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DCS Hints and Tips

The MTH Digital Command System (DCS) has provided a new high-water mark in the remote control of toy trains.  It is feature-rich and can provide great additional enjoyment when running your trains.  As with any sophisticated software system however, there are a few hints and tips that may not be immediately obvious but with which you can enhance your DCS experience.  On this page, I've compiled a series of hints and tips that you may find to be of use.  Note that these are not in chronological order and that, as new versions of the DCS software become available, any and all tips may be updated to reflect new facets of the system.

Tip #1

The basic DCS (Digital Command System) consists of a remote and a TIU (Track Interface Unit), which is the heart of the system.  The TIU sits between your voltage source(s) and the track.  On all four of its channels, it injects the DCS signal which controls MTH Protosound 2.0 locomotives.  On two of its channels it can also vary the voltage to control non-command locomotives.  One of the important things that you need to know about the original issue TIU (called rev. G) is that it does not have its own circuit breakers and depends on those in its voltage source(s).  If you are using an older transformer (such as a classic Lionel ZW) that has slow-acting mechanical circuit breakers, in the event of a short circuit there's a chance that the slow-acting breaker will not trip before the TIU (an electronic device) can be damaged.  For this reason, you will want to protect the TIU by placing a fast-acting fuse on the hot lead between the transformer and the TIU, as recommended by MTH.  Here's how to do it, in 12 easy, illustrated steps.

Step 1 -- Obtain a heavy-duty in-line fuse holder (Radio Shack #270-1217 or equivalent).  This is what it looks like when you take it out of the package.

Step 2 -- Cut the wire partway between the two ends of the fuse holder.

Step 3 -- Strip the ends of the wire.  Have a banana plug ready to be installed (Radio Shack #274-734A or equivalent) -- while you do not have to do this, it makes hooking things up to the TIU much easier.

Step 4 -- Insert one end of the stripped wire into the banana plug in preparation for soldering.

Step 5 -- Solder the wire to the plug.

Step 6 -- This is what it looks like after soldering.  Do not create a large mound of solder! Put the plug back into its insulated jacket.

Step 7 -- Prepare a 14 gauge wire with a spade lug on one end (to connect to the ZW) and strip the other end to connect to the fuse holder.

Step 8 -- Solder the end of the wire to the bare wire coming from the fuse holder.

Step 9 -- Insulate the soldered connection -- I use closed end insulating terminals.

Step 10 -- If using this kind of connector, crimp it closed for a snug fit.

Step 11 -- Insert a fuse in the fuse holder.  If you run long strings of lighted passenger cars with double-headed locomotives like me, use a 15A 32V fast-blow fuse (AGC-15 or equivalent); use a 10A 32V fast-blow fuse (AGC-10 or equivalent) if you don't.

Step 12 -- Connect the newly created patch cord between the TIU and the ZW.  Here's my TIU with all of the channels connected.

The second and subsequent issue TIUs, called rev. H1, I, and I3A (and so noted by a sticker on the bottom of the TIU) have an internal 20 amp fast-acting mini-blade fuse (automotive type) to protect each channel.  Since you have to open the TIU to replace any that may blow, I still recommend that you use the external fuse as shown above as it's much easier to replace an external fuse.  Also, the 15 amp external fuse will blow before the 20 amp internal fuse; 15 amps is generally more than enough for any single TIU channel.

Tip #2

The white cable that you see coming out of the left side of the TIU in the photo above is from an auxiliary power supply (Radio Shack #273-1690 with plug #273-1716 ) which powers the TIU independent of the track power.  Unless you have a single loop of track, this is a major convenience and is relatively inexpensive ($15.00).  This power source meets the requirements specified in the DCS Users' Manual.  Be sure to set the power supply to 18 volts.

Tip #3

To run Lionel's Trainmaster Command Control (TMCC) with DCS, you need a special cable to connect the TIU to the TMCC command base (MTH #50-1018).  I recommend strongly that you use this special cable and not try to build your own.

Tip #4

When running command-mode locomotives on the Variable 1 and/or Variable 2 channels of the TIU (those channels that can be used for both command and conventional operation), you first have to turn on your voltage source(s) to those channel(s), then you have to hit the TR (track) button on the remote, select which track you want to use, and then dial up the voltage!  When you have the voltage set where you want (usually between 18 and 22 "volts", but keep reading), THEN you can address your command-equipped locomotive in command mode.  Always remember to dial off the voltage when you are finished.  Speaking about dialing in the voltage, the number you see is not actually the voltage but rather a representation of it.  If you have not changed the defaults in the remote, it's set to go from 0 volts to 5.0 "volts", to 5.5 "volts", etc., up to 22 "volts".  The number you see on the remote is actually that number of twenty-seconds of the voltage that you have on the channel input.  For example, if you have your transformer set to put 18 volts into Variable 1 and you dial in 18 "volts" on the remote, the voltage on the track is actually 18*(18/22) or 14.7 volts.  So, if you want to have the voltage that you're feeding into the channel actually be present on the track, you need to dial in 22 "volts" on the remote for that track.  In that way, whatever you put in is what you get out (making the Variable channel function like one of the Fixed channels). Starting with v.2.10 of the DCS software , you can set your Variable channels to act like Fixed channels (if you're running command-mode locomotives) -- go to MENU, SYSTEM, DCS, scroll to the Variable channel and hit the FXD softkey.  This will make the Variable channel act like a Fixed channel so that you don't have to dial in the voltage when running in command-mode. Whatever you put into the channel from your transformer will be passed through to the track.

Tip #5

If you have a large layout, with tracks that interconnect with crossovers and you power your layout using multiple TIUs, you may run into a situation where your PS2 locomotive moves from a track controlled by one TIU to a track controlled by another.  In that case, you may lose control of your locomotive, as DCS thinks it's still addressed by the first TIU.  The way to deal with this problem is to go into MENU, SYSTEM, TIU, SUPER TIU, and set "super" mode on each of your TIUs.  This will allow you to maintain control of your locomotive even when it moves between tracks controlled by different TIUs.  Note that this results in increased communications overhead, so unless your layout has this situation, do not use the Super TIU setting.  Also be aware that if you use multiple remotes, each remote must also be set, as above, so that it knows that each TIU is in super mode.  Also see Tip #11, below, for more information about SuperTIU mode.

Tip #6

When adding PS2 locomotives to your remote, very occasionally (due to signal strength problems, phases of the moon, etc.) the locomotive will add "wrong." By this I mean that it may add with an incorrect of blank name, or even if it has the correct name, many of the softkeys will be wrong, the list of "more" commands will be very short, etc.  The easy way (and the only way) to deal with this problem is to delete the locomotive from the remote and then re-add it.  If it adds incorrectly a second time, move the locomotive to a different spot on the track and try again.

Tip #7

When controlling a PS2 locomotive with the remote, you have a set of five softkeys showing four functions plus a right arrow.  To see more functions, press the right arrow.  The softkey functions scroll so that you have a total of 15 commands via the softkeys.  There are more commands, but you have to access them from the "MORE" screen, which you get to by pressing the MOR softkey (you may have to scroll with the right arrow to see it).  If you look at the list, you'll find that the first 15 are the ones that appear on the softkeys.  If there's a MORE function that you'd prefer to have available via the softkeys instead of one that's already there, you can move that selection up so that it's in the top 15.  When in the MORE list, point at the selection you want to move, hit the MOVE softkey, and using the thumbwheel, move the selection up into the top 15; press the thumbwheel to "drop" the selection there (recognizing that the 15th selection will now become the 16th and no longer available via the softkeys).  You can also reorder the softkeys that do appear by rearranging the MORE functions; e.g., my locomotives show SCS (coupler slack), SFS (forward signal), and SRS (reverse signal) as their first three softkeys since I've rearranged them.  REMEMBER: the softkeys are on a per-locomotive basis, so changes you make apply ONLY to the locomotive that you're currently controlling. Also, the changes are stored in the remote that you're using; if you switch to a different remote, the softkeys will appear in the factory default order (until you rearrange them again).

Tip #8

With DCS, you have the capability of updating your system with software downloads available at the Protosound 2 web site.  There are a few things to remember before attempting a software update:

Tip #9

Here are the softkeys that appear when you use the TR key to access the TRACK menu and select one of the variable tracks to control (these were accidentally left out of the DCS Users' Manual):

I hope this list is helpful

Tip #10

MTH has acknowledged a problem in using early Protosound locomotives manufactured in 1995 and 1996 with DCS.  Those locomotives were designed to detect an electronic power source (with a shark fin waveform that could cause PS1 to malfunction) and refuse to run if they found one. Unfortunately, though they run just fine with DCS, when you first put voltage on a variable channel, they read it as an electronic power source and refuse to run.  Here's how to work around it:

Also see Tip #12, below.

Tip #11

In Tip #5 up above, we mentioned SuperTIU mode, which enables you to control locomotives across multiple TIUs on your layout.  Here is some additional information that will help you to enjoy this feature if your layout can make use of it.  First, when using SuperTIU mode, all of the locomotives should be added to a single TIU to keep things from getting confused down the road. In addition, it has been discovered that all locomotives should be added to that TIU when it's NOT in SuperTIU mode; i.e., if you're operating in SuperTIU mode, switch back to normal mode before adding locomotives, add them on a channel controlled by that single TIU, then switch back to SuperTIU mode for operation (this is at v.2.10 of the software and may be addressed in a future revision). Once all of the locomotives have been added and you're back in SuperTIU mode, you can proceed to create your lashup.

Tip #12

On 09 Sep 2002, MTH released v.2.2 of the DCS software.  In response to the early PS1 startup problem mentioned in Tip #10, above, they have provided a new softkey, PS1, in the TRack softkeys.  With the variable track set to variable mode and zero volts, hitting this softkey starts up the early PS1 locomotives without any problem at all.  This softkey is in all subsequent versions of DCS.

Tip #13

MTH has finally documented all of the various keys that are used in "trolley mode" (the station stop mode that is present in the various PS2 trolleys and subway sets).  Here is the explanation of how trolley mode works and what all of the keys are about.

Trolley Mode Automatic Operation

For automatic mode behavior, specific station stops and distances between them can be programmed and saved. The process for this, or "learn" mode is outlined in the following steps.

1. The user presses MLM to enter "learn" mode

2. The trolley is driven to the track location for where the first stop will be stored

3. The user will select the specific stop to be programmed using the LST softkey

4. The stop will be saved by pressing the SAV softkey

5. Steps 2-4 are repeated for the remaining stops to be programmed. Stops must be stored in sequence as is required in conventional mode. Interim stops are removed from availability in the stop list.

6. After the last stop is programmed, the sequence is saved as either out and back (OAB) or loop by pressing a softkey. For OAB, the user simply saves the sequence at the last programmed stop prior to moving the trolley (by either pressing SAV twice or pressing the SOB softkey). For loop, the trolley must be moved in the forward direction back to the original point of origin and saved as a loop (SLP softkey or SAV after pressing LST and sounding the first station again).

The user can toggle in and out of "automatic mode" via a softkey. This key will simulate the B-W-W command used to enter and exit automatic behavior similar to the B-W-W command in conventional mode. NOTE – If the user toggles back into Auto mode from Manual mode they will have to drive the engine to the first station saved during Learn mode and ensure the engine is in the correct directional state (Forward or Reverse).

While operating in automatic mode, the user can toggle between "all stops" and "random stops" via the FAR softkey.

Trolley Mode Manual Operation

In "manual mode" the user will initiate a stop sound sequence through the following method:

Press the MMM softkey to enter the Manual Mode Menu. Press the FSS softkey to announce the next stop. Every press of the FSS softkey will play the next available station announcement. Once the desired stop announcement has been made, the system is armed and will play the sound sequence for the selected stop the next time the trolley reaches ZV. When the engine departs that station the announcement for the next station will be made automatically. If the user wishes the engine to stop at this station press the ARM softkey. If the user does not wish to stop at this station then press the FSS softkey until the appropriate station announcement is called.

Once a specific stop is selected, subsequent stop selections override the previous one. Therefore, the user can select a specific stop and then change this request simply by selecting a different stop by pressing the FSS softkey.

Once a stop sequence is saved as a loop, the user can toggle between OAB and loop behavior via the FOL softkey.

Trolley Mode Key Chart




Specific Stop(s)


One of "n" number of stops that can be specifically selected by the user. These commands are also used in learn mode to program stops.

Auto Mode


Toggles trolley between auto and manual mode

Learn Mode


Initiates learn mode

Save OAB


Saves programmed stop sequence as OAB

Save Loop


Saves programmed stop sequence as loop



Toggles behavior between OAB and loop in auto mode



Toggles behavior between OAB and loop in auto mode

Manual Mode


Enter Manual Mode

Arm Next Stop


Arms the next announced stop when departing the current stop

Tip #14

With multiple versions of DCS now available (as with most software), it's sometimes hard to remember what changed with which version.  Here's a page that documents what showed up with which version.  This is kept updated for all releases of DCS.

DCS Revision History

Tip #15

MTH has begun to post sound files on their web site, opening the possibility of changing the sound files in your PS2 locomotives.  There are some things that you need to be aware of, however, before you attempt this.  The 'sound' file is more than a sound file. It also contains information specific to the locomotive; e.g., the gear ratios that relate the revolutions of the timing tape to the actual revolutions of the drivers.  If you put a sound file intended for one type of locomotive into another, that locomotive may not work properly!  If you're going from similar to similar (e.g., the gray F-E-F to the black F-E-F) there should be no problem; if you're going from a Challenger to an 0-6-0 switcher, you may well wind up with a locomotive that does not work properly.  BACK UP THE EXISTING SOUND FILE BEFORE YOU TRY LOADING A NEW ONE!  If you manage to screw up the operation of your locomotive, you can then put back the old one to restore proper operation.

Tip #16

This tip is for those who use multiple TIUs on their layout.  There are basically two types of operation when you have more than one TIU – you can have trains actively moving between regions of your layout that are controlled by different TIUs or you can be running trains that are on tracks controlled by discrete TIUs.  If you’re in the former category, you’re probably using Super mode and this tip is not for you.  If you’re in the latter category, however …

 As you probably know, DCS knows with which TIU a locomotive was added and sends commands for that locomotive only to that TIU.  If you transplant a locomotive from, say, a loop controlled by TIU #1 to a loop controlled by TIU #2, you will get “Check Track” errors when you try to address it since the commands are still going to TIU #1 (which of course can’t find it).  While you could run in Super mode, or could delete the locomotive from the remote and re-add it on the current TIU, there’s a much quicker and easier way!  All you need do is hit the READ button!   When you do a READ, if you’ve moved a locomotive from TIU #1 to TIU #2, this is recognized and the TIU association is changed accordingly.  In a situation such as mine, where two loops are controlled by TIU #1 and two loops are controlled by TIU #2, it’s a very quick, painless, and ideal way of moving trains around on the layout without worrying about which TIU is which.

Tip #17

On the first production run of DCS, the foam on the cover of the battery compartment of the remote was positioned toward one end.  This sometimes allows the batteries to dislodge if you put the remote down with a little more force than normal.  The easy fix is to put some additional foam (I use some self-stick weatherstripping in the appropriate thickness) at the other end of the cover.  This ensures that the batteries stay in place.

Tip #18

There are two advanced features of DCS that give you tremendous control over how your locomotives behave -- ACC RATE (acceleration) and DEC RATE (deceleration).  You access these from MENU, CONTROL.  The settings range from 0 to 25 for each.  If you set ACC RATE low, as you scroll your thumbwheel to increase the speed, the increase will be quite slow.  If you set it high, response to the thumbwheel will markedly increase.  The same holds true for the behavior of the train when it's coming out of PFA -- if it's set low, the train will slowly accelerate from stop.  If it's set high, the train will take off.  With DEC RATE, if you set it low, as you decrease speed with the thumbwheel, the decrease in speed will be gradual.  If you set it high, the decrease can be quite sudden.  When you hit DIR, if the DEC RATE is low, the train will slowly coast to a halt.  If DEC RATE is high, the train can quite literally stop on a dime and, possibly, derail some cars.  As of v.3.00 of the DCS software, these settings also affect the Boost and Brake functions -- whatever you set will become the increment for the Boost or Brake.  For example, if you set DEC RATE to 5 and then hold down the brake button when your train is running, the speed will decrease initially by 5 smph, then 10 smph, etc.

Tip #19

If you are using one of the small MTH transformers (Z-500, Z-750, or Z-1000) you have two parts to your transformer -- a power brick that plugs into the wall (the transformer itself) and a small box with a knob and a few buttons on it (the controller) into which you plug the brick.  If you are going to hook one of these up to DCS, you need to know that you  use only the brick and NOT the controller.  MTH sells a barrel jack adapter (part #50-1017) that will let you plug your transformer directly into a TIU channel.  The same holds true if you have one of the IR "remote control" transformers that came with older MTH starter sets.  You use only the brick and not the IR lockon.

Tip #20

When performing the DCS software update from v.2.x (any prior version) to v.3.x (any version beginning at v.3.00), you MUST perform either a feature reset (preserve TIU address) or a factory reset (reset TIU address to #1) on the TIU and a reset on the remote after installing v.3.x.  Version 3.00 introduces a new restructuring of memory with all user information now stored in the remote.  Performing the reset after installing the new version ensures that memory in both components is cleared and restructured so that the v.3.x software works properly.  Failure to do so can result in some very strange behavior.

Tip #21

No longer applicable.

Tip #22

Doing an upgrade of a PS1 locomotive to PS2 and wondering what sound files you can use?  In order to have the scale speed match your other PS2 locomotives, you need to match the driver size and gearing.  Sound hard?  Here's an easy way to find a compatible sound file -- find the locomotive you're upgrading on the traction tire chart!  Any of the other locomotives that use that same traction tire size should have a sound file that works relatively well.  Remember to match up the voltage!  Upgrades are all 3V systems -- don't try to load a sound file for a 5V locomotive into your newly upgraded locomotive!

Tip #23

I was asked by the folks at the Standard Gauge Module Association if I could provide them with useful information about running DCS with a modular layout.  I developed a document that I sent to them that distills my experience in demonstrating and using DCS with modules.  That document is available in .PDF format HERE.

Tip #24

I call this the "Palsied Finger" tip.    When doing a DCS software update and updating the remote, you need to hold the power button for about six minutes while it uploads.  Even though there isn't much tension in the button, by the time the update is finished, your finger is trembling and ready to fall off.  There's a much easier way that's a lot easier on your finger.  I would have thought that this was just plain common sense but giving the whining about it in online forums, apparently common sense isn't all that common these days.  Put your remote at the edge of your desk, or, if the edge of your desk is flush as mine is, use a piece of wood or plywood, stick it off the edge of the desk, and use a small clamp to hold down the button at the appropriate time!  How simple can you get?  For those who prefer pictures, here's a picture.

DCS remote software upgrade

Tip #25

With v.4.00 of DCS, a number of very handy new features were introduced.  Here are a few of the ones that I find very useful:

There are lots more new features which are documented on the DCS Revision History page.

Tip #26

With the introduction of Protosound 3.0 (PS3), a number of changes from Protosound 2.0 (PS2) have taken place.  Here, in no particular order, are some of the more noticeable ones.  This list is by no means comprehensive!

Last updated: 24 Feb 2023

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