DCS Signal

Brandy,

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Which rail does the DCS signal run thru from the Tiu, I assume it's the center rail?

The short answer is the center rail. The actual answer is more complicated.

From The DCS O Gauge Companion 2nd Edition, page 56:

Home Run/Star Wiring Methods

While the 2-way communication between the DCS Remote and the TIU is done wirelessly, DCS provides 2-way communication between the TIU and PS2 engines through the rails. Although DCS has been proven to work very well using a number of different wiring schemes, it works best when there is a clear path for command and acknowledgement between the TIU and PS2 engines.

This clear path is best obtained when the wires for the center and outside rails are run as pairs. DCS uses a transmission method known as “differential signaling” to provide improved data communications through the rails between the TIU and PS2/PS3 engines. Differential signaling transmits information electrically with two complementary signals sent on two separate wires. In the case of DCS, these wires are the Hot and Common wires between the TIU and the tracks. These two wires provide "mirroring" of data packets which serves to make commands more easily identified by PS2 and PS3 engines.

While PS2/PS3 engines primarily receive commands through the center rail and respond to, or acknowledge, commands using the outside rails, in both instances the other rails not used provide the mirroring effect of differential signaling. To take best advantage of differential signaling, whenever possible Home Run or Star wiring should be implemented as described below using transformers, TIU channels, and terminal blocks. A terminal block is any device that will one accept of pair of wires as input and then splits that pair into several pairs of wires for output. It's a good idea to use only one terminal block for each TIU channel.

Is there any device to get a "Signal Strength" reading, other than via PS 2/3 locomotive back thru DCS hand controller?

No, there is not.

This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!

Concerning track signal.  I religiously follow Barry's 2nd Edition.  I have done the Home Run and Star wiring.  I clean my track with goo gone and re clean it with denatured alcohol.  I use Fastrack and check the joints.

When I recently purchased a PS-3 locomotive, I had a sound problems.  I have since done a signal test.  Over the layout track sections go from, Out of Range, from 3 to 10.  At first I thought it's the joints between sections track and the switches.

I have 2 blocks.  Probably 200' in one block 150' in the other.  It's a mix of run around, spurs and sidings.  Is there a way to make better signal contact so the signal will be more consistent.

When I recently purchased a PS-3 locomotive, I had a sound problems.  I have since done a signal test.  Over the layout track sections go from, Out of Range, from 3 to 10.

Some questions:

• What was the exact nature of your "sound problem" with the PS3 engine?
• What version of DCS are you using? 
• What model TIU do you have?
• Is this your only DCS engine? If not, does the low signal strength occur with other PS2 or PS3 engines?
• Does the problem go away if you tether the TIUI's Remote Input port to the base of the remote with a 4-conductor, curly, telephone handset cable?

I have 2 blocks.  Probably 200' in one block 150' in the other.

Do you mean loops with blocks within the loops, or do you really have only two blocks?

If you only have two blocks, they are way too long. How many separate track sections are in each block? It sounds as if you need to make more, shorter blocks, following the guidelines set out in The DCS O Gauge Companion 2nd Edition.

Try placing an 18 volt light bulb across each of the TIU's channel outputs, particularly if your TIU is not a Rev. L.

Barry:

1. The Extended Start up (SSU) & (SXW).

2. DCS 4.3.

3. Z-4000 to Rev L Fixed 1 & 2  with Loops, spurs, sidings.

    Z-1000 to Rev 13 Fixed 1 runs Roundhouse tracks and turntable.

4. The signal is the same for PS-2 engines and PS-3 engine.

5. Have  not tried it tethered.  I will try it.

6. Track sections are 10".30"straights 036,048,060,072 curves and switches.  Make up the 350' in the Fixed 1 & 2 Blocks

Barry:

I tried it tethered.  Little or nothing changed.  The only thing that was different.  The  remote tethered, the engine did not return to sound operation and I had to reset the feature reset.

Missabe,

   Part of your problem is because you did not adhere to the 12 track join discipline when building your DCS layout.  Barry is giving you a work around with the Magic lights, and it usually will work, and restore all 10's to your layout.  However by using 3' long sections instead of 12" individual track you can build a very long block still adhereing to the 12 track join discipline, and your signal will remain strong thru out most of the layout, then in certain far away places, you can add a few magic lights to maintain a complete 10 signal layout.   Good luck with your P3 stuff, at this point I have none.

PCRR/Dave

PCR:

I use Fastrack.  I do use  2 30"sections and up too 6 sections of various sizes and they end with Lionel lighted bumper.  I do not have these long yard tracks in blocks. Nor is the long Spur track.

Mainly I have 2 loops that are blocked.  That's were the problem occurs.  I have 2 terminal blocks, one for each loop.  I added lockons from the terminal in various parts of the loop.  It shows 18v when powered.

Missabe,

   Track power & DCS signal are not always the same, if you have violated the 12 join

discipline building rule you may still have a problem with the DCS signal.  The magic lights will usually help restore the required signal strength for great running.  I do have one other question, are you using single or multi strand wire, and what size wire are you using thru out your large layout, to help portray a proper DCS signal.

PCRR/Dave

PCR:

#16 AWG 1MM2 and some #14 AWG. stranded.  Some of it is from a company call Calterm 12 volt Primary Wire.

PCRR/Dave:

Are you saying the loop must be divided up into blocks?  I have to go, I very much appreciate your assistance.

Gerry

Brandy,

If you currently have 8-10 signal strength, then the best a Rev. L will do for you is get  to all 10's, although there are no guarantees. Signal strength over switch tracks is often problematical and not something over which you should lose a lot of sleep.

The only way to measure DCS signal strength is with a DCS engine. There are no shortcuts. Sounding the whistle as you move the engine around only indicates that the engine can receive and send DCS signals. It's not any kind of an indication of the actual strength of the DCS signal.

Gerry & Brandy,

    Both of you need to invest in Barry's DCS O Gauge Companion book and the OGR

Video Guide to DCS, and dive into the book, along with watching the video guide.  Although we can help you with individual problems you 2 must educate your selves as to the over all DCS engineering package, and how it works.

Gerry,

    Your 16 Gauge single strand wire maybe causing some of your signal strength problem.

Brandy,

  GG switches are famous for causing DCS signal problems, if you are getting 8-10 reading except thru your switches, you are doing fine, you might try a magic light

close to the switches, if you are loosing signal strength there.  The Rev L is not your problem, I run all 10's with mine on my FT layouts. 

PCRR/Dave

I have almost all Gargraves switches and do not have any signal problems, BUT, every switch is the end of 3 separately fed blocks, as I have severed the underswitch bus bars.

It was posted here years ago, that playing music thru the engine would show how well the DCS signal is doing because it uses a lot of the bandwidth (if I'm remembering correctly). (Jamie?)

 I forgot this until now. I will try my outdoor loop with some music and see how it does. I think if it distorts or gets cruddy, the signal is weaker.

I've had this happen in areas where the DCS signal is weaker. I'm pretty sure it is what caused the failure of the engine to complete the return to sound. I duplicated it in that exact area a second time. When I exited the signal test in a strong signal area, the engine sound returned without issue.

 That's all I have to go by. It may have been some other factor??

Joe,

Playing music through an engine to test the DCS signal is a lot like saying a book is a best seller because you liked it.

Music quality is completely subjective and what's acceptable varies from listener to listener. It's not a qualitative measurement of anything.

Sorry B!

that's what qualifies me as a sound technician!

(self taught)

Joe, I've always considered you to be sound.

Hey! An OGR member with a sense of humor!! All right!

Hey Pine Creek, I did buy the DCS Book, as well as, the down load copy. Anyway, you are correct, it is a very good book, but fooling with this Mobile 18X34 "O Gauge" layout, we've basically cut all of the center pins, and rewiring the whole **** thing. We had "NO" problems with Lionel TMCC/Legacy, until one of the new members who runs MTH Crap has the signal problems, so now we are reinventing the "Old Proverbial Wheel" to get him good signal strength, so he can his MTH Stuff. I guess that's what good club members do. I want to thank you folks once again for your help/advise....................Brandy!

PCRR/Dave:

If you read the post from the beginning you would see I have the downloaded edition of this book.

Any response from my last post.

What I am dealing with.

If you want to talk crap...then look at the crap that the New Jersey Hi-Railers are going thru to make Lionel TMCC/ Legacy work on that layout where DCS works fine!

Missabe,

   I do not know what MTH tech advised you that FasTrack could be part of your signal problem, however I have been running FasTrack sense DCS came on the market.  In the beginning I transitioned in and out of 711 & newer 072 an even some 022 Lionel switches.  The multi level layout in the Office & Game room, along with the smaller Christmas layouts ran with all 10's.  The Trick is to follow the 12 track join rule, and test as you build, if you need a magic light along certain parts of your track use it.

Most people run into trouble because they do not signal test as they build, and they violate the 12 track join rule.  Hate to disagree with the MTH Tech but I have never found FasTrack to be problem, and as you can see below a run on a serious bunch of older and newer FasTrack.   As far as retro-fitting a Legacy/TMCC layout with DCS, each one is different and has its own challenges, remember DCS should be tested as it is built for absolute best results, however there are lots of retro-fitted DCS layouts out there running perfectly.  The guys who like to bash DCS or TMCC/Legacy are usually the guys that engineering design skills are small and their mouth is large.  If you read Barry's book absorb his technical information and then apply the knowledge and test as you build you will have a great DCS, Legacy/TMCC combo layout that runs perfect.

If you violate the building principles & do no testing as you build, you will have problems. 

PCRR/Dave

On all 5 levels of FasTrack the DCS layout ran with almost perfect 10's, even with more than one train running on each level at the same time.  I see no way your signal problem has anything to due with Lionel FasTrack, unless you have damaged the track in some manner.

Missabe, my layour was built long before DCS, and uses a common ground buss running all around the layout  When DCS came out, I just plopped the TIUs between transformer and control panel and I have been running well ever since.  But, my layout was wired with 14-gauge stranded and, to get maximum control over my conventional engines running on the same "loop," was broken into some 70 individually-toggled blocks.  Every switch (but 2 of the 45) ends three blocks  So inadvertently I satisfied the rule on limiting track joints.

MY point is that you needn't do a rebuilding and complete rewiring.  Just sever the center rail in a few places and add more feeds, one to each block.  Don't sever outside rails, but do be sure there are enough ground drops.

PCRR/Dave,

I'm thinking of running new bus lines.  As I did in the first place.  Re:Star/Home Run as the book shows.  In essence, double up on the blocks and go to the problem sections of track.  Using 14 gauge solid wire  this time.

After reading and rereading the wiring section in the book.  Maybe I am not just comprehending.   Does the video show them actually doing the wiring?

PCRR/Dave'

I should waited for your reply. I will try what you said.

Missabe,

   Notice what RJR has pointed out to you, he recommends using the stranded wire for best signal results, not the solid wire, the 14 gauge is definitely a good engineering choice for DCS.  Where ever the 10-12 track section rule was violated a magic light was placed by the tracks, to regain max signal strength.  Also notice the (Magic Light) lighted Lionel lock ons, in front of almost every old Lionel 072 Switch, this insured proper signal at each switch location.  Further I was using the Rev L TIU at that time, and had magic lights at the beginning of each terminal Block.  The newer TIU's are better, and depending on the individual layout the magic lights can be eliminated almost completely.  In the OGR Video guide to DCS Rich goes over some proper wiring technology, but only shows the beginning transformer/TIU wiring to get the runner started, actual wiring in the video would have taken way to much video time, each layout being individually unique.

PCRR/Dave

Missabe;

To clarify on RJR's post;

When you cut the center rail to make blocks, you only want ONE power feed per block.

So if the center rail has power after you cut the it, go to the next section.

A cheap multimeter is a big help but any lighted car can be used to check for power on the center rail.

Multiple power connections in a block make multiple copies of the digital signal crossing each other,

That makes Tower of Babel time for electronics.

Russell is correct.  Sorry if I was not clear on this.

Dave, I like that picture you posted.  Shows I'm not the only one whose wire isn't perfectly colored and bundled

Yikes!

Yikes?

Just wondering how the electrons find their way out to the tracks.

Not only do they find their way to the tracks, but also back again, 60 times a second!  And DCS works well.

It takes a lot of wires when you have 70+toggled blocks and 45 switches.

It was just a joke...

Gentlemen,

   Russell makes a good point, it usually only takes one drop in each block to keep the DCS signal strong.  However as I indicated before test as you build, each individual layout is different, especially with different TIU revisions. 

RJR I like my pretty yellow wiring, messy or not.  Under the platform was actually a lot neater than on top.  Hay you had me beat, I only had 33 switches, lots were back to back also.  For this reason I have started to use FT 072 Command Control switches,

they eliminate so much of the switch wiring and also the AIU wiring.  MTH needs to engineer low voltage stand alone remote control switches of their own, similar to Lionel's Command Control FT switches. Massive engineering project no doubt about it.

It would be great to see them engineer a remote controls package that would work with all different manufacturers switches, controlled from the DCS hand held remote, would not hold my breath on this however.

PCRR/Dave

 What bulb number did you buy?

The bulb needs to have a decent draw (.2 or higher I think???)

to fix anything.

 Shouldn't need one on the "L" version.

Missabe, you can buy 18-volt bulbs on line quire cheaply:  #1885 or #1887.

Why not use the Susan Deats DCS filters?  They don't consume power and perform the same function.

Engineer-Joe & PCRR/Dave,

Joe the # on the bulb is 757.

Concerning my block wiring.  I daisy chained the individual block. To get a 18v reading on the entire layout.  If the layout was a circle the block wire started at 6 and daisy chain from there to 9-12-3 on the clock.

So the center rail should be cut at 9-12-3?  And if 28v or a 18v bulb should be placed at the end of the switch.  As in Dave's picture.