Advanced Consisting, Lenz and Soundtraxx Tsunami Multifunction Decoders

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Summary: This article explains the subtle Advanced Consisting issues which arise with Soundtraxx Tsunami sound decoders on a Lenz DCC system.

The Soundtraxx Tsunami sound decoder is one of the few multifunction 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 locomotives in a consist to receive and respond to the brake command simultaneously.[1]

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 locomotive decoders support Advanced Consisting, but locomotive 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.

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

Lenz Consisting

How Lenz Handles Smart Consisting

There are five ways of creating an MU Consist:

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

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

For methods 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 a 2-digit consist address, or from the individual address of any locomotive 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 locomotive 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 locomotives.
  • When using the address of a locomotive in the consist ("m"), the function keys on the throttle control the functions for the selected locomotive only. To control functions for other locomotives in the consist, it is necessary to first select the individual locomotive address on the throttle.[2]
  • Because a locomotive 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 locomotive address is selected on the throttle. However, the Lenz system still sends function commands to the individual locomotive 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 locomotive no longer responds 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 locomotive number. As far as the Lenz system is concerned, it is simply controlling a normal locomotive with a 2-digit address.
  • Locomotive functions can be controlled by entering the individual locomotive address on the throttle but speed and direction cannot be controlled.
  • For decoders which support CV21 and CV22, locomotive functions can be controlled via the consist address and both locomotives will respond simultaneously to the same function button if 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 locomotive functions such as lights and horn, most people would be happy to have these functions apply to the lead locomotive only, in which case it makes sense to "drive" the consist by selecting the address of the lead locomotive 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 only allows the consist to be "driven" using the consist address, and locomotive functions cannot be controlled. This may be satisfactory for a non-sound locomotive, as the lights could potentially be turned on prior to moving the consist using the address of the lead locomotive, 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 locomotives 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 multifunction 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 locomotives simultaneously, by setting the throttle to the 2–digit consist address.
  • The behaviour of individual locomotives in response to function commands can be configured using CV21 and CV22,[3]. This can be used, for instance, to ensure that the headlight function only operates the headlight on the lead locomotive, not the headlights on the other locomotives in the consist.

There is a Gotcha!

If you set up an advanced consist by altering CV19 on the programming track, you will probably find that the locomotive'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) repeatedly sends out function commands to all locomotives 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 locomotive functions are restored to their intended state when the layout is first switched on or after an interruption to track power.[4]

The consequence of the refresh feature is that the Lenz system may be sending the same function command twice to the same locomotive, once via the consist address and once again via the individual locomotive address. For instance, if the headlight was off the last time the locomotive was driven via its individual 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 locomotives in the stack. The same applies to the horn function.

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

There is a Workaround

The workaround: Delete the individual locomotive 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 locomotive addresses are removed from the stack, the Lenz system will no longer send conflicting function commands to the locomotives in the consist and the functions can be controlled from the consist address.

Note that any attempt to drive a locomotive or activate any functions via its individual address will result in the locomotive address being added to the stack again. Somewhat surprisingly, selecting the individual address of a locomotive while in a consist to make a CV change via Operations Mode Programming 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 locomotive 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 locomotives 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 locomotive function mapping. This is because the rear light function for the consist needs to operate the front light on the rear-facing locomotive. This combination is not achievable by adjusting CV22 alone.

Function Swapping

There is a trick: The Tsunami Function Swapping feature (CV30 = 4), swaps 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 Lenz Smart Consisting if you need to be able to simultaneously control functions in multiple locomotives in the consist.
  2. To avoid Lenz Smart Consisting, configure the required locomotive CV's (e.g. CV19, CV21, CV22, etc.) on the programming track or on another layout.
  3. After confirming that the consist can be operated on the layout using the consist address, delete the individual locomotive address from the Lenz stack (if present).
  4. Avoid driving or operating functions using individual locomotive address while they are in a consist, or the address will be added back onto the stack. Use only the 2–digit consist address for the consist or operating functions.
  5. If you must activate a function on an individual locomotive, such as turning off an unwanted light, select its individual address on the throttle, activate the desired function, then after selecting another address on the throttle, remove the individual locomotive address from the stack.
  6. If necessary, adjust CV21 and CV22 to fine tune the operation of functions on individual locomotives in the consist. This can be done without adding the locomotive addresses back onto the stack.
  7. Have fun operating your consist.
  8. To remove one or all locomotives from a consist, select the individual locomotive address on the throttle and use Operatoins Mode programming to set CV19 to zero. The locomotive will now respond to its Extended or Primary Address rather than the consist address.

See Also

DCC Manuals

General Consisting Information

Other Tsunami Information

  1. The same braking feature is also available in the Soundtraxx MC1 and MC2 non-sound mobile decoders.
  2. The "–" button can scroll through the addresses for the locomotives in a consist as well as the overall consist address – see the LH100 manual for details.
  3. Provided the decoder supports these CVs
  4. 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.