Watchdog signal

From memory, the "Watchdog Timer" signal only comes on when the TIU is first powered up. Thus, if toggle switches are used to turn-off/turn-on track power to yard tracks, sidings, etc., there will be NO "Watchdog" signal transmitted if the TIU is already powered up. 

HW is correct, when the TIU channel first receives power, the WD is transmitted for a few seconds.  If you later power a siding on, but not the TIU channel, there will be no watchdog.  There are many work-arounds for sidings, we've talked about them many times here.

I've used a simple light switch and it works. So I bet there's something else going on such as too much amp draw per size of wire? too small (amp) a switch? or similar issue.

When the switch is on ask him to check the track signal strength of that siding.

Engineer-Joe posted:

I've used a simple light switch and it works. So I bet there's something else going on such as too much amp draw per size of wire? too small (amp) a switch? or similar issue.

None of the above! Remember that the "Watchdog" signal is ONLY activated when the TIU is initially powered up. Thus, whenever the power is turned back on to ANY track, no matter WHAT sort of switch is used, there will be no "Watchdog" signal generated it the TIU is already on.

When the switch is on ask him to check the track signal strength of that siding.

The DCS signal strength has NOTHING to do with the initial "Watchdog" turn-on.

Yes Sir, you are right if the switch goes straight to the track. I have my switch cut in between the inputs of the TIU channels. So when I throw the switch, I get the watchdog signal.

The watchdog signal gets sent whenever any TIU channel goes above zero? volts. So when it gets input power from a switch, it sends the watchdog.

 Also, if you have too many engines parked on a siding at power up for example, some of those engines won't get the watchdog signal!

Describe fast enough? How is it wired?

A buddy of mine  is having the problem of the dcs signal not getting thru a toggle switch fast enough to a passing siding to keep from starting up in conventional.

I'd have to say there's a different problem brewing if it's the speed of electricity through a toggle switch!   My guess is he's switching the siding power and NOT the TIU channel power.

Yes, I bet you're right. He's not faster than the speed of light???? 

Maybe he's going for the switch with the layout running. He should be turning the siding on if wired after the TIU, and then applying power.

Joe, this is typical of a 3rd hand account of a problem, the only way to really know what is actually being done is get it from the horse's mouth.

Let us talk directly to the friend!

Bingo!

gunrunnerjohn posted:

HW is correct, when the TIU channel first receives power, the WD is transmitted for a few seconds.  If you later power a siding on, but not the TIU channel, there will be no watchdog.  There are many work-arounds for sidings, we've talked about them many times here.

Out of curiosity.  Have you run across the idea of momentarily interrupting the INPUT to a TIU channel whenever a new siding is toggled-on?   What I don't know is if the TIU can "deal" with this momentary (I'm thinking, say, 1 second) interruption and if this interruption is enough to force the channel to issue a watchdog.  This would be an alternative to the DCS Remote Commander methods.  I'm imagining you'd want the TIU powered by the AUX PWR input which presumably keeps the TIU microprocessor running to remember what's going on in the event the power is interrupted to the FIXED-1 channel.

It's presently half-baked but I'm imagining a cheap $3 eBay timer-relay module that is triggered when any one of many toggle switches goes from OFF to ON.  

Never really considered it Stan, but it might work.  It would clearly stop things on the channel, I'm not sure how desirable that would be.  Not the way I'd want to do it, so someone else will have to research that idea.

Engineer-Joe posted:

Let us talk directly to the friend!

He does not have a computer or tablet so it hard for him to respond. He could use his phone but it being so small it is hard to type. This is why I'm trying help from a distance. 

Give him some ideas on how to improve the dcs signal at start up! This is his basic issue.

I never had an issue like this on my former 25x14 dcs layout and I used many toggles in my yards. Has MTH Changed some anything that I do not  know about? There must be something causing this on so many layouts.

Every layout is different! That is not a answer. Why can't MTH make this easier, if it is a known problem, fix it. 

Dave

Depending on the engine and if PS2 or PS3, I have three different issues when I flip a toggle switch AFTER power has already been applied to the TIU.

1) An engine will just sit there silently waiting.

2) An engine will start in conventional and just sit there waiting for a conventional instruction or to be started up in DCS.

3) An engine will start and immediately take off at rocket speed. 

I can live with 1 and 2.  I hate number 3.  It only does it to 1 engine and it's not consistent.

Ron

#1 any certain PS3 engine of a manufacturing period had the wires routed touching or next to the Torrid coil on the board. This causes issues with lower signal and missing the watchdog.

#2 too many engines and or lighted cars on a TIU channel drawing down the power also draws down the signal. This also affects the watchdog strength in my experience. If the number can't be reduced than maybe passive wiring with a choke might work better?

In this same instance, too small a gauge wire or any power choke point like track connections or joints can cause this issue.

#3 TMCC/Legacy equipment or anything with caps can affect the watchdog and signal strength.

#4 PS2 engines with batteries that are weak or failing can cause all types of operational issues.

#5 is part of the others but.... too much track on a single TIU channel.

#6 poor power supply (to the track). One that is choppy or pulsing for example. I find this issue might be the reason Ray Manley suggest using the Bridgewerks power supplies for G scale. I should let him tell us here though. A lot of users on this forum, use larger AC packs like a MTH Z4000 or similar Lionel. So this doesn't apply for them.

 I run MTH equipment almost exclusively, yet I like to use the Lionel PH180 bricks for many reasons. I have 4 in use right now. If I stayed with AC on my G scale I would have at least 12 in use right now.

Stan, any channel of the TIU sends out the watchdog when power is applied to my knowledge. That's even when the aux in power is used.

Joe, my question is how brief of a power interruption will trigger a TIU channel to issue the power-on watchdog.  For example if you pull INPUT power to a TIU channel for 1 minute and then restore power clearly a watchdog will go out on that channel.  But how about if you remove INPUT power for only 5 seconds?  Or only 1 second?  Or 1/10th of a second?  In other words what is the shortest interruption that will "trick" the TIU into generating the power-on watchdog?

Again, the idea is to briefly interrupt the power to the INPUT of a TIU channel whenever a toggle switch is thrown that will apply the OUTPUT of a TIU channel to a siding, spur, or whatever.  This interruption would be performed automatically by electronics adding, say, $2-3 per toggle switch. 

The interruption must be as brief as possible so that any DCS engines that are active on the OUTPUT will not hiccup in any objectionable manner.  If the method pans out I can imagine it being best-practice to halt any active DCS engines that share the TIU channel to be toggled ON to the siding.  As to whether this is a burden is a to-each-his-own.

Why couldn't the watchdog code be written into the engine SW?  Let the engine decide what it wants to do with the new found power.

I got it now Stan. So I could guess that the TIU channel has to see zero volts than some higher value. Then it would issue the watchdog.

I will go test and see what really happens to the best of my capability here. I can't say it will be perfect.

Not to hi-jack this thread, but Joe, could you show how you have your light switch wired?

Stan, I should have connected my signal strength box to the TIU to verify the watchdog. It's out back in my shed and my girl is asleep. So I just did a quick test to post something here.

 If I take my light switch and flip it off and right back on, the engine on the rails starts right up. If I throw the switch off and pause, it doesn't. I didn't have the means to time the pause. I would just state that I only did it once, and the pause was for a second or two at least.

 It wasn't much of a clinical trial. It was just to show that a very brief interruption of power doesn't trip the watchdog.

Mike G, I could try and draw something or even show a pic. All I did was send the hot wire thru a regular wall light switch. So a jumper wire comes from a powered channel's red input going to the switch. The output of the switch goes to the next channel's red input.

It's so simple that I don't think a picture is better? Words may seem worse than a picture here though. So I will get a pic.

this older picture doesn't help you I'm afraid? I have changed out the wiring *. I think a drawing might be better for you? If I took another picture, it wouldn't show you what's actually wired.

I don't have any way of doing a drawing. I'd appreciate any help here.

Fixed #2 input comes from the handle of a MTH Z4000. There's another jumper wire that takes that same red wire to a terminal (screw) on a light switch. From the other terminal of that light switch, a wire goes to the top variable channel red input. The black jumper wire just goes Straight thru from fixed 2 in. Most TIU's do that internally anyways.

* I had to change some wiring because of the internal jumping of the black wire inside the TIU. It carried the TMCC signal to stuff that caused issues. I can't have that signal on my 2 rail loops. So this TIU is now strictly for the 3 rail upper loop. The wires have been enlarged as they now carry more track and amps. Originally it was some old spare lighting wire just for a test siding. Now it's a passing siding so it's 14 gauge.

david1 posted:

He does not have a computer or tablet so it hard for him to respond. He could use his phone but it being so small it is hard to type. This is why I'm trying help from a distance.

 FWIW, I have already helped your unnamed friend solve his yard WD issue.  And, for your information, he somehow is reading the forum and saw you posting about his problem.  So maybe he's not quite as helpless as you would like to believe.

david1 posted:

Give him some ideas on how to improve the dcs signal at start up! This is his basic issue.

Dave, that is NOT his issue!  His issue is how and when the TIU sends the WD signal.  I think it's time for you to invest in Barry's book and read how and when the WD is generated.

david1 posted:

I never had an issue like this on my former 25x14 dcs layout and I used many toggles in my yards. Has MTH Changed some anything that I do not  know about? There must be something causing this on so many layouts.

You must be a magician!  There's no way that just turning on a siding that is powered from an already powered TIU channel generates a WD signal.  If you managed to make that happen, you're the only one on the planet that has that kind of magical powers!  Or, perhaps, your layout was haunted and there was a ghost that was operating the TIU channel power? The rest of us all have to design layout solutions to solve the problem, since clearly we don't have such abilities.

The only time when the WD is generated from a TIU channel has not changed over the years.  It's very simple.  When a TIU channel sees power coming on from an off state, it generates a WD signal for a set period of time.  That time has varied from version to version, but it still only happens at power-on of a channel.

david1 posted:

Every layout is different! That is not a answer. Why can't MTH make this easier, if it is a known problem, fix it.

It's the way that the TIU has managed the WD from the earliest TIU version to the present day.  Every layout is different, it just so happens that this behavior is a constant.

As to why MTH doesn't solve it, you'll have to ask them.  I've often wondered why the TIU doesn't always generate a WD signal, but I suspect it's due to the possibility of collisions with the data coming back from the locomotives.  However, the odd thing is, using the perpetual watchdog timer board in a DCS Remote Commander and connecting it to yard feeds somehow works fine, so the presence of those signals apparently doesn't totally screw things up.  To refresh everyone's memory, the discussion below started out a few years ago when I was trying to figure out how to do the same thing for a bunch of yard tracks.  Stan came up with the idea of using the DCS-RC to generate the perpetual WD, and I designed a PCB to capture that idea.  See the thread here:

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

A bunch of people have used these boards with the DCS-RC package to generate yard WD signals.  AFAIK, this is still one of the better ways to address this issue, at least until some future version of the TIU generates a WD continuously.

Ron045 posted:

Why couldn't the watchdog code be written into the engine SW?  Let the engine decide what it wants to do with the new found power.

How would it know if it were in conventional or command mode?  The WD is what switches a DCS locomotive into command mode.  In the absence of the WD, after a delay, it comes up in conventional mode.  Given that operation, I don't see how the engine can decide that on it's own.

I am interested to hear more about this engine. The first thing I think of is an engine locked in forward direction! Why it only does this sometimes? How's the battery? I'm wondering if there's a power fluctuation and the battery is weak, the engine gets the go command?

I had a PS3 engine do the same. A conventional reset would help for a while, but very difficult to get because it wasn't in neutral. Have you bent the capacitors down and rerouted wires? None of my PS2 engines ever miss the WD, but the PS3s miss it quite often, especially in an MU.

When a PS2 or PS3 locomotive comes up in conventional mode it is in neutral.  However, a brief power interrupt switches it to forward and with full track voltage, the effect is immediate, it takes off!

FWIW, I notice that my PS/3 engines are more sensitive to track signal and sometimes miss the WD as well.  Rarely does any of the PS/2 engines miss it.

OTOH, I find that with a sub-standard track signal, I have a harder time adding a PS/2 engine than a PS/3 engine, so figure that one out!

I thought I'd throw my quarter in the pot here. I have two PS3 engines that sometimes miss the "DOG". As GRJ mentions above some PS3 engines seem to be more sensitive to the signal, weather it be poor generation from the source (TIU), dirty track or just those spots on the layout that don't seem to transmit the signal that well.

John also mentions the thread about a solution for signal generation in yards/sidings after the TIU has already been powered up. In another thread (relays for track power using AIU) Stan comes up with the idea of using an additional timer relay to trigger John's DOG module for this purpose. I'm using John's module along with a 555 timer relay for my roundhouse and turntable whiskers. This timer is adjustable from 1 to 10 seconds. I let the timer run for 10 seconds and up to this point have not had any problems with these two engines missing the signal.

Thank you John and Stan for all your contributions to this forum.

Ron045 posted:

1) An engine will just sit there silently waiting.

2) An engine will start in conventional and just sit there waiting for a conventional instruction or to be started up in DCS.

3) An engine will start and immediately take off at rocket speed. 

I have to recant my statement on #1.  It you wait long enough the engine will start conventional.  About 20 seconds.

The second video is my problem child.  It takes off in reverse with no user input.

MTH 20-20271-1 PS-3.

By the way... I had two engines running on the tracks during this test.  The Gp30 with the delay was on track powered by the right handle.  The SD70 was on track powered by the left handle.

John H posted:

I had a PS3 engine do the same. A conventional reset would help for a while, but very difficult to get because it wasn't in neutral. Have you bent the capacitors down and rerouted wires? None of my PS2 engines ever miss the WD, but the PS3s miss it quite often, especially in an MU.

Ron045 posted:

...

The second video is my problem child.  It takes off in reverse with no user input.

MTH 20-20271-1 PS-3.

John, when you say "would help for a while" does this mean it would again become locked-in-forward or locked-in-reverse after some number of operating sessions?  I'm sure it varied but can you ballpark how far apart, or how often, or whatever?  

Ron045, I think your engine is locked-in-reverse for conventional operation.  You can see the headlight coming on immediately...but nothing else.  Someone correct me but I believe this is a definitive indicator that a PS3 engine has missed the watchdog, has decided to startup in conventional (not DCS command), and is now charging its internal supercap.  Then, after 10+ seconds the supercap charge reaches some level that MTH has deemed enough to start operating, the engine sees that it is locked-in-reverse and takes off.  Note that when it hits the dead-track in your video it does not sound like a complete shutdown sound.  My interpretation is the supercap was still charging and did not reach a full charge; this is important because you'll need a fully charged supercap to remove the locked-in-reverse condition.

As John H says, removing the locked-in-reverse condition can be a nuisance.  You'll need to put the engine on a longer piece of track than it's on right now.  Power it with the Z-4000 directly so it powers up in conventional.  When it does take off in reverse after 10+ seconds, lower the Z-4000 voltage until the engine just stops.  This will be around 7V or 8V as displayed on the Z-4000.  Now perform the W-B-B-B-B-B conventional reset.  Hear the double-honk acknowledgement from the engine.  If you are not familiar with this conventional reset function, I made this video a while back.  You absolutely must hear the double-honk...keep trying until you do!  As John H says, it can be difficult to perform this reset if the engine is moving so that's why you slow or stop the engine by adjusting the voltage.

Then, remove power from the track.  You must hear a complete shutdown sound from the engine; again, it was hard to hear but the shutdown sound in your 2nd video seemed like it terminated early(?).

Then, power up again and see if the engine takes off in reverse after the startup supercap charging delay.

Engineer-Joe posted:

...

 If I take my light switch and flip it off and right back on, the engine on the rails starts right up. If I throw the switch off and pause, it doesn't. I didn't have the means to time the pause. I would just state that I only did it once, and the pause was for a second or two at least..

...

Thanks for the experiment.  Since the engine did NOT start right up after a 1-2 second power interruption at the TIU INPUT, this suggests the TIU indeed decided to send out the watchdog. It sounds like there is some hope for this approach. 

Again, this is just another thinking-out-loud while sheltering-in-place hare-brained scheme.  I think most guys have settled on one of the methods referred to in earlier posts.  I'll leave it as that unless anyone actually wants to discuss it further. 

I agree with Stan that the engine is probably locked in conventional reverse. I had a brand new CR SD80MAC do that after getting scrambled in a consist. I had to reset it. There were 2 PS2 engines in the consist that ended up having failing batteries. I think that drove the software nuts?

I had another engine do that right out of the box.

For some reason in this scrambled state, they miss the watchdog. After resets, they have performed flawlessly ever since.

I think there was a certain release of engines (2 years ago?) that all the sound sets needed a conventional reset. At least the ones I got, and the ones I read about on this forum, that were giving issues.

Again a channel that's overtaxed, doesn't keep all engines quiet. My engine yard worked with around 5 engines in it on a single TIU channel. I can fit up to 18 engines. As soon as I parked around 11 there, all heck started breaking loose. 

Whatever the reasons, when it's a PS3 engine, I'd check the wire routing first. Blackened paint on the truck's wire connector screws second.

Stan2004.  That worked.  No more taking off.  

Thanks. Ron

https://ogrforum.com/...ps3-stuck-in-reverse