This article discusses specific hardware-- ESU decoders and the Digitrax DSC51 Command Station --intended to be used in specific configurations.
My interest in this is for Japanese trains, where electric locomotives are sometimes consisted with diesel (or steam) locomotives to cover areas that don't have catenary for electric trains. That's obviously not a problem for toy trains, but it does make things interesting from a collecting and tinkering perspective.
I use 2-digit short addresses because they're faster to enter and easier for me to remember. I forget locomotive numbers, and they're usually too tiny to read on the locomotive. If I ever need more than 2 digits to identify my locomotives, then I've got waaaay too many.
Before, when I had a locomotive and a sound car that needed to run together, I'd just give them the same address. The Rheingold coaches always ran with the BR-18.5, the Nagomi coaches always ran with the E655. Just select the address in the controller and go. Easy. Simple. I believe this is referred to as Basic Consisting.
Once I got multiple locomotives to haul two sets of passenger coaches with sound cars, I had too many choice combinations. Basic Consisting didn't work very well for this. Although I could still change the addresses of all the decoders that needed to work together, it would be a hassle to haul each one, one at a time, to a programming track to change their addresses. I wanted a quick, easy and flexible way to change locomotive and sound car assigments. The other options were Universal Consisting and Advanced Consisting.
Universal Consisting: (I didn't pursue this deeply, and there's plenty of info out there if you're interested.) The Digitrax manual devotes several pages to Universal Consisting ("MU"), where their Command Station keeps track of the addresses in the consist. With the Zephyr, you can add up to four decoders (locomotives) to a consist. Programming in the Zephyr system is anything but intuitive and involves lots of keypress sequences. I tried, and my "successful" attempt resulted in the locomotives running in opposite directions, despite running in the same direction before consisting (as the manual instructed). There were brief moments of quirky behavior (one of the locomotives lurching), necessitating several system resets. Not very confidence inspiring. I wanted a procedure that was more intuitive and reliable. I didn't want the procedure to rely on the Zephyr to do anything too fancy or ambitious.
Advanced Consisting: Advanced Consisting relies on the decoder to do the main part of the work. ESU decoders support Advanced Consisting and the Digitrax Zephyr handles it without problems.
In the LokProgrammer's interface, you can turn on Advanced Consisting by entering a 2-digit secondary address, reverse the running direction if necessary, and select which function keys (F0 - F15) you want to enable (or not enable) for that secondary address. Any functions not assigned can be triggered by a separate throttle set to the primary address, but the keys assigned to the secondary address can only be triggered by the throttle controlling the consist.
The secondary address in CV19 overrides the decoder's primary address in CV1; if any address (except zero) is in the secondary address, the decoder won't respond to drive commands sent to the primary address. However, all decoders with the same secondary address will respond to drive commands sent to that address...and decoders with the same primary address, but without an secondary address assignment will respond to commands sent to that address. That's often mentioned as a potential source of trouble if you use 2-digit primary addresses and don't remember which ones you've assigned (just keep track of your addresses!). It can actually be a useful feature because 2-digit primary address decoders respond to the full set of function keys (F0-F27).
Therefore, you can set up two sound cars with different primary addresses and temporarily (or permanently) assign locomotives to them by putting the sound car's address into a locomotive's secondary address. If you set the locomotive's secondary address back to zero, the locomotive can be controlled by sending commands to its primary address.
This seems more intuitive and simpler than Universal Consisting: It's just changing the contents of a CV. To do this using the Zephyr Command Station, select a locomotive by its primary address, change CV19 to the address of the sound car, and select the address of the sound car to run the train. Here's the button-by-button for changing CVs in the Zephyr:
What makes this easier than Basic Consisting is that you don't have to move the locomotive to a separate programming track to change its primary address (if you didn't, the change would be made to all decoders with the same address). Through "Ops" programming, you can target a specific locomotive on the track by its primary address and change the value in CV19 without affecting the primary address. With this method, the locomotives retain their primary addresses so you can independently target and assign them to consists. (If decoders are always set up to run together, Basic Consisting --assigning them the same primary address-- is intuitive and works well.)
Consisting Scenarios: There are various scenarios for using consisting, listed from easiest to most challenging:
Advanced Consisting is a flexible solution for all these situations. In my case, for example:
Because the two sound car/coach sets have different primary addresses, both can run on the track at the same time with different mixes of locomotives consisted to them. (With Basic Consisting, a solution might be to give everything the same primary address and running either of the coach sets and some locomotives on the track at the same time.)
Since the sound cars are ID'd only by their primary addresses, all function mapping options work (F0-F28)-- useful if you want to trigger lots of sounds. The consisted motor decoders have fewer trigger-able features, so the consisted address limit of F0-F15 is more than adequate.
Matching Locomotive Drive Behavior: Model trains work best when pulled by a single locomotive. The most reliable performance of two or more locomotives in a consist comes from using dummy locomotives-- a single motor car pulling unpowered cars that look like locomotives. Multiple motors turning traction tires are more likely to work against each other than to work together to improve pulling power. That said, you're not likely to remove motors or traction tires from working locomotives just to use them with other locomotives in a consist.
This is the hardest part of consisting. With any form of consisting (Basic, Universal, Advanced) involving two or more locomotives, the drive characteristics of the locomotives should be fairly closely matched, with the lead locomotive being slightly faster than the one behind, throughout the entire speed range. When the second locomotive pushes the first, the movement can be jerky and erratic and can cause trucks to skew and hop rails, causing derailments.
Matching drive behavior involves tweaking the speed curves, the acceleration/deceleration curves, and the Load Control/Back EMF. Since identical motors can differ in subtle ways, having identical decoder settings often doesn't work. Adjustments may require lots of trial and error tweaking. (I'm not proposing my settings above as an example of a well-tuned locomotive: It's just where the numbers ended up for this particular locomotive when I was finally satisified/tired.)
I blundered my way through this by running the two locomotives on the same track, uncoupled, and set to the same address. I went through the entire speed range to see how the speeds differed in different areas of the curve and adjusted the motor curve of one to get a fairly close match with the other. I was satisfied if the rear loco generally kept up and didn't slam into the front loco, or didn't fall far behind. Once they were close, I coupled them together and observed how they reacted throughout the entire speed range.
Using Load Control/Back EMF can cause problems, especially if more than one locomotive has it turned on-- they may fight against each other while trying to compensate for the changing load. However, some locomotives may need Load Control when they aren't part of the consist... and it would be a hassle to juggle two different configurations just to use consists. Hopefully, you can find the right mix of parameters (including Regulation Influence) that will work in both situations.
I quickly learned that Load Control parameters and the Motor Curve interact with each other... undoing all your work tweaking the motor curve. Also, some motors do not act the same going in reverse. They also act differently once they've been warmed up. That's why "Close 'nuff for gubment work" is a good motto to go by when speed matching. (Otherwise, you'll drive yourself insane.)
Assignment of Function Keys: When mixing sound decoder locomotives with sound cars in a consist, the assignment of function keys will take some planning. For example, I initally set up these coach sets/sound cars with electric and diesel drive sounds on F1 and F5, respectively. As a general practice, I use F1 to start up drives sounds regardless of the type of locomotive. This posed a problem if a sound-equipped steam and non-sound diesel locomotives were consisted with the sound car: F1 turned on the drive sound in the steamer and the electric drive sound in the sound car (not a problem if the consist has an electric locomotive). A solution would be to consistently reserve three function keys for each of these types of drive sounds. However, for locomotives with a sound decoder, this would waste two of the function keys just so it could operate in the sound car consist. I discuss my solution in greater detail in "Sound Function Mapping", below.
Ideally, each locomotive would have its own onboard sound decoder with its own unique sound set. Of course, if you could fit a decoder and speaker into every locomotive, you wouldn't need sound cars, or generic types of drive sounds. Even then, this wouldn't solve the problem of function keys assignments in consists (unless you had a throttle for the consist speed and separate function key controllers for each of the sound locomotives). Unfortunately, N-scale does have its limitations and challenges...
Couplers: Grrrr... arghhhh! This is just an unwelcome complication in something that's already complicated enough. If you've got different coupler types in a train, you may have to make adjustments when swapping locomotives. For example, Kato's Orient Express coaches are equipped with Rapido couplers, but the Imperial train coaches are equipped with Kato's knuckle couplers. Kato's locomotives usually come with both types so you can hook them up to a particular train. It can be an annoyance when you're consisting locomotives that have Rapidos on one end and knuckles at the other, but they're on the wrong ends.
Video Clip: D51 with onboard Loksound consisted with EF58 and sound car using Advanced Consisting. The challenge is coming up with a scheme for organizing and mapping function keys that works for different scenarios.
The D51 steam locomotive's function keys are set up using a scheme loosely based on function key assignments in my first DCC sound loco, the Fleischmann BR01-10 with Zimo decoder. I followed that basic pattern in all my sound decoders so I could remember what buttons to press. These don't conform to the layout that Digitech proposes and what most people probably use. For example, I use F0 for lights, F1 to start the loco drive sound, F2 & F3 for horn sounds, F4 for rail clanks, F6 for crossing sound/acceleration/shunting mode, F7 for brake squeal, and F8 for station announcements. F5 and F9 are for sounds like fans, compressors, coal shoveling, etc. For a sound decoder tied to a single specific locomotive, F10-F27 are available for those miscellaneous sounds.
A LokPilot decoder (motor and sound) uses very few function keys: I use F0 for lights and F6 for acceleration/shunting mode. This matches the assignments in the LokSound since they're usually consisted together in a locomotive/sound car pair.
This scheme works well with the Digitrax DCS-51 Zephyr Command Station. The Zephyr has 10 numbered function keys (0-9), and buttons for +10 and +20 to access the additional function keys. I think of those as "bank select" buttons (similar to the concept used in electric guitar multi-fx floorboards). Of course, it would be better if throttles had 28 function keys, but none do and the Zephyr's layout requires a minimum number of button presses to trigger functions across the three banks.
For a LokSound decoder used with a specific locomotive (like the D51) in "Primary Address Mode", all the most commonly used sounds/functions are available in bank 0, F0 - F9. The extra sounds are available in F10-F27.
When used in "Secondary Address Mode" (Advanced consisting) to be used with a sound car (and other locomotives), only a handful of function assignments are enabled: F0 (lights), F1 (drive sound), F2 (horn), F4 (rail clank), F5 (misc. sound), F6 (crossing sound/acceleration/shunting), F7 (brake squeal) and F9 (misc. sound).
I divide the sound car decoder's function map into banks that match the Zephyr's button layout. Bank 0 (F0-F9) is set up with commonly used sounds/functions, minus F1 (drive sound), F2/F3 (horn sounds), F5/F9 (misc. sounds). This way, pressing F1 starts up the drive sound for the consisted locomotive with sound decoder (the D51). I tried to add a steam drive sound (3rd drive sound) to the sound car's decoder, but I think that exceeded the decoder's capabilities.
Bank 1 (F10-F19) is set up for an electric locomotive. F11 is mapped to the drive sound, F12 and F13 are horn sounds. This corresponds to the same keys (1, 2, and 3) used for the same functions in Bank 0. All other keys in the bank are available for miscellaneous sounds, although I avoid assigning sounds to keys 4, 6, and 7. This makes the assignments consistent without duplication. For example, if you put "rail clank" on key 4 of bank 1 and turn it on, pressing key 4 in bank 0 won't turn the sound off. That could get very confusing!
Bank 2 (F20-F27) is set up for a diesel locomotive, using the same concept.
I should reiterate that I came up with this so I could assign different locomotives to my Imperial and Orient Express coaches and their sound cars. I expect to have five locomotives to juggle: the D51 steamer, the EF58 electric, the DD54 diesel... plus an EF81 electric and DD51 diesel. The sound cars are therefore a generic solution for types of locomotives. That's okay by me because I'm not that fussy.
The D51 steamer with onboard sound decoder is an oddity that I needed to accommodate. It's my only Japanese steamer, and I haven't installed a sound decoder in any of my other (German) steamers. I guess I'm fortunate that it worked out this way because I couldn't install a 3rd steam drive sound in the decoders-- that would have let me consist the German steamers and give them sound. I'm not entirely satisfied with this though because the D51 didn't have enough room to install a good speaker; consequently, it doesn't sound nearly as good as the German steamers with their dedicated sound cars.
Before I knew anything about consisting, I thought it would be a simple matter of learning the Command Station's button-pressing sequence. Unfortunately, it's more complicated than that. The majority of the work is speed matching locomotives that will be consisted together (not an issue with consisting sound cars). On the glass-half-full side, it does give you a reason to fiddle with all those baffling decoder parameters that you probably never found a reason to tweak. Once everything's figured out and configured, the act of consisting is relatively quick and painless, and can be done on the fly - which is how it should be. However, to get there may take hours of trial-and-error tweaking of your locomotives.