Tsunami setup for WiThrottle

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Summary: Configure a Tsunami decoder for easier use with a WiThrottle

WiThrottle in use with the Tsunami brake feature mapped to F5 function button.

This page concerns configuring a Soundtraxx Tsunami sound decoder for easier use with WiThrottle software.

For more information on the WiThrottle click the link or see the additional links at the bottom of this page.

Setting Up Your Tsunami to work with a WiThrottle

If using the simulated brake feature available with Tsunami sound decoders (as well as MC1 and MC2 non-sound decoders), it is obviously desirable to have ready access to the brake feature when driving a train.

By default, the Tsunami brake feature is mapped to function F11.

Some users remap the brake feature to F7 as it is then accessible on most DCC throttles without having to use a shift key or other means of accessing the higher-numbered functions. (This procedure and function mapping in detail is explained in detail in the Tsunami manuals.)

WiThrottle displays DCC functions F0-F5 on the main Throttle screen, and accessing additional functions (up to F28) requires scrolling the function buttons to the left to reveal the additional functions.

With standard Tsunami configuration, the brake feature can only be mapped within the range F7-F12. However, it is possible to remap the brake feature to lower number functions, such as F5, by using the Tsunami "function swapping" feature.

Function Swapping

Function swapping swaps the F5-F8 function group with the F9-12 function group. The idea is to allow higher-numbered functions to be remapped to low numbered functions to suit throttles which support a limited number of functions, or any other user requirement.

Enabling function swapping is simply a matter of setting CV30 to 4. (The default is zero.)

The CV's associated with function mapping are then switched around as well. The following table summarises the CV's which are altered:

Functions CV with no Function Swap CV with Function Swap
F5 CV43 CV39
F6 CV44 CV40
F7 CV45 CV41
F8 CV46 CV42
F9 CV39 CV43
F10 CV40 CV44
F11 CV41 CV45
F12 CV42 CV46

Function Swap for Tsunami Brake

Setting CV43 to 128 will map the brake feature to F5. If not used for another function, F7 should be unmapped as the default brake function by setting CV45 to zero. Note that the default of F11 for the brake became F7 due to the function swapping.

The common assignment for sound decoders of F8 for mute can be retained, by setting CV46 to 16. Again, the default mapping for the mute should be removed by setting CV42 to zero, otherwise the mute function would also be assigned to F12 (after function swapping).

Other functions can be similarly altered if desired, depending on what function are used in the particular loco. The important outcome is that the frequently-used functions for lights, horn/whistle and brake now all fall into the F0-F5 range and appear in the first group of function buttons in WiThrottle.

Function Swapping and Advanced Consisting

If using CV21 and CV22, which determine which functions for a particular loco can be controlled from the 2-digit consist address, the bits in CV21 and CV22 refer to the original "unswapped" functions. Refer to Consisting_with_Tsunami_decoders_and_Lenz#CV21_and_CV22_Configuration for more information.

WiThrottle Function Grouping

For reference, WiThrottle groups functions as follows:

Function "Pane" Function Range Number of Buttons
Default Pane F0 - F5 6
Pane 2 F6 - F13 8
Pane 3 F14 - F21 8
Pane 4 F22 - F28 7 (1 button position unused)

Engine shutdown for Diesel Tsunamis

A bonus for WiThrottle users with Diesel Tsunamis is that the STOP button on WiThrottle activates the engine shutdown sequence when the loco is stationary.

Typical CV values for Tsunami Braking

The following table summarises typical CV values to get realistic acceleration, coasting, and braking effects with Tsunami decoders with, of course, accompanying sound effects:

CV CV Description Typical Value (Steam Tsunami) Typical Value (Diesel Tsunami)
CV3 Acceleration 100 50
CV4 Decceleration 100 100
CV61 Brake Rate 200 200
(CV4 - CV61 + 128) Effective braking rate 28 28


  • The Tsunami calculates the effective braking rate automatically, based on the values of CV4 and CV61.
  • For programming purposes, the required setting of CV61 can be calculated based on the following formula:
CV61 = CV4 + 128 - desired effective braking rate
  • Obviously, the CV values can be adjusted to suit personal preferences. Increasing CV61 results in more severe braking. Whenever CV4 is adjusted, the effecting braking rate will be altered and CV61 may also have to be adjusted to compensate.
  • Setting CV61 to 0 (default) or 128 disables the braking effect.
  • Setting CV61 in the range 1 to 127 is not recommended as this results in a "negative" braking effect - the train takes longer to slow down with the brake applied than the normal decceleration rate.

See Also

Tsunami Information

WiThrottle Information