DCC 'slaving' A & B units

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DakotaLove39

Always Improvising
Hello folks.

I'll preface this by saying I'm pretty bad with decoder programming. I know how to do it, but I have difficulty figuring out what values should be programmed into what CV.

I have a pair of Walthers Proto-2000 E7's, both are now DCC equipped. Loco #20B has cab figures, and loco #18A does not. I cannot ever imagine a reason why #18A would ever be used by itself and I am wondering if I should, or can, just program #18A to the same address as the other (2018), and set the decoder's direction value so that both locos do the exact same thing at all times without needing to be consisted? They will be coupled back-to-back at all times when used together. I have already run these units in tandem on separate loops of track and I have determined that they are essentially factory speed-matched.

Should anyone see this post that also owns Walthers Proto-2000 E7's, I have a question about getting the Mars lights to work, also. I went with a simple Digitrax DH126, quick-plugged to the factory motor board. The Mars light is already wired, but I don't know which function it is wired to. The board does not provide this information.
IMG_20180903_225709782_LL.jpg
 
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tootnkumin

Well-Known Member
Staff member
There seems to be pretty much a standard for what might be called the "standard" lights. f0 for h/light, rear light, changed when selecting the direction, in the case of Mars, it can be either f5 or f6.. Number boards can be wired to either of those, or most commonly to f0 as well, coming on/off with the headlight. f7 is usually for dimming the h/light (Rule 17) Ditch lights also can be wired to f0 if you just want them on/off with the h/lights, or you would use both f5 & f6 (one function to each) in order to make them flash alternatively. It's a matter of deciding what you want to do which.

The PA with Tsunami I recently put LEDS in, I was able to wire the Mars light LED to f5 only, set it's CV to a value (forget which as writing) and have it produce an acceptable Mars effect. I have f6 controlling the the number boards on/off and f7, the dimming. You would have to check the CV and values that operate the various f functions for your Digitrax deccoder. The info should be available on their website.
 

tootnkumin

Well-Known Member
Staff member
As far as the programming the locos to the one long address, check them as to how they respond to throttle commands running together, but seperated by a couple of inches and adjust the power inputs to each to match them if necessary. Usually the same brands won't need that, but there could be differences in how they start together, small discrepancies won't matter. The only thing is, if you do so assign the addresses, they will always have to run together. If you want to run them seperately, then they will need individual addresses and be consisted when put together. You can still consist them tail to tail, it's just a matter of choosing the reverse direction for the back loco when setting up the consist. This will depend on your DCC system as to how this is done.
Just a thought on consisting using the same number for both. You may be able to set the rear, reversed loco to always run in the reverse direction i.e. in unison with the front one, with a CV setting, or otherwise reposition the wires to the motor, so that it always goes backwards when your controller selection says forwards.
 
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DakotaLove39

Always Improvising
As far as the programming the locos to the one long address, check them as to how they respond to throttle commands running together, but seperated by a couple of inches and adjust the power inputs to each to match them if necessary. Usually the same brands won't need that, but there could be differences in how they start together, small discrepancies won't matter.
Yes, I already addressed this. I have tested both locos on separate loops but working as a DCC consist, and they perform indentically.
The only thing is, if you do so assign the addresses, they will always have to run together. If you want to run them seperately, then they will need individual addresses and be consisted when put together. You can still consist them tail to tail, it's just a matter of choosing the reverse direction for the back loco when setting up the consist. This will depend on your DCC system as to how this is done.
I'd rather not ever have to bother creating a system consist for these two as it strikes me as being a giant pain in the butt at the club layout. If #19A is being used, it's because #20B can't do the job alone. #19A will never be used alone.
Just a thought on consisting using the same number for both. You may be able to set the rear, reversed loco to always run in the reverse direction i.e. in unison with the front one, with a CV setting
I.. already mentioned that.. yes.. Finding the CV is easy, I was just asking if permanent consisting in this manner is accepable or if it is prone to problems.
 

Iron Horseman

Well-Known Member
I cannot ever imagine a reason why #18A would ever be used by itself and I am wondering if I should, or can, just program #18A to the same address as the other (2018), and set the decoder's direction value so that both locos do the exact same thing at all times without needing to be consisted?
Absolutely, yes. It is bit 0 of CV29. However, depending on which DCC control unit you have, many of them have a programming option for "loco" direction where you can just choose forward or reverse.

I have a question about getting the Mars lights to work, also. I went with a simple Digitrax DH126, quick-plugged to the factory motor board. The Mars light is already wired, but I don't know which function it is wired to. The board does not provide this information.
First check that the headlight is 12V because that is what the output of the decoder is. I think the loco lights might be 1.5V.

From the DH126 manual:
9.3.4 Mars Lights On F1
To set up a Mars lights:
1. Wire lamp or LED to F1 and Blue Common
2. Program CV51 to 34
3. Mars light will be on when F1 is turned ON. This will make it non-
directional and ON whenever F1 is ON no matter which direction
the loco is running.
 

DakotaLove39

Always Improvising
Absolutely, yes. It is bit 0 of CV29. However, depending on which DCC control unit you have, many of them have a programming option for "loco" direction where you can just choose forward or reverse.
I do all of my programming at home on an NCE Powercab. My club, however, runs Digitrax. I have already encountered the snags common to locomotives travelling from NCE to Digitrax systems, and I'd prefer this being a permanent change that won't get lost between Home and Club.
 

Iron Horseman

Well-Known Member
I do all of my programming at home on an NCE Powercab. My club, however, runs Digitrax. I have already encountered the snags common to locomotives travelling from NCE to Digitrax systems, and I'd prefer this being a permanent change that won't get lost between Home and Club.
Unfortunately the Powercab is a system I do not have. I cannot advise or even comment on how it deals with the forward/reverse programming.
 

tootnkumin

Well-Known Member
Staff member
I.. already mentioned that.. yes.. Finding the CV is easy, I was just asking if permanent consisting in this manner is accepable or if it is prone to problems.
Sorry about that. No there's no problem with having them both running on the same address number, it's just like having a dual motor, dual decoder engine like Genesis's DDA40X, which is two seperate drives in one loco. The even have the decoders (Tsunami) so they go through the startup sequence, one after the other. I don't know how it's done but it's also possible to have engines in a consist producing the individual prime mover sounds, out of sync.

Unfortunately the Powercab is a system I do not have. I cannot advise or even comment on how it deals with the forward/reverse programming.
The Powercab can turn a loco around into the reverse position as part of it's Advanced Consisting program when setting up one such type of consist, simply by using the Reverse button whe asked which direction you want it to run, but because Steve wants to run both of these engines on the same address that's not a viable method. In the Programming options of the Cab, there are 3 choices, 1 for setting the long address, 2 for selecting the CV's you want to adjust, and 3 for config. In 3 Config, there is a part for changing/choosing the direction you want the loco to run when forward is pressed/selected on the cab. This comes in useful if a locos motor has been reverse wired by accident. Simply setting that Config to reverse will ensure the engine will go in reverse when the Cab command is forward. Now, so long as you only have the rearward facing loco being programmed on the track and answering to it's address, you should (disclaimer here cause I've never tried it) be able to then recombine it with the other front loco. The 2 decoders involved here should obey the commands given to each and theoretically obey how they each have been configured, even though running together. If the rear engine doesn't (and I've just written a lot of gobbledegook), then the only other recourse would be to rewire the motor wires on the decoder to the opposite connections.
 

tootnkumin

Well-Known Member
Staff member
Absolutely, yes. It is bit 0 of CV29. However, depending on which DCC control unit you have, many of them have a programming option for "loco" direction where you can just choose forward or reverse.

First check that the headlight is 12V because that is what the output of the decoder is. I think the loco lights might be 1.5V.

From the DH126 manual:
9.3.4 Mars Lights On F1
To set up a Mars lights:
1. Wire lamp or LED to F1 and Blue Common
2. Program CV51 to 34
3. Mars light will be on when F1 is turned ON. This will make it non-
directional and ON whenever F1 is ON no matter which direction
the loco is running.
I can see I was wrong about any standardisation of the f keys
 

bnsf971

Gomez Addams
Staff member
Yes, I already addressed this. I have tested both locos on separate loops but working as a DCC consist, and they perform indentically.

I'd rather not ever have to bother creating a system consist for these two as it strikes me as being a giant pain in the butt at the club layout. If #19A is being used, it's because #20B can't do the job alone. #19A will never be used alone.

I.. already mentioned that.. yes.. Finding the CV is easy, I was just asking if permanent consisting in this manner is accepable or if it is prone to problems.
I have several F unit pairs that I have addressed to the A unit's cab number. I just need to make sure they are both facing the same direction when operating each pair. With a pair of E's, you shouldn't have to be so much aware of it.
As for lighting, that should be in the cv 50-ish range. I have always used what seems to now be the ESU standard. That is, F5 is numberboards, F6 is Mars light.
 

DakotaLove39

Always Improvising
I want to give a quick response to say thanks for all of the input. my two E7's now operate as a pair, with one having it's CV for direction changed. BUT, during the process of doing this I discovered that my "B" loco is missing its front truck tower cap to hold the driveshaft down, so it's going to be a while before I can finally run these two together.

The accessory lighting still eludes me. I may have to re-wire everything together (or to a different decoder) in order to properly set that up. The factory lighting board offers zero help in telling me what's what. I wish every company would do as Athearn and ESU did with UP #1943's factory lighting board and LABEL the contact pads for which function they are.
 

NCRC5315

Member
It's been awhile since I've used JMRI, but I think, once it reads the CV's in the decoder, will show which output is what, and the program is free.
 

tootnkumin

Well-Known Member
Staff member
I want to give a quick response to say thanks for all of the input. my two E7's now operate as a pair, with one having it's CV for direction changed. BUT, during the process of doing this I discovered that my "B" loco is missing its front truck tower cap to hold the driveshaft down, so it's going to be a while before I can finally run these two together.

The accessory lighting still eludes me. I may have to re-wire everything together (or to a different decoder) in order to properly set that up. The factory lighting board offers zero help in telling me what's what. I wish every company would do as Athearn and ESU did with UP #1943's factory lighting board and LABEL the contact pads for which function they are.
I think I've only once wired a sound decoder to a lighting board, just seemed a waste of the decoders lighting capabilities of it's own and cluttering of an already confined space, with the old lighting board. Board type sound decoders usualy mark the wiring tabs on them with symbols or/and small writing like Front + - for the H/light. Rear + - for the tail light. M+ - for the motor and the F numbers on the accessories F5 F6 etc. The decoders with wires attached go by the color codes of the wires and they will be in the instructions that come with them. The one that might confuse you is the blue wire, or common wire. That always represents positive +. e.g. in the case of wiring an LED in place of a bulb, where, because LEDS are polarity sensitive, the + side is always attached to that blue wire and the negative with it's attendant resistor, goes to the F number that is being used to operate that LED light.

As far as operating the engine without that cover holding the gear in place, take the shaft and pinion worm out for now, the gears in the truck should rotate (check the wheels with your finger to make sure they will). The motor will still drive the other truck. Just don't loose the worm or the bearing blocks or any thin washers off each side of the worm. Store in a closed container marked for what it is.
 




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