Remote commander as DCS Watchdog Generator

I have done exactly what your describing.  Connect the DCSRC to your track passively.  When you toggle power on to the siding track you will generate the watchdog. Keep in mind this is only needed when grabbing power from a mainline already powered up with a TIU channel.   Why not just use a separate TIU channel for your programming track?  If having an isolated programming track is your goal I think utilizing a separate TIU channel would work better.  

(1) is power brought to the DCSRC or is it just powered by the batteries (I would guess this a passive mode if true?)

It is powered passively just by being connected to the track. When track power is toggle-switched on, the DCSRC powers up and generates a watchdog signal.

(2) what causes the DCSRC to generate the watchdog signal?   Will it do that in response to seeing the track power on its outputs that is switched on from the TIU?

It generates the watchdog signal every time it initially receives power (from the track), as if its was a TIU channel.

(3) can it remain active the entire time the siding is active, or does it need to be turned off after performing its function?

It just stays on whenever the track has power, and turns off when track power is turned off.

(4) when connected in parallel with the TIU, will the watchdog signal be broadcast over the entire layout?  If so, is that OK?

Yes, it will and that's fine. Nothing bad will happen. In fact, you could then run trains using Bothe the DCSRC handheld remote at the same time as running other trains with the DCS Remote.

Did you stumble across this thread?

Proposed Solution to DCS Watchdog in Yard Tracks (DCS-RC WD Gerber Files Added to First Post)

This was a little project to allow the DCS-RC to continually output a WD signal for yard tracks.

And the above little addon works really well I might add. Instead of the WD signal only firing once, it repeats about every second. So any PS2/3 engine parked on any yard siding will see it when the track is powered, and will come up dark and silent, instead of in conventional. 👍

Rod

I saved one of these boards for my yards.   I have a couple of the DCS-RC boxes squirreled away.

How can I get this watchdog signal generator for my sidings ?

Clem

Clem, the thread I referenced has all the design files to order the PCB from OSHPark and the parts list of cheap parts.  Since it's all thru-hole stuff, it's easy to assemble, and then you too will have a perpetual watchdog.

I just checked, and I have one of the kits I was offering remaining, send me an email and I can fix you up.  It contains all the parts needed to upgrade one DCS-RC box.

Thank you John

Clem

Thanks for the responses ...

Given the suggestions for the modifications to the DCS-RC ... should I assume that the WD signal’s duration is often too short for the locomotives to pick it up?   Is that why there is a desire (need?) to repeat it?

I have never had a problem with an engine missing the TIU's WD signal at system start up so I don't think the length of time is a factor. As for the actual length of time the TIU's WD signal lasts, others here could explain this better than I can, that is, if you are interested. 

The repeating WD signal is so you can power up a siding/spur/yard track etc. at anytime and the parked engine(s) will get a WD signal and do what they are supposed to. Otherwise the WD signal is sent only once when the TIU is powered up. Powering a siding connected to an already powered track won't give you a WD signal. 

I also have one of the devices for the DCS-RC that GRJ and Stan were kind enough to develop and they work great to eliminate this problem. This a a really cool device!

I'm considering another run of them.  If I do more, I'll change and add a pot so that there is no resistor selection to calibrate them.  I'll also add an LED so you can see the timing as you adjust it.  Stay tuned...

I think I better upgrade, I really like adjustment dials and flashing LEDs. 

Four would be a good quantity to have on hand too, so that's what I will order when ready. 

Something like this, same size as the previous board, just with the LED and pot.  If there's room above it, the LED could be on the top so you can see it easier while you tune, but it would be visible even below.

Stan had suggested these mods, so with the renewed interest, I'll see if I can build one and make sure everything works.

Looks great and I hope the prototype is a success! I agree the LED would be fine below, but wasn't there something about the case or something that was really close? I can dig mine out tomorrow if you want and try to get some measurements if need be. Right now, I forget what the DCS-RC thing looked like on the inside?

Would this be a stand alone item, or would I need the DCS-Commander as well?

The board is an add-on to a stock DCS Remote Commander receiver. It is placed inside the receiver.

To refresh everyone's memory, this is the original board installed, this one is the same size. 

For the new version the pot faces out between the silver crystal can and the larger IC on the left.  If there's room on top, you could just mount the LED on the circuit side facing up, but I'm sure it'll be quite visible facing down as well if there isn't room.

Thanks for the pics GRJ, I should have known you would have already thought of all that (and your memory is a lot better than mine)! 

I "believe" there's probably room for the LED on top, but I put it with the rest of the components.  Since this is a thru-hole design, putting it on the top is very simple, just put it there!

JK PHOTO, I too would like to do this watch dog signal generator project for all my toggled sidings. For now though, so that my engines remain dark and silent when power is toggled to a siding, I do these steps:

1. Lock the engine in conventional neutral (this is a good practice anyway if you never run in conventional cause it prevents run-away's).

2. Turn off the smoke and sound with the switches or pots on the engine.

3. When finished running the engine and parking it in the siding, shut off the lights before shutting it down.

Now the next time you go to run the engine and toggle the siding, it will be dark and silent without having to see a watch dog signal. And if you accidentally toggle twice, the engine won't take off at full speed. Next find the engine in your remote and start it up, then turn on the lights, just like a real engineer would do.

Pro's and Con's:

Pro. This one is personal. I've become annoyed over the years with that same "steam generator turbine whine" sound, on every MTH steamer when they start up. This "watch dog signal work around" eliminates that sound because it was already performed when the track power was applied and no volume to broadcast it.

Con. If you do want to hear the start-up sounds (especially if your like me and love the diesel start-up sounds) you have to remember to hit the shut-down button first, then the start-up button, if you want to hear those sounds.

This has been working for me until I get around to doing this project.  

Guys, I am just wondering what the addon LED does; I missed that part.

John if you want to part with one of the DCSRC's you have on hand I would sure take one? I could use another for my other yard, and I have a spare signal generator board left over from the first ones I ordered from you.

Rod

The add-on LED allows you to see when it's resetting so you can "tune" it to the 1 second beat.

OK thanks John, makes sense to me.  And the pot is to enable the tuning?

Rod

The green LED on the DCSRC itself blinks each time it resets with the add-on board.  Isn't that sufficient for "tuning"?

The trimpot is a nice and useful enhancement.

Probably is Stan, I didn't have one in front of me, and I wasn't sure what the indications were.  You can leave the LED and resistor off, so that's not really a problem.  The pot was really the thing that I wanted to do as swapping the resistors was a pain.

The new schematic...

So if the basic addon reset board causes the DCSRC to reset about every second or so, why is "tuning" needed? What did I miss?

Rod

The variability of the cap value and the IC trigger point makes the spread too wide to simply pick a set of components.  We had to calibrate them with a resistor selection, the pot just eliminates the need to test resistors before soldering them in.

Obviously, it could have been done with a 555, but as Stan pointed out, that would have run the current consumption up quite a bit.  Although there are doubtless tons of other ways to do this, this is the way we have.

Peeling the layer of the onion a bit.  There is actually a relatively small timing window around 1 sec or so where this scheme works. 

On the short end, you can't reset too quickly because measurements showed the DCSRC itself takes about 3/4 sec before it generates its watchdog.  Hence if the reset it faster than every 3/4 sec, you'd never get a watchdog at all!

On the long end, you can't reset too slowly because a DCS engine will decide to startup in conventional if it does not see that watchdog in a timely manner.  I can't recall the number but if you turn on a DCS engine in conventional, that decision window is pretty short.  In other words you hear the engine sounds start up in a couple seconds at most if there's no DCS.

So in such an environment where there are no MTH-provided specifications, a self-imposed timing requirement was determined.  This also eliminates any unit-to-unit variability as a suspect when troubleshooting on OGR.

That window is pretty tight.  In a sample of one, it was 1.4 seconds from applying power to a PS/2 3V model to conventional startup.  So, about 1 second is probably just allowing enough margin to prevent the startup while still allowing the DCS-RC to be able to spit out the WD signal.

OK understood. The first one I installed must have been a lucky shot as it seems to fire just about right on every second or so, and works exactly as intended in my TT yard. Hopefully the next one will work similarly. One other thing, can you retrofit the pot and LED to an original release PCB, or the PCB's different?

Rod

Rod Stewart posted:

...One other thing, can you retrofit the pot and LED to an original release PCB, or the PCB's different?

As I understand it, GRJ is designing a different PCB.  The new PCB adds space for a pot to adjust the "timing" rather that iteratively inserting different fixed-value resistor to "tune" the timing.  If you have an original PCB, I suppose you could mount the pot somewhere on the board and tack-in some short wires to add adjustment capability.

But if you have a working unit right now that blinks in the specified window, you should never need to re-tune it.

Yep, it's a new PCB.  I ordered some of them, and I'll post the design files and BOM here for anyone to order as they see fit.  Pretty hard to see how it could fail, I just replaced the 1M (nominal) resistor with a 750k and a 1M pot.  My experience was that I needed more than 1M, usually about 1.2m-1.3M, so I slanted the values that way.  The LED was just a frill that used one of the extra buffer sections, a resistor, and the LED.  I posted the new schematic a couple posts ago.

Thanks, GRJ! I will be looking forward to ordering some PCBs. And, Thanks again to you and Stan for another fine project. 

Hello GRJ .... please put me down for two of the kits to modify my DCS-RCs ... Thanks!  Joe

JK Photo posted:

 I am building a new layout utilizing a TIU and would like to dedicate a siding as a programming track, so that adding an engine will not interfere  

I setup this with a Z1000 powering a section of track and the DCSRC powered in passive mode. Initially I inferred that this setup would be sufficient for configuring a dedicated programming track. Is it correct that in addition to the DCSRC setup as passive, you must also connect to a TIU channel for this to work?

Tom,

Is it correct that in addition to the DCSRC setup as passive, you must also connect to a TIU channel for this to work?

The DCSRC can only operate DCS engines that are factory-new or reset to Factory Settings. If you want to simultaneously operate multiple DCS engines independently of each other, you need to have a TIU channel connected to the track.

Everything that you need to know about DCS is all in MTH’s “The DCS Companion 3rd Edition!" This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!

The DCS-RC is good to keep them dark and silent.