DCS signals!

Jeff,

Unlike TMCC which is a radio signal that follows the outside rail, I believe that DCS is carried by the power itself (power line carrier).

This means that the center rail, and at least one outside rail that is continuously electrically connected around the layout, are needed.  These are the very same rails that would already carry power to the locomotive.  They also carry the DCS signal.

Mike

Thank you for YOUR reply. I was thinking the system had to use two of the rails. That answers my question.

@Jeff B. Haertlein posted:

Thank you for YOUR reply. I was thinking the system had to use two of the rails. That answers my question.

......and Jeff.......for more reliability I  solder wires connecting the two outside rails on seperate pieces of track.          I usually keep that center rail really clean for the signal from the DCS / TIU.   

I'm still trying to figure out if the NO-OX  product discussed on the Forum will be a good product for the center rail.

  I have to be cautious about anything that might be used on the two outside rails since  I mostly run engines with rubber type traction tires.

Good luck ......have fun .

Always make sure you have good batteries in remote, DCS needs good ground (outside rails) and third rail. Also check the battery in locomotive if equipped. Is everything on the same operating version? Dirty locomotive wheels don't help  either. Check all electrical connections for track. Does this happen in all locations or just one.

These are some of the things I check

Mike is correct.

When you press a button on the remote, it sends a wireless signal through the air to the TIU to execute that command. The TIU then sends a signal (data packet) to the engine via the center rail to execute that command. Because DCS is a two-way system, the engine then sends an acknowledgement of that command signal back to the TIU via the outside rail. Finally, the TIU sends an acknowledgement back to the remote. 

So, the system uses both a center and an outside rail.

@Richie C. posted:

Mike is correct.

When you press a button on the remote, it sends a wireless signal through the air to the TIU to execute that command. The TIU then sends a signal (data packet) to the engine via the center rail to execute that command. Because DCS is a two-way system, the engine then sends an acknowledgement of that command signal back to the TIU via the outside rail. Finally, the TIU sends an acknowledgement back to the remote.

So, the system uses both a center and an outside rail.

Actually, this is not entirely correct.  The track is basically a half-duplex transmission line.  The outgoing signals and the incoming signals require two conductors to function.  The TIU sends commands out using both the outside and center rails, the locomotives responds using the same rails.

Thank you for the replies thus far. All my wiring is soldered to the rails. And every other section of Gargraves track has the ground alternated. I am using a buss system, and my test of the system was in the higher numbers. I know caution regarding a buss system lurks, but then some people mention it is OK. What still gets me is this example. I can run an engine PS-2 or PS3 upgrades, on my mainlines. Power them down and many times try to read the engines and find they are not on the track, which they obviously are. Sometimes several days may go by and sometimes the system will read an engine and it finds it once again. Right now I have three engines stalled on my two loops. One engine is constantly found, while the other two on the inner loop are not found. I can usually power up as conventional under certain circumstances. If that happens I can bring the engine out and about. Power down. Power up and read and the engine is found. Right now, I am going back to the easiest solution first. CLEAN my trackage. Also my DCS is the same version as I bought it as a set. Thanks everybody!!

If you are not consistently getting at least 9's and 10's for track signals around the layout, you will likely have issues bringing up engines.  I don't know what you mean by "higher numbers".

As I recall John, there is a scale and my tests were 7 or 8, and I will have to do a diagnostic test soon to see what I am getting.

@Jeff B. Haertlein posted:

As I recall John, there is a scale and my tests were 7 or 8, and I will have to do a diagnostic test soon to see what I am getting.

That's not good. You need 9-10. Anything lower than that and you'll have issues. You mentioned your layout is buss wired. That isn't helping the signal.

Every layout is unique, and I've seen layouts that seem to have perfect signals but had spotty results in adding and finding engines.  I've also seen layouts that have what looks like lousy numbers, but for the most part everything runs very well.

My statement about 9's and 10's is a general guideline, I believe Dave Hikel had posted a document that showed how the signal test interpreted the signals to indicate the signal strength.  As I recall, you could get 10's even though you were dropping packets, so it's pretty "loosey goosey" as to exactly how good the track signal is.  I know I've seen more than one instance where an engine was getting 10's and still couldn't be found when they powered up.  When they finally got the engine running, parking it on exactly the same spot as it was not found yielded solid 10's every time.

OK,  I guess I will have to do some serious re-wiring in the future.  I will be off the computer now until tonight. Thanks again for all your help and insights!!

@gunrunnerjohn posted:

Actually, this is not entirely correct.  The track is basically a half-duplex transmission line.  The outgoing signals and the incoming signals require two conductors to function.  The TIU sends commands out using both the outside and center rails, the locomotives responds using the same rails.

You may be right - just repeating for the OP what is in Barry's book, which seems to indicate out on center rail and back on outside rail. Perhaps that's an oversimplification of what occurs.

I think Barry was trying to make it somewhat "logical" for the novice, but it's really not how the signals actually are propagated.   Perhaps I should take my EE hat off and try to simplify it, but I like to actually use facts if I can.

@Jeff B. Haertlein posted:

Thank you for the replies thus far. All my wiring is soldered to the rails. And every other section of Gargraves track has the ground alternated. I am using a buss system, and my test of the system was in the higher numbers. I know caution regarding a buss system lurks, but then some people mention it is OK. What still gets me is this example. I can run an engine PS-2 or PS3 upgrades, on my mainlines. Power them down and many times try to read the engines and find they are not on the track, which they obviously are. Sometimes several days may go by and sometimes the system will read an engine and it finds it once again. Right now I have three engines stalled on my two loops. One engine is constantly found, while the other two on the inner loop are not found. I can usually power up as conventional under certain circumstances. If that happens I can bring the engine out and about. Power down. Power up and read and the engine is found. Right now, I am going back to the easiest solution first. CLEAN my trackage. Also my DCS is the same version as I bought it as a set. Thanks everybody!!

are the buss sections of the layout fully isolated? If not, try cutting a section (electrically) and see if the signal improves.

In other words, the signal should not repeat on itself, or have more than one path to an engine. So track sections should be separated in at least one spot in a loop.

Your varying degree of success may just be luck on where things get parked. Remove any TMCC or other powered equipment.

Try connecting your DCS system to just a straight section of track and see what the signal strength is. That will assure the system is working properly.

Something nobody asked was what version TIU do you have?  A rev L has a stronger dcs signal but they sometimes have an issue that reduces the strength. If you're not using all of the tiu channels, you might switch channels to see if things improve. If an earlier rev tiu, you might want to add a light bulb or filter to your power output.

As for channels, I am not sure what you mean exactly. My TIU that I am using is hooked up to the fixed voltages in and out 1 and 2, 1 and 2 are used for my two loops of trackage and these loops are insulated by my #8 Ross crossover. So I power up my MTH 4000 to 17-18 volts for the two controls on the transformer.

Like he said, what rev of the TIU do you have, look at the label on the bottom?  Also, what version of software is the TIU running?

Here's where I am once again ignorant on understanding all this. First off I have rev1 Now for the question of what soft ware....I don't know.

I also must ask regarding the pilot light on the TIU. If I power up my Z4000. First I turn up the left side handle, and the pilot light turns on. If I would just turn up the right hand throttle, the light does not light.

Jeff, I’m not going to dispute the recommended paired wiring method and 1 paired wire to each block. My layout sounds something like yours with the common ground buss wiring method. Every 3 foot section of Gargraves has a center rail drop and I alternated the outside rails every section. Every leg of every turnout has it’s own drop. Large layout with 2 TIU’s. It is blocked. Long single mainline with 4 blocks. Plus numerous yard tracks. I’ve run DCS from the get go. The first month was cleaning up wiring and removing toggle switches. With clean track and pickup rollers it pretty much yields a 10 everywhere. Engines can be placed on the layout wherever and they still add. I wasn’t about to rip up and rewire a large layout.

Just curious as to what your using as far as buss wiring. I used either a 10 or 12 gauge buss with 14 gauge feeders. Every leg of the Ross Turnouts has an 18 gauge feeder. Way over wired according to the book and it shouldn’t work. But it does. I’ve always believed the reason mine ran well was the robust wiring. It was built before LED’s were the norm, back in the day when one train could draw close to 10 amps or more.

I was a friend of Marty Fitzhenry. Marty was a perfectionist when it came to how is layout ran. I never saw a blip or a hiccup when seeing it run. Large layout. 1 TIU and Buss wiring with a common ground. He also had countless toggle switches. He was a beta tester for DCS before it was available. It didn’t work as advertised at first. Marty was the founder of the Magic Lightbulb.

OK, I googled software for the TIU and found a post from 2013 and it mentioned when you turn on the remote it will tell you what version. So I just did so and it said version 6!