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I'm working on coming up with a solution for some yard track at our club, we have several sets of tracks that we'd like to get DCS working on.  We have a rotary switch to select one of "n" tracks to power at a time, so I came up with this scheme.

We will be using a separate TIU channel for this task, and it'll be used in passive mode.  The yard power comes through a high-current 22uh choke to avoid any issues with crosstalk with the DCS signal on the mainline.  Operation is as follows.

Starting with the Track Selector off, no power to the TIU channel or tracks.  Switch is rotated to the correct track, the relay is energized, and that track is connected to the TIU channel output.  This results in the DCS signal becoming active and emitting the watchdog.  The plan is to keep the engine silent until it's started up.

See any issue with the idea?  Got any suggestions to improve on it?

Switch Yard DCS Signal Manager

 The final solution, forget the stuff above!

This is the what we finally came up with.  It's a small add-in board to a DCS Remote Commander that turns the DCS-RC into a continuous watchdog generator.  It plugs into some pins we add to the PCB.

DCS-RC Watchdog Reset Generator Thru-Hole Gerber Files.zip

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Last edited by gunrunnerjohn
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John, before DCS was released I had that problem while learning the system.  I have my big yard with 23 tracks and my turntable with 40 tracks.   On my big yard each track was controlled with toggle switches.  On the 40 tracks at the turntable, control was done with rotary switches.  I ended up adding a common buss wire to all track grounds.  I immediately got a 10 signal.  I have that same 10 signal today.  People have had success with lighted bumpers.  As we know, yard tracks and sidings can be tricky.  I know Barry has lighted bumpers and has success with them.  Being a toy train guy, I love the look of the postwar red lighted bumper.  I may put them on yet and wire the center rail contact from another power source.  I was thinking a rail cut in front of the bumper and wire the end of the track with wires soldered to them.  The look of 23 lighted bumpers will please this toy train guy.

Last edited by Marty Fitzhenry

John,

There's a non-wiring method to having any MTH engine (or lashup!) come up dark and silent on any powered track after the watchdog signal has come and gone.

From page 105 of The DCS Companion 3rd Edition:

If a lashup is powered on after the watchdog signal has come and gone, perhaps if its siding was toggled on after voltage appeared at the TIU channel outputs connected to its siding, there are two ways to put the lashup into DCS mode. One way to put the lashup into DCS mode is to turn off power to the inputs for the TIU channel that is connected to the track upon which the lashup resides, toggle on the siding and then re-apply power. The other way is to first highlight the lashup in the remote's Active or Inactive Engine list. Then, flip the toggle switch and immediately press the thumbwheel to select the lashup. It will come up in DCS stealth mode, dark and silent. This also works with individual DCS engines.

 


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Barry Broskowitz posted:
The other way is to first highlight the lashup in the remote's Active or Inactive Engine list. Then, flip the toggle switch and immediately press the thumbwheel to select the lashup. It will come up in DCS stealth mode, dark and silent. This also works with individual DCS engines.

Some of the club members are barely able to run the engines using DCS, I don't think a little rain-dance of synchronizing the power on the tracks and the remote is going to fly.  For about $3 in parts, I can make this appear seamless without any special knowledge by the users.

rtr12 posted:

Isn't passive mode connecting to the output only? I was thinking (probably incorrectly?) that the TIU had to see power on the input before it would send the DCS signal? I have never tried passive mode or super TIU mode either for that matter.

Works fine when the voltage is on the output, try it.

 Barry Broskowitz posted:

John,

Whatever.

It's not "rocket science", it costs nothing and it takes no particular skill to implement. To me, that's the definition of a good solution.

 That's your definition of a good solution. 

Pretty presumptuous of you to assume that you know better what will work for us in our situation.  Operationally, people that come in on visitor's days will find it much easier to live with my solution, it doesn't take any extra knowledge or extra keystrokes and synchronization.  They just turn on the track they're staged on and start up and drive out.  To me, that's the definition of a good solution.  Since I get to define the solution for my circumstances, that happens to be the definition of a good solution in this case.

Last edited by gunrunnerjohn
gunrunnerjohn posted:

...

We will be using a separate TIU channel for this task, and it'll be used in passive mode.  The yard power comes through a high-current 22uh choke to avoid any issues with crosstalk with the DCS signal on the mainline. 

If the 22uH is to the left of the diagram (off the page) wouldn't the relay capacitor degrade the DCS signal on the selected track?

If I understand the operation, when changing from one track to another, the user must first rotate back to the "OFF" position.  And when selecting the new track, the user must rotate the knob to the desired position within whatever the interval (a few seconds?) during which the TIU sends the watchdog after power up. 

And if lighted passenger cars are on a siding, they will briefly flash as the rotary passes by.

Does the typical individual toggle switch approach present a space issue?

As discussed in the contemporaneous thread about the DCS watchdog using rotary switch for turntable power, in some situations it can make sense to add complexity to make it simple for the end-user.

OK, understood we're talking about an add-on.

So is there a visual indicator of which siding has power?  Lighted bumper, control panel LED, etc?

I'm still curious about having to first return to the "OFF" position when changing active track.   The club guys will learn by experience but I'm thinking about your visitor day scenario.  The approach in the other thread uses a relay-per-track which is not a drop-in mod for your configuration.  But what about "automating" just that single relay that toggles power to the passive-mode TIU output?  In other words whenever and while the rotary changes position, it disables the relay and then re-enables it after the rotary has settled on the new position.  I'm not saying it's a simple circuit but more in the spirit of a discussion about dealing with what appears to be more than a one-off.

Yep, each yard track has a lighted bumper at the end.  I thought about a more exotic solution, but in the end simplicity won out in my thinking.

Right now I'm looking at a handful of diodes, a choke, a capacitor, a resistor, and the relay.  In addition, I don't have to hack any of the existing wiring, just tap into it.  I'll be able to assemble this all on a small board and just stick it under the layout at the control panel where all that wiring is already available.

I can visualize how your solution would work, but it would be more work.  I believe I'd also have to hold off the power to the track as well as the TIU channel. A brief power interruption of the TIU channel probably wouldn't be enough to trigger the watchdog output.  I'd also have to add some logic to know when the switch transitions take place to control the action.  Not difficult, just more parts, and more work.

John,

That's your definition of a good solution. 

Yes, it was. Be careful when you scratch an itch - you'll make that thin skin of yours bleed all over the place.

Regardless, have you thought about just hooking up a DCS Remote Commander in Passive mode so that when you select a siding with your selector switch, the DCS Commander receiver emits the watchdog signal?

The receiver is less expensive than a TIU and, unlike the TIU, there's no Aux. Power requirement. This solution should be just as simple as yours only less expensive and a bit less work to implement.

BTW, it's on page 206 of The DCS Companion 3rd Edition.


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Last edited by Barry Broskowitz

This is an "ignore the man behind the curtain" situation. 

If you accept the procedure of rotating the switch to the "OFF" position for a few seconds every time you want to change the active siding then so be it.  A possible benefit of Barry's suggestion to use the DCSRC would be have your lighted bumpers remain on while the man-behind-the-curtain (i.e., the DCSRC) is momentary attached to the yard power for the purpose of generating the watchdog to silence the new track.  Otherwise the lighted bumper on the new active track would turn off during the interval when power is removed from TIU.  I'm not sure that's what Barry had in mind but I figure he was proposing the DCSRC in addition to the existing passive-mode TIU which you'd obviously need to control your engines.

Anyway, I guess simplicity wins out.  I was thinking it could be done with a bunch of capacitors to detect a change in the switch position and a 555-timer chip to detach the relay for a couple seconds to cycle power to the passive TIU.  But during this interval the lighted bumper would turn off which could be confusing to the casual user if the lighted bumper is the only indicator of the active siding.

As always, I'm here to save the day with more complex solutions!  How about that relay board- arduino combo from the other thread?  I'm unsure of your exact set-up, but if it would be useful to ever have more than one of the side tracks turned on at the same time, I would go with the remote commander to produce a watchdog signal.   In either case, one relay on the board can be used to turn on and off the remote commander, or input to the TIU, and the rest to supply power to the sidings.  

A simple sketch on an arduino could be programed to cycle TIU/Remote Commander on and off every time a new siding is switched on.  It's, of course, more complex than your solution, GRJ, but it would allow switching between tracks without having to go back to zero every time.  


As a side note, perhaps those that can bend the right ears at MTH might consider suggesting a firmware update that would allow some signal to be sent in on the serial port that tells the TIU to send out a watchdog signal.   Perhaps even as an add-on box that plugs into the TIU and has an input side so that whenever the input is turned off then on again the TIU would broadcast the watchdog.  this would solve everyone's problems with switched sidings, and I'm somewhat surprised that some method for users to trigger a watchdog without reseting a channel was not added years ago.  

JGL

stan2004 posted:
I'm not sure that's what Barry had in mind but I figure he was proposing the DCSRC in addition to the existing passive-mode TIU which you'd obviously need to control your engines.

That's the only way I could see it working, and I can't see having another box in the picture when I have one that is perfectly capable of generating a watchdog.

stan2004 posted:
Anyway, I guess simplicity wins out.  I was thinking it could be done with a bunch of capacitors to detect a change in the switch position and a 555-timer chip to detach the relay for a couple seconds to cycle power to the passive TIU.  But during this interval the lighted bumper would turn off which could be confusing to the casual user if the lighted bumper is the only indicator of the active siding.

I think in this case, I'll go with simplicity.  If they can't live with turning off the sidings when starting up a DCS locomotive, they'll have to add it while it's idling on the tracks.

JohnGaltLine posted:

As always, I'm here to save the day with more complex solutions!

We could debate the "saving the day" part...

JohnGaltLine posted:

As always, I'm here to save the day with more complex solutions!  How about that relay board- arduino combo from the other thread?  I'm unsure of your exact set-up, but if it would be useful to ever have more than one of the side tracks turned on at the same time, I would go with the remote commander to produce a watchdog signal.   In either case, one relay on the board can be used to turn on and off the remote commander, or input to the TIU, and the rest to supply power to the sidings.  

L

Yikes!  Introducing that much extra work isn't in my game plan!  You obviously missed my signature line!

Nothing is so easy as the job you imagine someone else doing.

JohnGaltLine posted:
As a side note, perhaps those that can bend the right ears at MTH might consider suggesting a firmware update that would allow some signal to be sent in on the serial port that tells the TIU to send out a watchdog signal.   Perhaps even as an add-on box that plugs into the TIU and has an input side so that whenever the input is turned off then on again the TIU would broadcast the watchdog.  this would solve everyone's problems with switched sidings, and I'm somewhat surprised that some method for users to trigger a watchdog without reseting a channel was not added years ago.

Can't argue that would be useful for a lot of folks, but I don't see it happening any time soon.  Maybe this is a product idea.

Remember that you did ask for suggestions!

In the "other" thread, PLCProf proposed a touch-sensor detector or something like that to momentarily activate the relay whenever someone hand touched the control knob.  That would involve some circuitry so I guess it was voted off the island.  But remember the QSI motion sensor for the cattle-car sound cars?  It was a simple but ingenious idea to detect motion.

Untitled

If something like that could be attached to the shaft or any moving part of the rotary switch, it could trigger a timer (homebrew 555 or a $1-2 eBay module ) which would momentarily drive the new relay to remove track power from the passive-TIU.

It would be a simple job since I am indeed imagining you doing it. 

 

 

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Last edited by stan2004

John,

Sure, envision connecting two DCS channels to the same track, that's crosstalk.

No, not at all.

You would use the TIU channel that powers the mainline to which the sidings connect as your "Yard Power". As soon as the connection is made, the engine gets a watchdog from the DCSRC receiver and then is controlled from the DCS Remote using the TIU channel of the main line.

Barry Broskowitz posted:

John,

The DSCRC receiver simply replaces the passive mode TIU channel, without the need for an Aux. Power connection.

If the passive mode TIU channel works, then the DCSRC receiver will work, as well.

Really?  So I can use the DCS remote with the DCSRC?  I'll bet that's news to MTH.

Remember, I'm using the TIU already to provide DCS to the tracks.  The TIU does just a bit more than the DCSRC, which won't work in my scenario.

As far as using the mainline signal in the yard, we've already tried that, and the signal isn't sufficient to offer reliable running.

Last edited by gunrunnerjohn

John,

Really?  So I can use the DCS remote with the DCSRC?  I'll bet that's news to MTH.

The two interoperate, connected to the same tracks, absolutely perfectly without any issues at all.

I'm using the TIU already to provide DCS to the tracks.  The TIU does just a bit more than the DCSRC, which won't work in my scenario.

The DCSRC receiver replaces the additional TIU that you're using in your solution, but only to generate a watchdog signal. The mainline TIU (or some other TIU already own the layout) is what would provide the ability to control the engines.

As far as using the mainline signal in the yard, we've already tried that, and the signal isn't sufficient to offer reliable running.

I'd suggest that tweaking the layout a bit to improve the DCS signal distribution could make using the DCSRC receiver and the mainline TIU work just fine as a solution. Regardless, assuming that you're operating in  Super TIU mode, you could use any channel on any TIU that has available extra DCS signal capacity. You don't need much DCS capacity, only enough to handle a single siding at a time.

Regardless, rest assured that there is absolutely no difficulty or operational issue with connecting a DCSRC receiver to the same track as a TIU channel, and even with each operating engines simultaneously. Been there, done that and got the T-shirt.  

Anyways, use my solution or not. I offer it in the spirit of assistance. Good luck whatever direction you choose.

Last edited by Barry Broskowitz

Here's the fix.... Assign a shop  foreman (experienced dcs user)  with his own remote who get the engines ready to leave the shop on the outbound shop track.  He now  hands over the engine to a club member .  ID  to same ID.  He's also responsible for putting engine away when  they arrive.  

Barry where do you  get the T-shirt?

gunrunnerjohn posted:

Sure, envision connecting two DCS channels to the same track, that's crosstalk.  That happens as you cross channel boundaries, but having them connected all the time would play havoc with the DCS signals.  The 22uh chokes are to prevent that from happening.  Since one ZW is powering all the yards I'm working on, without the chokes we'd have problems.

How could you have crosstalk when the DCSRC is only being used to generate a watchdog signal?

I've been using a DCSRC to generate the watchdog signal on a unpowered siding where locos are parked for a few years now with no problems. Siding is wired thru a toggle switch that connects it to the mainline. DCSRC is wired to siding in passive mode. Throw toggle to power siding on, watchdog signal is generated, start loco and run out onto main.

Talking about the DCSRC...didn't I read somewhere that it will be updated to run any loco regardless of address? 

Casey Jones2 posted:

How could you have crosstalk when the DCSRC is only being used to generate a watchdog signal?

Casey, you need to go back and read the original post.  I'm using a TIU channel to provide the watchdog and the DCS signal in the yard.  Barry brought up the DCSRC later in the discussion.  If you connect two DCS channels together, you will have problems.

Casey Jones2 posted:
Talking about the DCSRC...didn't I read somewhere that it will be updated to run any loco regardless of address? 

Are you sure you're not thinking of the feature on new PS/3 engines that allows you to set them to factory defaults using the DCSRC?  I've heard nothing about making the DCSRC universal, and I seriously doubt that will happen.

gunrunnerjohn posted:

...We have a rotary switch to select one of "n" tracks to power at a time

Is it a break-before-make?  I'm still fixated on eliminating the need to first go to the home/off position whenever changing active track!

As a general question to anyone who uses rotary switches to distribute track power to 1-of-many (roundhouse, yards, etc.) under what circumstances would you want a make-before-break switch...thereby powering up (albeit momentarily) two tracks at the same time?

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