever value you have in cv29 for the tail end car only ( cos its facing the other way ).

I thought all you needed to do was reverse the purple and green. This last sentence confuses me a little.
Do I also need to add 1 to cv29 if I reverse the purple and green?

[mrpig]

And don't forget that if you wired up both end cars identical

No need to change cv29 if you reverse green and purple. Only if both cars are wired exactly the same.
Sorry for the confusion.

[alpineaustralia]

my thanks to you also mr pig.

[quinntopia]

Purple and Green wires! Oh No!  :o

What about us poor folks using using the Lenz LF101XF?

We're really talking about whatever color wires are the function leads for the lights, right? In the case of the Lenz LF101XF, those would be different, right??  :-\



They seem to answer this in the instructions, but I am assuming by reversing the yellow and white wires on one of the cab car ends I can also avoid the CV29 change?

[CaptOblivious]

Purple and Green wires! Oh No!  :o

What about us poor folks using using the Lenz LF101XF?

We're really talking about whatever color wires are the function leads for the lights, right? In the case of the Lenz LF101XF, those would be different, right??  :-\

They seem to answer this in the instructions, but I am assuming by reversing the yellow and white wires on one of the cab car ends I can also avoid the CV29 change?

The TCS function decoders presume (falsely in our case!) that they will be installed with a 2-function motor decoder that provides the yellow and white-colored leads. So, to avoid confusion, the function decoders start with green & purple.

The Lenz function decoder makes no such presumption. And so you are correct that you should use the Yellow and White leads for the lights in your cab car. And likewise, yes, reversing the leads on the other end avoids reprogramming for the trailing cab car.

[The_Ghan]

Has anyone identified the contacts on the Kato FL12 decoder?  A diagram of some sort would be great.

I think I've decided to use that decoder for my cab cars - I'm using transponding and it seems to be the best choice in that regard.

Cheers

The_Ghan.

[Martijn Meerts]

A quick note on the "dimmable lights", quite a few decoders allow you to set the brightness of the lights in a CV. While not as easy as pressing function button to dim the light, you can still dim the lights.

[The_Ghan]

Good point Martijn.  There is, apparently, no perfect cab decoder.

Cheers

The_Ghan

[CaptOblivious]

Has anyone identified the contacts on the Kato FL12 decoder?  A diagram of some sort would be great.

I think I've decided to use that decoder for my cab cars - I'm using transponding and it seems to be the best choice in that regard.

Cheers

The_Ghan.

There is a site out there with a diagram, but I can't find it at the moment. In the meantime, this site might be helpful. He uses the FL12 wired in for nearly everything it seems. Good photos here:
http://blogs.yahoo.co.jp/okiraku_dcc/62731203.html
http://blogs.yahoo.co.jp/okiraku_dcc/62928390.html
http://blogs.yahoo.co.jp/okiraku_dcc/62313457.html

Don

[Martijn Meerts]

True, there's also no perfect loco decoder, no perfect turnout decoder, no perfect digital system etc =)

With decoders, it really depends on the situation. The cheap ones often lack quite a lot of features, but then again, not everyone wants/needs those features. Often available space is a problem too, in which case you may be forced to go with a small, more expense and less feature rich decoder.

I've been quite happy with the Lenz Gold mini, and now with the Lenz Silver+ mini, but they're not the cheapest and not everyone will need to features it has. For me, the size of the Silver+ mini is what makes me buy it. I don't think there's any other decoder with as much functionality in such a small package.

I also buy the Uhlenbrock 73900, also for the physical size of the decoder. I can usually fit it where it needs to go. Of course, I need to be careful with connecting it, and sometimes need to do some major modifications to light boards. A bi-polar one would have been a lot easier.

Again though, a good soldering station helps a bunch.

[The_Ghan]

Has anyone identified the contacts on the Kato FL12 decoder?  A diagram of some sort would be great.

I think I've decided to use that decoder for my cab cars - I'm using transponding and it seems to be the best choice in that regard.

Cheers

The_Ghan.

There is a site out there with a diagram, but I can't find it at the moment. In the meantime, this site might be helpful. He uses the FL12 wired in for nearly everything it seems. Good photos here:
http://blogs.yahoo.co.jp/okiraku_dcc/62731203.html
http://blogs.yahoo.co.jp/okiraku_dcc/62928390.html
http://blogs.yahoo.co.jp/okiraku_dcc/62313457.html

Don

Don,

That's a great start. I can almost work it out from a couple of those photos.  I might have to get the breadboard out.  In the meantime, please let me know if you come across the wiring diagram.

Unfortunately, that guy doesn't seem to be modifying the LED board and has both head and tail lights illuminated at the same time.  I plan to modify the boards, probably with my stanly knife and engraver.

Cheers

The_Ghan

[Martijn Meerts]

I was working on some function decoder installs recently (Uhlenbrock 73900, 3 in total), and while everything went smooth enough, programming the things just didn't seem to work. Or at least, not entirely. Every time I tried to read a CV, I'd either get an error message (ERROR 02 on the Lenz LZV100/LH100 combo) or nothing at all for about 5 minutes (ESU ECoS 50200). Rarely I got a return value with the ECoS, but it was always a bogus value.

Trying to write values to the CV's gave me errors as well, however, the values (or some at least) did get programmed. For example, I was able to change the address, as well as make the lights blink.

To make things worse, my Kato 800 series also has the 73900 decoders installed, and the CV's on those can be read without problems.

After some searching around, I found out that in order to read CV's, there HAS to be something connected to the A1 output (white wire, usually front head lights). Not only that, but whatever's connected needs to be drawing at least 60mA (this seems to be an NMRA standard.) Obviously, an LED doesn't draw 60mA, and LEDs are just what's installed in the cars.

Strangely though, the 800 series cab cars have LEDs as well, and yet those can be read. Those decoders may have an older firmware though...


Another thing I noticed, the 2 end cars of Kato's Orient Express base car set seem to make this barely audible noise when put on the track. It's almost like they're shorting out ever so slightly. I have no idea what's causing it though, because it's just an LED, a resistor and the function decoder.

[CaptOblivious]

I've had a few function decoder installs make those noises you describe, Martijn. Never was able to determine what the cause was, but it doesn't seem to be making a problem.

I can read decoders on the programming track pulling less than 60mA just fine, even though it doesn't meet spec; I suspect the Digitrax Zephyr might be more sensitive than is necessary to meet the requirements. That not every CV you attempted to program stuck is not a good sign that it's only an undercurrent issue. Have you tried reseting them? I might wonder if it was a decoder lock issue, that at some point you accidentally programmed a value into CV15 (assuming the Uhlenbrock's support this feature)?

[Martijn Meerts]

My Marklin ICE2 (factory fitted with decoder and interior lights) actually makes that noise as well, and it gets really loud when you turn the interior lights on =)

I have tried resetting the decoder a couple of times. It's annoying not being able to read CV's, because when you forget what you programmed into 1, you sort of have to reset the whole thing and start again .. I've gotten most things to work though, expect for 1 thing. Since it's not a MU train, rather than have the direction of the train determine which car has tail lights, I want to manually be able to turn them on and off. I thought I could just set it up so that F1 would activate tail lights in the front car, and F2 would activate tail lights in the rear car. That doesn't quite seem to work though. I had no problem programming them to F12 (just to test), so I might just have done something wrong.

[CaptOblivious]

My Marklin ICE2 (factory fitted with decoder and interior lights) actually makes that noise as well, and it gets really loud when you turn the interior lights on =)

I have tried resetting the decoder a couple of times. It's annoying not being able to read CV's, because when you forget what you programmed into 1, you sort of have to reset the whole thing and start again .. I've gotten most things to work though, expect for 1 thing. Since it's not a MU train, rather than have the direction of the train determine which car has tail lights, I want to manually be able to turn them on and off. I thought I could just set it up so that F1 would activate tail lights in the front car, and F2 would activate tail lights in the rear car. That doesn't quite seem to work though. I had no problem programming them to F12 (just to test), so I might just have done something wrong.

That's very odd, and annoying. Such should be straightforward, and I've done it with TCS and Digitrax decoders. I wonder: Would it be worth the effort to temporarily wire in a bulb to one of the functions, to see if the additional current draw would permit CV readback? Might the decoder be defective or damaged?

[Martijn Meerts]

I doubt the decoder is defective, otherwise all 4 of them would have to be defective =) Wiring in a lightbulb should do the trick, but not sure I want to do that. Might well be I did something wrong, or maybe the function outputs are reserved for something. If nothing else, I could switch to using outputs 3 and 4, they're by default set up to use F1 and F2.

I'll be ordering a couple of the Lokpilot FX micro decoders soon, which have Railcom. I can't say I've been impressed with Railcom so for, but the benefit is that it gives you a response whether or not programming the decoder was successful, even when using PoM.

[Martijn Meerts]

Lenz just announced that instead of a new function decoder (they discontinued the only function decoder they had a while ago), they're now adding the option to use the standard+ and silver mini+ as function decoders. All new decoders will get the bipolar option, at least, I think it'll be bipolar (it actually mentions in the description the outputs are direction dependent.. It pays to read the entire text ;)), they'll allow you to hook up lights to the motor output. And as an added extra, all current silver mini+ decoders with software version 7.x will get a free, downloadable software update. Of course, you'll need the Lenz decoder programmer to upload the update to the decoder, but hey ;)

Maybe this announcement is why it's taking so awfully long for my silver mini+ decoders to arrive, they've been on order for 3-4 weeks by now....