Thanks! I have abandoned trying to use the relay board that I had previously bought and purchased the 4 relay board that you recommended. The screw connectors are a bit easier to deal with. Also bought the "wall-wart" to power it. Im still feeling my way around the electronics.
I am still trying to understand why the AIU cannot handle this directly without adding another relay board.
The reason is that track power may involve substantial amperage if there is a track short, exceeding the capacity of the AIU relays. It is cheaper to replace an external relay with burned contact points than an internal AIU relay. Shorts in accessory and switch circuits are rare. Unfortunately, not so with track circuits. Even without a short, track currents up to 10 amps are not unusual, which if I recall correctly, is double the rated capacity of the AIU relays.
Ok, that makes sense. I am surprised that MTH hasn’t marketed a solution to this issue.
Too easily obtained from Chinese sources, and uncompetitively cheaper.
Do be aware that if you have many AIU accessory relays activated at the same time, you may need a larger power supply feeding the AUX port in the controlling TIU. I beleve 2.5 amps is the latest recommendation in case you have this situation. (5 AIUs per TIU, time 10 relays per AIU, equals 50 relays).
George Mason posted:Ok, that makes sense. I am surprised that MTH hasn’t marketed a solution to this issue.
I'm speculating, but I'd think their logic might be that whatever protection you have in place for your transformer (fuse, breaker, whatever) would interrupt the short before it does damage to the relay.
As discussed earlier in the thread, some reasons you might want to use an AIU in conjunction with an external relay:
1) Larger current in the external relay. As RJR notes the internal AIU relay is 5 Amps and the recommended current is even less.
2) Ability to use much thinner control wiring from AIU to distant relays. This can drastically reduce wiring bulk and cost.
3) If using DCS, there is anecdotal evidence that simpler is better with respect to wiring "geometry". If you run the "hot" power from block-AIU-block the DCS signal is also running over that extended distance. If the external relay is close to the block, the DCS signal travels over a much shorter distance.
4) The internal SPDT (single-pole, double-throw) relay may not be the right contact arrangement. For example, the Tortoise switch machine uses a DPDT (double-pole, double-throw) relay in some wiring configurations. And MTH has published how to drive such an external relay from the AIU. I realize this has nothing to do with a block power application.
5) Separate from the contact arrangement, the external relay module can provide additional functionality. For example, for a couple of bucks there are relay modules that have timing capability. So the external relay can be limited to turn on for no more than 5 seconds (or whatever). This can be handy if the ACC(essory) port is controlling an uncoupling electromagnet which might burn up if power is applied for too long.
6) Finally, an out-of-leftfield idea is the AIU relay can "press" the button(s) of a remote control wireless fob that then controls a distant relay. I just recently posted this on the O gauge archive here.
Ok, that makes sense. I am surprised that MTH hasn’t marketed a solution to this issue.
You may call this an “issue”, however, It’s not actually a problem. The AIU is designed and intended to operate switch tracks and accessories, not engines.
Ok! I now have the parts that I need. It appears that I can isolate a siding by removing the jumper on the Fastrack switch extension. On the relay board, do I connect the wire from the AIU to the IN1 to 4 connections? And the hot wire to the COM1 to 4 connections at the relays? What does NC1 and NO represent? I'm assuming that NO1 is the output to the center rail of the track.
I know that these are rather basic questions, but I don't want to screw up the electronics. Speaking of which, I have a circuit breaker between the TIU and the tracks. Any other protection that I should add?
Thanks!
Hopefully above diagram will clarify matters. Diagram should be click-able to get better resolution. I show only 3 of the 4 channels used to show you can choose to use any or all 4 channels. The "hot" or center-rail power (thick wire) connections are on the right or relay side of the module. The NO (Normally Open) screw-terminal gets connected to the COM (Common) terminal for a particular relay channel when the TIU ACC port triggers the relay. This particular relay module is nice in that an LED indicator turns on when the TIU ACC port is triggering the channel; you'll also hear the AIU internal relay "click" along with the relay module's relay.
As for circuit protection, what you're doing here does not in itself increase/decrease the need and/or effectiveness of what you already have. In
Wow! That’s great! I’ll let you know how it goes! I’m just working with a temporary layout to get familiar with what’s required to use the electronics.
Thank you!
Instead of running the DC+ from the wall wart to the AIU, I Used the “U” terminal on my Lionel ZW. The hot, from the ZW goes to the output side of the relay board. With NO1 going to the center rail, I have no power on the siding. If I switch the NO1 wire to the NC1 post, I have power to it. When I select off, it still has power. Also, the relay LED does not light.
I know that I have something wired incorrectly. I just don’t know what.
help!
Stan knows his business and you should not vary from his diagram. I won't even read past your first sentence. When you introduce the transformer terminals to what he labels DC input from wall wart, you are now applying AC and the system won't work. AC should only be applied on the relay contacts side, as he has shown
Sorry, I didn’t imply that Stan doesn’t know his business. Rather, I was displaying my ignorance of electronics. If I offended anyone, it wasn’t intentional.
I changed the wiring, and it’s working perfectly!
Thank you!
Don't sweat it. No one was offended. Glad this helped. Everyone's knowledge of any subject began at 0.
RJR posted:Don't sweat it. No one was offended. Glad this helped. Everyone's knowledge of any subject began at 0.
One last thing. Should all of my track lines be powered through the relays as well? I am getting some DCS issues when starting an engine from the siding. It’s as though the signal from the AIU is not transmitting onto the siding.
George Mason posted:One last thing. Should all of my track lines be powered through the relays as well? I am getting some DCS issues when starting an engine from the siding. It’s as though the signal from the AIU is not transmitting onto the siding.
What exactly are you seeing?
When you initially apply track power to a DCS engine, the engine must see DCS activity within a few seconds for it to stay silent/shut-down in command-mode. Otherwise it reverts to conventional-mode and starts up with sounds and lights. Is that what you're seeing?
Yes, that’s it. I just finished connecting the mainline to a second relay on the board and that seems to correct the problem.
I’m still seeing the engines starting up when power is applied to the tracks. I’m able to shut them down and restart them using the remote. But, if I don’t get to them soon enough, they start running in conventional mode.
How do I ensure that the dcs signal gets there before the engines decide to power up?
George Mason posted:I’m still seeing the engines starting up when power is applied to the tracks. I’m able to shut them down and restart them using the remote. But, if I don’t get to them soon enough,they start running in conventional mode.
How do I ensure that the dcs signal gets there before the engines decide to power up?
When you saying "start running in conventional" do you mean they actually take off (moving)? If that is the case, then the engines are locked in conventional Fwd or Rev which can be reset. But if the engines just start up in conventional Neutral with sounds and lights, then I'd ask how truly important it is that the engine come up silent. That is, if you have a lighted passenger cars on the siding, those lights will turn on too (not that they would be off otherwise!). One thing guys do is turn down the mechanical volume control knob so that if the engine indeed starts up in conventional, it will at least be silent so just the lights turn on which may not be as "offensive."
But lets say if you absolutely positively need/want the engine to power up silently in DCS command mode. And it's inconvenient or impractical to navigate the DCS remote from the AIU Accessory menu (that turns ON the siding power) back to another menu which issues a DCS command. Note the command does not even have to be to the specific engine address on the siding. Any DCS command (even to a different engine) sent out on the track will silence the engine on the siding if done so within a timely manner.
Here are two options; I'm sure there are more that one of the DCS gurus might offer.
1. Depending on how many sidings you are controlling, you can re-configure/re-wire so that when you power-up the siding with the external relay, you simultaneously power-up a TIU channel. When a TIU channel initially turns on, it sends out a benign DCS command (aka "watchdog") that a DCS engine will recognize as DCS activity and hence remain silent and shutdown in command-mode. The reality is this can be impractical in a layout with many sidings or, say, a turntable with multiple whiskers/stubs.
2. Attach a DCS Remote Commander to the siding.
You may have one lying around from an MTH Starter Set. A DCSRC has the useful feature of generating the "watchdog" when it initially receives track power. Obviously if you have one sitting in the closet this is a zero-cost solution. OTOH, if you have to buy one (maybe $25 or so?) it gets back to how much you really want/need the silent start up behavior.
Thanks for the info. The I have two track ovals and one siding. All are powered with an AIU that triggers a relay for each. The engines will occasionally turn on with no lights and I am unable to control them with the remote. Although, I can shut them down with the remote. And then restart them, after that they work normally. I would prefer that they not power up when the track is powered. Especially the siding.
George,
Although, I can shut them down with the remote. And then restart them, after that they work normally.
Skip the Shutdown and just use the Startup command.
It's not necessary to shut the engine down first to go from conventional; mode to DCS command mode.
Is there any way to prevent them from starting when I apply power to the track?
George,
Is there any way to prevent them from starting when I apply power to the track?
Missing the Watchdog Signal
If individual DCS engines miss seeing the watchdog signal, they can be either brought directly into DCS active mode by pressing the Start Up key or put into DCS stealth mode by pressing the Shut Down key. However, this is not the same for lashups.
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.
 | This and a whole lot more 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! |
Stan came up with a cool little board for the DCSRC to solve the issue of yard tracks and watchdog signals, I added a bit of value by turning it into a little PCB that made it easy to fabricate. It's all described in this thread, you have to read down a couple of pages before you get to the actual project. The board is simply added to the DCSRC to provide continuous watchdog signals.
Thanks John! I guess I should start accumulating these for later when I start building a permanent layout!
The DCSRCs are selling for $40 and up on eBay. I suppose that I could power all of the sidings by going from the AIU to a relay and then to a DCSRC to power all of the sidings?
gunrunnerjohn posted:Stan came up with a cool little board for the DCSRC to solve the issue of yard tracks and watchdog signals, I added a bit of value by turning it into a little PCB that made it easy to fabricate. It's all described in this thread, you have to read down a couple of pages before you get to the actual project. The board is simply added to the DCSRC to provide continuous watchdog signals.
Proposed Solution to DCS Watchdog in Yard Tracks
Are you selling these?
I sold them in kit form in the past. I still have a couple of blank boards, so if you wanted to build one, it's possible. The parts are all generic, and I may have some or most of them as well. Here's the BOM and a shot showing it mounted on the DCSRC.
John, how much do you want to fabricate one for me? You can email me at:
gemason@gmail.com
Thank you!
Hi John. I am interested also . Please e- mail me - katy409@yahoo.com. Thanks, Art
At this point, I don't really have time to be building these. I have posted the files to order the boards from OSH-Park, and like I said, I have a couple of left-over blanks.
How do you want for one of the blanks? I’m a user of electronics, not a builder, but I’m willing to give it a try.
Send me an email and I'll dig out the blanks and the components I still have for the build. I may have all you need, I didn't do an inventory when I looked in the box. I know I have the IC and several of the other parts.
Let me know if you don’t receive my email.
George Mason posted:The DCSRCs are selling for $40 and up on eBay...
Note that you only need the "receiver" of the DCSRC. You don't need the handheld remote in this specific application. If you bide your time on eBay or even on OGR Buy-Sell you ought to be able to get one for much less. For example, here's a receiver-only that went for <$20 all-in.
Patience!
George Mason posted:Thanks John! I guess I should start accumulating these for later when I start building a permanent layout!
So if I understand, wrt the AIU and relays, you are kind of in the experimentation phase getting your ducks in a row for the permanent layout? Do you know how many AIU-controlled sidings you plan to have? And are they grouped together like in a yard or a roundhouse turntable?
That is, if you can't get an assembled (and tested) DCSRC with the Perpetual Barking Watchdog modification, it can be a challenge if you're not comfortable soldering and managing somewhat tiny electronic components. To that end, depending on how complex your layout will be (number and placement of AIU-controlled sidings) I think I have another method that should not require any soldering. It still requires a DCSRC but not the modification; it would use low-cost ($2) eBay relay modules to momentarily attach a stock (unmodified) DCSRC to a siding when it is turned on.
If this is of interest I can write it up if for no other reason than it might further clarify what's going on with a DCS siding that is turned-on by a toggle-switch or AIU-controlled-relay after the TIU is already up and running.
My old age must affecting my thought process. At this point, I have two groups of sidings planned. I am already using relays between an AIU and the tracks. If I place a DCSRC between each relay and the track(s) they are controlling, then the engines should see the signal and remain “asleep”.
My only concern is once all is powered up and I reach for the TIU remote, will the signal from the TIU pass through the DCSRC to the engines and be recognized by them?
Definitely a simpler approach if it works. It seems to me that MTH left a few gaps in their DCS system/devices.
Thanks!
I think Stan is suggesting yet another relay that connects a DCSRC to the track when the track is powered up, not the one that is supplying power to the track. One thing that you have to be aware of is, powering multiple sidings up won't get you the WD signal for the ones that are powered up after the initial siding is powered up.
George Mason posted:... It seems to me that MTH left a few gaps in their DCS system/devices.
As Barry points out earlier, the AIU (Accessory Interface Unit) is meant to control turnouts/switches (via SW ports) and accessories (via the ACC ports) as opposed to engines. But to your point, I think it is a fair criticism/observation to ponder if the AIU could have been designed to better control power to engine sidings, roundhouse stubs, etc. For example, MTH could have included some setup mode for an ACC port where after you turn it on, it the TIU would automatically send out the magic "watchdog" DCS packet that would keep an engine silent and shutdown. For all I know this has previously been suggested and it's on some nice-to-have wish list along with dozens of others. Meanwhile, back at the ranch, we have to work with what we have. That is, the "manual" workaround is as described earlier to use the remote to press some sequence of buttons to send out DCS activity to inform the newly powered engine that it is in command-mode and hence remain in shutdown.
So back to the DCSRC workaround to automatically send out DCS activity when a siding it initially powered.
As I read your last post, there may be a misunderstanding. The benefit of the modified DCSRC is you only need 1 DCSRC for an entire yard of multiple sidings where power is controlled by AIU ACC ports (or manual toggle switches) . Yes; you could attach 1 DCSRC for each siding but that gets expensive rather quickly! So I just want to be absolutely clear that we're talking about a method to use one DCSRC to generate the magic DCS activity signal (aka watchdog) for a group of many sidings such as on a yard or roundhouse.
So if your proposed layout has 2 yards with, say, 5 sidings per yard, the idea is you would need only 2 (vs. 10) modified DCSRC receiver units. You still need 10 AIU ACC(essory) ports to individually control ON/OFF power to the 2 x 5 = 10 sidings.
Sounds like George really needs a couple of the A&T Perpetual Barking Watchdog boards to equip a couple of DCSRC units.
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