[solved] how to generate Railsync signal from DCC signal

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[solved] how to generate Railsync signal from DCC signal

Postby skippa » 16.06.2013, 10:39

Hi everybody,

I'am still on the quest of running a loconet/dcc layout without any kind of central station. Just for clarification since there are several threads available describing stand alone loconet with regular power supply on railsync/seperate booster branches: I want to build up a proper Loconet (fremo-style) that can also supply several boosters along the layout without seperate wiring.

DCC signal generation from rocrail/ddl works fine as well as standalone loconet using a MGV101 (or MGV85) with a "regular" power supply on the Railsync lines.
My understanding ist the only piece missing ist to feed in the DCC signal into the railsync and thus converting it from 12V+ to +-6V opposite phase signals.

Can anyone help me out drawing up an electronics schematic and indicating the needed parts? It is signal (2) to (3) in the sketch.

Thank you,
Jens

Image
Last edited by skippa on 30.11.2013, 16:49, edited 1 time in total.
skippa
 

Postby RainerK » 17.06.2013, 06:02

Hi Jens,

the standard voltage at RailSync is the same as rails. (+-6V is really not enough)
Usually the rail output of the CS will be connected direct only to RailSync instead of rails
and then the inputs of all booster are connected to RailSync.
Please note, You need the same type of boosters for all and they must able to operate with rail voltage on its inputs.
Minimal requirement is the same principal schematic and the same voltage on outputs for all.
Best recommendation is ORD-3.

[edit]
A unit to convert "asym2sym DCC" is the ORD-5 by Peter Giling (unfortunately the link is found only on the ORD-3 page).
Its normaly for DCC over USB2seriell, but "asym2sym" DCC presents the same problem/solution.

To limit the current in case of shortcircuits on RailSync there are some recommendations to found in the web.
Between CS and RailSync two resistors (22 or 27 Ω / 1,5 W) should be serial connected into both lines.
[/edit]

Best Regards
RainerK
Best Regards, es grüßt RainerK

DCC++ with Arduino Uno / Motor shield and LocoNet GCA85, 50, 93 and 136. Special interests: DIY electronic assemblies. http://www.rainermoba.blogspot.com
Planning replace the coincidence by the mistake
RainerK
 

Postby skippa » 19.06.2013, 20:59

Hi Rainer

the standard voltage at RailSync is the same as rails. (+-6V is really not enough)
Usually the rail output of the CS will be connected direct only to RailSync instead of rails
and then the inputs of all booster are connected to RailSync.

That is exactly what I am intending: feed in the DCC signal as RailSync. This is then amplified with one or more boosters and only then fed into the rails.

My understanding is that the original 14V DCC signal (versus ground) is split into two counterphase with +7V and -7V (both versus ground). That is at least what is described in the Digitrax manuals e.g. in http://www.dccwiki.com/LocoNet#The_Digitrax_RJ12_LocoNet_Wiring_Standard.

My understanding is further that from then on, a multiple of boosters can be supplied with the signal, connected through loconet ("chained together"). Preferrably but not necessarily same booster type, as long as output voltage is the same and electrical isolation of Rails to loconet is given through optocoupling. This is how FREMO runs it, isn't it?

As for the ORD-5, it reads as if it is indeed converting the single phase ddx signal into something "as generated from any other central station". Unfortunately, doesn't mention what that means.
It seems to me that I can feed the RS232 ddx signal (step 1 on the sketch) directly into the ORD5 an aquire my counterphased RailSnyc signal (step 3 on the sketch)? Voltage would be depending on power supply on the power input J3. This saves the Booster (M* Delta in the sketch above), doesn't it? Input would be the J1/RS232 and output the St1/Rj12/Loconet connector, right?
Questions over questions and the answer must be "no" since the ORD5 does not have the GND pins connected at the St1/RJ12/Loconet connector.

<confused>

Jens
skippa
 

Postby RainerK » 20.06.2013, 06:27

Hi Jens,

My understanding is that the original 14V DCC signal (versus ground) is split into two counterphase with +7V and -7V (both versus ground). That is at least what is described in the Digitrax manuals e.g. in http://www.dccwiki.com/LocoNet#The_Digi ... g_Standard.
right
My understanding is further that from then on, a multiple of boosters can be supplied with the signal, connected through loconet ("chained together"). Preferrably but not necessarily same booster type, as long as output voltage is the same and electrical isolation of Rails to loconet is given through optocoupling. This is how FREMO runs it, isn't it?
right
As for the ORD-5, it reads as if it is indeed converting the single phase ddx signal into something "as generated from any other central station". Unfortunately, doesn't mention what that means.
simply it means that the ORD-5 output is functional the same as CS with symmetrical rail output like DIGITRAX DB150 instead asymmetrical like DELTA 6604/66045 etc.
It seems to me that I can feed the RS232 ddx signal (step 1 on the sketch) directly into the ORD5 an aquire my counterphased RailSnyc signal (step 3 on the sketch)?
right
Voltage would be depending on power supply on the power input J3. This saves the Booster (M* Delta in the sketch above), doesn't it?
right
Questions over questions and the answer must be "no" since the ORD5 does not have the GND pins connected at the St1/RJ12/Loconet connector.
Thats not a contradiction, since the input of an opto isolated booster use not GND but only the polarity changes between the two RailSync lines.
Please look at the attached circuit section of ORD-3.
There are 2 optocouplers, one for every polarity of input signal from RailSync.
There is not a connection to GND :!:
The reason why the ORD-5 also doesn't need it :!:

If You will use a FRED etc. on the Loconet and the supply is necessary, then it make sense to connect GND from ORD-5 to Pin 2/5 of the LocoNet-connector.
Then the ORD-5 must supplied with its own transformer :!:

I hope all questions now answered.

Best Regards
RainerK
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Best Regards, es grüßt RainerK

DCC++ with Arduino Uno / Motor shield and LocoNet GCA85, 50, 93 and 136. Special interests: DIY electronic assemblies. http://www.rainermoba.blogspot.com
Planning replace the coincidence by the mistake
RainerK
 

Postby skippa » 20.06.2013, 22:10

Questions over questions and the answer must be "no" since the ORD5 does not have the GND pins connected at the St1/RJ12/Loconet connector.
Thats not a contradiction, since the input of an opto isolated booster use not GND but only the polarity changes between the two RailSync lines.
Please look at the attached circuit section of ORD-3.
There are 2 optocouplers, one for every polarity of input signal from RailSync.
There is not a connection to GND :!:
The reason why the ORD-5 also doesn't need it :!:

I think I understand. Good point. I just wonder why the ORD5 is never mentioned somewhere in the ddx/dcc232 section.

If You will use a FRED etc. on the Loconet and the supply is necessary, then it make sense to connect GND from ORD-5 to Pin 2/5 of the LocoNet-connector.
Then the ORD-5 must supplied with its own transformer :!:

okay, it will get it's transformer.
I assume its o.k. to then to connect GND (below C3) in the schematics http://wiki.rocrail.net/lib/exe/fetch.php?id=ord5-en&cache=cache&media=mgv:hardware:ord-5-sch.pdf with pin 2/5 on St1?

I hope all questions now answered.

I am sure there will be more but I think I have made a huge step forward allready. And I am also allready in contact with Peter about getting an ORD5 ;-)

Thank you!
Jens
skippa
 

Postby RainerK » 21.06.2013, 05:35

Hi Jens,
I assume its o.k. to then to connect GND (below C3) in the schematics http://wiki.rocrail.net/lib/exe/fetch.p ... -5-sch.pdf with pin 2/5 on St1?
Yes, but note, its only necessary if You will use a unit like FRED etc. and supply it with RailSync power.

For more questions You're welcome and contact with Peter is ever a good idea. :thumb_up:

Best Regards
RainerK
Best Regards, es grüßt RainerK

DCC++ with Arduino Uno / Motor shield and LocoNet GCA85, 50, 93 and 136. Special interests: DIY electronic assemblies. http://www.rainermoba.blogspot.com
Planning replace the coincidence by the mistake
RainerK
 

Postby Buddace » 25.06.2013, 22:04

My personal idea....around internet there are a lot of different and opposite discussion/opinion about loconet PE; worst talk about loconet patent refer only transponding and not Loconet. So may be good idea for Digitrax evaluate free donation to use Loconet PE for non commercial developer...
I tell some time my problem...I don't share code because some idiot try to stole code for commercial use....
www.dccworld.com First and Only Italian DCC Website.

TMWDCC/TBX , zDCC, Lokmaus 2, Arnold DCC, Intellibox, Hornby Select, A lot of Loconet DIY (Loconet SwitcBoard, Loconet P50, etc..)
Buddace
 

Postby RainerK » 26.06.2013, 05:36

Hi Buddace,

the "loconet PE and other items of licence etc." is not the theme of this thread.
Here we have only treated technical aspects of "RailSync" .

IMHO You mean this thread:
http://forum.rocrail.net/viewtopic.php?t=6018 but it's [solved].

Best Regards
RainerK
Best Regards, es grüßt RainerK

DCC++ with Arduino Uno / Motor shield and LocoNet GCA85, 50, 93 and 136. Special interests: DIY electronic assemblies. http://www.rainermoba.blogspot.com
Planning replace the coincidence by the mistake
RainerK
 

Postby skippa » 22.07.2013, 21:52

Hi Rainer et al,

I have made some progress: obtained ORD5 and built it. Put together some components, added loconet plug to the Tams B4 Booster.

Added Rasperry Pi and built it to use Rocrail. Built empty example layout. Tested ddx via usb ok on original layout (interfacing on a Märklin Delta...)

This is how it looks like.
Image

Now comes my trouble:
I am reasonably sure that the Raspi generates the signal, since I tested it on my home layout.
I can switch on and off voltage on the railsync lines in the RJ12 on the ORD5. I am using a Märklin power supply, rated 16V~ and 32VA to power the ORD5. I am measuring 6V between each of the railsync lines vs. GND and 6V railsync A vs. B.
Seems ok to me.
I added the Tams B4 Booster. With railsync power of it shows "no signal" (no surprise). Switch on power Booster LED shows "signal". This state, I do have about 10V power on the line. Again, I am using another Märklin power supply, rated 16V~ and 32VA to power the Booster.
But: I can not bring a loco to life and I also can not enter the programming mode for the booster. Simply no reaction.
Also no reaction when I switch of DCC power again, LED still shows signal.
My suspicion is that voltage level for the boster is not sufficient since there are only this 10V on the line. Unfortunately, I have no idea to what nominal power the booster is currently set to. Also, I do not have other power supplies available.

Any ideas on this?

Thanks,
Jens
skippa
 

Postby RainerK » 23.07.2013, 05:56

Hi Jens,

without any qualified measuring of amplitudes and in the time domain no one can help You.
Sorry, but I see no other way to fix the problem, there are too many points that could be the reason.
Please contact a friend near of You who has an oscilloscop and some experience with it.
That will bring You a big step further.

Best Regards
RainerK
Best Regards, es grüßt RainerK

DCC++ with Arduino Uno / Motor shield and LocoNet GCA85, 50, 93 and 136. Special interests: DIY electronic assemblies. http://www.rainermoba.blogspot.com
Planning replace the coincidence by the mistake
RainerK
 

Postby skippa » 19.10.2013, 10:59

Hi,

unfortunately, I don't have sufficient equipment to measure time domain.
So I am reliying on testing. I have made some progress, but it still leaves some questions.

fully working: Raspi (rocrail+ddl) - usb2serial - booster - loco
-> Signal generated by Raspi sems to be ok

also fully working: Desktop Computer RS232 (rocrail + ddl) - Ord5 (with 16V~power supply) - booster (with another 16V~ power supply) - loco
-> Ord5, Booster and cableling seems to be ok

NOT working:
Raspi (rocarail + ddl) - usb2serial - Ord5 (with 16V~power supply) - booster (with another 16V~ power supply) - loco

I really don't get it. Any ideas?

Best,
Jens
skippa
 

Postby skippa » 30.11.2013, 16:48

Hello,

fyi: I have made it.

I used the approach as described above. The ORD5 will generate the railsync signal from the DCC.
The reason why it was not working is acutally the choice of the usb2serial converter. I have tried three "sticks" and two cables. Interestingly, the pure generation of the DCC worked with any of these, just not the conversation to railsync. The usb2serial cable working is a Delock without the LEDs in the plug.
lsbusb for this cable:
Bus 001 Device 004: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port

rocrail.ini's relevant chapters
<digint iid="ddx@stellwerkPi" lib="ddx" stress="false" libpath="/opt/rocrail">
<ddx port="/dev/ttyUSB0" portbase="0x20201000" s88port="0" s88busses="1" s88b0modcnt="0" s88b1modcnt="0" s88b2modcnt="0" s88b3modcnt="0" shortcutdelay="1000" shortcutchecking="false" inversedsr="false" dcc="true" motorolarefresh="false" motorola="false" queuecheck="false" fastcvget="false" mmlongpause="false"/>
</digint>


Best,

Jens
skippa
 


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