Consisting Tsunami Decoders on the Lenz Digital Plus System

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This article explains some subtle issues which can arise when using Advanced Consisting with Soundtraxx Tsunami sound decoders on a Lenz DCC system.

Note: Lenz may call their version of Advanced Consisting MU Consisting or Smart Consisting.

The Tsunami sound decoder is one of the few decoders available which provides a simulated braking feature, activated by a DCC function. If using the Tsunami brake feature to actually slow the train down, as well as activating the brake squeal sound, it is obviously important for all locos in a consist to receive and respond to the brake command simultaneously. (The same braking feature is also available in the Soundtraxx MC1 and MC2 non-sound mobile decoders.)

Lenz may refer to Advanced Consisting as Smart Consisting although, as will be explained later, the two terms are not directly equivalent. Lenz Smart Consisting requires that the loco decoders support Advanced Consisting, but loco decoders which support Advanced Consisting will work in a consist on a Lenz system with or without Lenz Smart Consisting.

This article is based on a Lenz system with version 3.5 firmware. Based on published information regarding the Version 3.6 Update, the information is also applicable to that version.

Although this article deals primarily with Lenz DCC, many aspects will also be applicable to other DCC systems.

How Lenz Handles Smart Consisting

There are, at least, five ways of creating an MU Consist to operate on a Lenz system:

  1. Following the procedure "Assembling a multi-unit consist (MU)" from the Lenz LH100 manual
  2. Manually editing CV19 and other CV's using Programming on the Main (PoM)
  3. Using computer software such as JMRI or WiThrottle
  4. Manually editing CV19 and other CV's on the programming track
  5. Creating the consist on another layout or DCC system, i.e. a so-called "portable" consist

The Lenz system handles the consist differently, depending on which of the above methods is used to create the consist.

For method 1, 2 or 3 above, the Lenz system is "aware" of the consist and operates as follows:

  • The speed and direction of the consist can be controlled from either the 2-digit consist address, or from the individual address of any of the locos in the consist.
  • If using an LH100 throttle, the throttle displays a capital "M" when the consist address is selected and a lower case "m" when the address of any loco in the consist is selected.
  • When using the consist address ("M"), the function keys on the throttle do not operate and it is not possible to control any of the functions for any of the locos.
  • When using the address of a loco in the consist ("m"), the function keys on the throttle control the functions for the selected loco only. To control functions for other locos in the consist, it is necessary to first select the individual loso address on the throttle. (The "-" button can be used to scroll through the addresses for the locos in a consist as well as the overall consist address - see the LH100 manual for details.)
  • Because a loco in a consist no longer responds to speed and direction commands sent to its individual address, the Lenz system redirects speed and direction commands to the consist address when an individual loco address is selected on the throttle. However, the Lenz system still sends function commands to the individual loco address.

For method 4 or 5 above, the Lenz system is "unaware" of the consist and operates as follows:

  • The speed and direction of the consist can only be controlled from the 2-digit consist address. (Note that the locos no longer respond to speed and direction commands sent to their individual address when in a consist.)
  • The LH100 throttle does not display any special characters to indicate that a consist is being controlled. The LH100 displays shows "E" (for Engine - assuming English language selected) in front of the loco number. As far as the Lenz system is concerned, it is simply controlling a normal loco with a 2-digit address.
  • Loco functions can be controlled by entering the individual loco address on the throttle but speed and direction cannot be controlled.
  • For decoders which support CV21 and CV22, loco functions can be controlled via the consist address and both locos will respond simultaneously to the same function button if so configured via CV21 and CV22.

The first scenario described above, in which the Lenz system is "aware" of the consist is actually Lenz Smart Consisting and it should work fairly well for most people. To just control loco functions such as lights and horn, most people would be happy to have these functions apply to the lead loco only, in which case it make sense to "drive" the consist by selecting the address of the lead loco on the throttle.

Limitations of Lenz Smart Consisting

However, there are a number of scenarios under which the Lenz Smart Consisting will not be satisfactory:

  • If the consist was created on another layout or by modifying CV19 on the programming track, the Lenz system will only allow the consist to be "driven" using the consist address, but loco functions cannot be controlled. This may be satisfactory for a non-sound loco, as the lights could potentially be turned on prior to moving the consist using the address of the lead loco, them the throttle changed to select the consist address for actually driving the train.
  • If it is desired to send function commands simultaneously to all locos in the consist, such as the brake function available in the Tsunami decoder. Another example would be the sound "mute" function.

DCC Advanced Consisting without Lenz Smart Consisting

Provided the loco decoders support Advanced Consisting in accordance with DCC standards, consisting will work without using the Lenz Smart Consisting feature and, in fact, this offers some advantages:

  • Consists can be used which have been created on another layout or by modifying CV19 on the programming track.
  • Function commands can be sent to multiple locos simultaneously, by setting the throttle to the 2-digit consist address.
  • The behaviour of individual locos in response to function commands can be configured using CV21 and CV22, provided the decoders supports these CV's. This can be used, for instance, to ensure that the headlight function only operates the headlight on the lead loco, and not the headlights on the other locos in the consist.

But there is a Gotcha!

If you set up an advanced consist by altering CV19 on the programming track, you will probably find that the loco's horn sounds repeatedly, and/or the headlight flashes slowly under some circumstances.

In fact, this strange behaviour is due to the "refresh" feature for function commands. The Lenz system (and most other DCC systems) repeatdly sends out function commands to all locos in the current "stack", even when there has been no specific user command to change the state of a function. The intent of this is to make sure that lights and other loco functions are restored to their intended state when the layout is first switched on or after an interruption to track power.

With Lenz 3.5 systems, the refresh feature only applies to F0-F4. With Lenz 3.6 systems, the refresh feature is extended to higher number functions or optionally restricted to F0-F4 if desired.

The consequence of the refresh feature is that the Lenz system may be sending the same function command twice to the same loco, once via the consist address and once via the individual loco address. For instance, if the headlight was off the last time the loco was driven via its individudal address, and switched on when it is being driven via the consist address, the decoder will receive conflicting OFF-ON-OFF-ON commands as the Lenz system continually refreshes the functions for all locos in the stack. The same applies to the horn function.

If the consist was created on another layout and the locos in the consist have never been operated on the current layout, then the individual loco address will not be in the stack, and the "gotcha" doesn't apply.

There is a Workaround

The workaround is to delete the individual loco address from the stack, once the consist has been setup. This is a simple procedure and is detailed in the LH100 manual under "SET 5: Erasing locomotive addresses from the command station stack".

Once the corresponding loco addresses are removed from the stack, the Lenz system will no longer send conflicting function commands to the locos in the consist and the functions can be controlled from the consist address.

Note that any attempt to drive a loco or activate any functions via its individual address will result in the loco address being added to the stack again. Somewhat surprisingly, selecting the individual address of a loco while in a consist to make a CV change via PoM does NOT cause the address to be added to the stack. This can be useful for fine tuning the CV21 and CV22 values once the consist has been set up.

CV21 and CV22 Configuration

As mentioned above, the various bits in CV21 and CV22 determine which functions are active for that particular loco when in a consist. The bit allocations are defined by the NMRA DCC standards and also detailed in manuals for decoders which support CV21 and CV22, including Tsunami.

If the end locos in the consist are facing in opposite directions, and the front and rear lights are configured for independent control, the lights will not work correctly, irrespective of the CV22 setting, without further adjustments to the locos' function mapping. This is because the rear light function for the consist needs to operate the front light on the rear-facing loco. This combination is not achievable by adjusting CV22 alone.

Function Swapping

There is a trick, however, if using the Tsunami "Function Swapping" feature (CV30 = 4), which swaps the function groups F5-F8 and F9-F12 to provide more flexibility in function mapping. If using function swapping, the bits in CV21 and CV22 must refer to the original "unswapped" functions.

For example, if using F5 to control the brake, the bit corresponding to F9 must be set in CV22, because the brake feature is internally mapped to F9 and "swapped" to allow activation by F5.

Similarly, if using F8 for mute, the bit corresponding to F12 must be set in CV22.


  1. Avoid using Lenz Smart Consisting if you need to be able to simultaneously control functions in multiple locos in the consist.
  2. To avoid using Lenz Smart Consisting, configure the required loco CV's (e.g. CV19, CV21, CV22, etc.) on the programming track or on another layout.
  3. After confirming that the consist can be driven on the layout using the consist address, delete the individual loco address from the Lenz stack (if present).
  4. Avoid driving or operating functions using individual loco address while they are in the consist, or the address will be added back onto the stack. Use only the 2-digit consist address for driving the consist or operating functions.
  5. If you must activate a function on an individual loco, such as turning off an unwanted light, select its individual address on the throttle, activate the desired function then, after selecting some other address on the throttle, remove the individual loco address from the stack.
  6. If necessary, adjust CV21 and CV22 to fine tune the operation of function on individual locos in the consist. This can be done without adding the loco addresses back onto the stack.
  7. Have fun driving your consist.
  8. To remove one or all locos from the consist, select the individual loco address on the throttle and use PoM to set CV19 to zero. The loco will then respond to its individual address rather than the consist address.

See Also

DCC Manuals

General Consisting Information

Other Tsunami Information