LocoDialog Interface Tab.

Interface ID

Only set this to the IID you set in the rocrail.ini if your setup has more than one CS connected.


See: Addressing


The decoder address which range depends on the decoder type and underlying Command Station.

  • Marklin mfx-Decoders may need special settings depending on the command station. See the wiki page of the relevant command station, if applicable.
  • Locos with address 0 (zero) are considered to be analog locos without decoders which are only supported by TrackDriver systems. “Stretched 0 Bit” according to NEM 670 is not supported.

The optional second address can be used for T4T1).


Some command stations do support multiple protocols; Check the user manual for details.
If the address is set to zero the protocol should be set to Analog for Track Driver support.

Protocol version

If the Command Station cannot determine the decoder type itself you must specify the version as listed here ddx-en or found in the SRCP description. Most systems do not use this parameter because it is set directly in the CS or it does only support one version.

Number of functions

Number of extra functions supported by the decoder used.

Decoder steps

Number of speed steps the decoder is set up to. Rocrail needs the number of the decoder's speed steps e. g. to be able to calculate the wanted velocity in percent or KM/H.

  • The number of speed steps of the decoder, the command station and in Rocrail must match otherwise the loco light (F0) may not work correctly.

The optional second speed steps can be used for T4T2).


The KMH column, the second one, is for displaying the throttle speed in kmh and is available only when Percent mode is selected

  • All KMH and V values must be set greater then zero to activate the display values
  • Percent values in between will be interpolated.
  • This KMH values will be handled with KMH settings in objects, e.g. max kmh values in blocks, routes, cars and trains (11.056+)


With the check-box Percent activated velocities are in percent of the maximum decoder step. With a decoder offering 28 decoder steps as an example, 100% equals decoder step 28 whereas 50% equals decoder step 14.

Note: V_Max reduces the maximum velocity of the locomotive in percent-mode if values below 100 (percent) are entered.
Note: It is generally not recommended to reduce a locomotive's maximum speed by only V_Max as the number of available decoder steps would be reduced. Example: A locomotive equipped with a Motorola decoder featuring 14 decoder steps has a maximum velocity of 200 km/h but the maximum velocity of the original engine is 120 km/h. Reducing V_max to 60%, which is decoder step eight, leaves eight speed steps for the 120 km/h range. This will lead to an increase / decrease of 15 km/h (120 km/h : 8) per decoder step. It is thus favourable to adjust the decoder itself to the desired maximum speed if possible leaving V_Max to values around 100%. Decoders without any internal speed setting, however, may be adjusted by decreasing V_Max if necessary.


Unchecking the check-box Percent activates the km/h mode.

Note: The locomotives maximum velocity is not influenced by V_Max in km/h mode.

V_Max has to be set to the velocity the model engine gains at the highest decoder step. This value is the basis for Rocrail's calculation of all other velocities. Example: If a model engine was adjusted to 80 km/h maximum speed 80 has to be entered into the field V_max. If, for example, 35 km/h is the desired speed for V_Mid 35 has to be entered there.

Note: A linear speed curve is a prerequisite for a working km/h mode, e.g. a V_Mid of 35 indeed yields 35 km/h. If this condition can not be fulfilled it is recommended to use percent mode instead.

V_min - KMH_min / V_Rmin¹

This should be set to the slowest reasonable locomotive velocity and is set when running in auto mode on the pre2in event (see also Sensors and Blocks).
The value is in km/h or % depending on V_mode (see below).

V_Rmin: This should be set to the slowest possible reverse locomotive velocity. V_min will be used if left to zero.

V_mid - KMH_mid / V_Rmid¹

This should be set to a medium locomotive velocity and is set when running in auto mode on the enter event.
The value is in km/h or % depending on V_mode (see below).

V_Rmid: This should be set to a medium reverse locomotive velocity. V_mid will be used if left to zero.

V_cru - KMH_cru / V_Rcru¹

If set greater then zero this is used as the cruise locomotive velocity instead of 80% of V_max
The value is in km/h or % depending on V_mode (see below).

V_Rcru: This should be set to the cruise reverse locomotive velocity. V_cru will be used if left to zero.

V_max - KMH_max / V_Rmax¹

V_max has two different meanings depending on V_mode (see below):

  1. In percent mode the value defines the maximum velocity in percent of the maximum number of decoder steps
  2. In km/h mode the value has to represent the velocity of the loco at highest decoder step (i. e. 28/128, or 14,27 depending on the decoder).
    The value is not used to adjust the maximum velocity. This has to be achieved by adjusting the decoder itself (e. g. CV6 for DCC compatible decoders).

V_max sec.

The optional second V_max can be used for T4T3).

V_Rmax: Should be set accordingly for reverse running. V_max will be used if left to zero.

¹) Reverse velocity settings are for automatic mode only and do not apply to throttles or other manual controllers.



Only to be used when this is an analog loco in combination of the Dinamo CS. (Check the documentation.)
A value of 5 is a good start to experiment with.

Poll info

Some bus systems, like XpressNet, do not propagate loco changes issued by throttles.
By activating this option, and if the loco is not in auto mode, every second a request is send to the Command Station to get the actual information needed to update the Rocrail clients.


When the loco runs the wrong direction this flag can be swapped.
For commuters this flag is automatically swapped in terminal station block types and for routes in the opposite direction.


Default means the loco run direction when coming out of the box; some older decoders do only remember the direction for a short period after shut-down the power.
When the decoder has “forgotten” its previous direction, then it will run the next time in its “default” direction.


If default is not set the placing type is swapped.

Read also: Direction in Rocrail

Dir pause

Some old Delta like decoders need some pause between a direction change and the last turnout command. With about 100ms this will do the trick when running DDX.


Adjust acceleration

  • Only available in combination with DCC and Trains.
  • The max. load and the acceleration range must be set greater then zero.
  • If the total train weight is zero the min. acceleration value is used.
  • The new calculated acceleration value will be written by POM in CV3 after assigning a train or in case Car properties have been modified.
  • The min. acceleration value will be written by POM in CV3 after releasing the assigned train.

Max. Load

The max. load for this locomotive in tons.

Min./Max. Acceleration

The CV3 range to use for loads between zero and max. load.

Server trace example

20130723.090557.995 r9999I cmdrD000 OLoc     2707 processing cmd="assigntrain" for [E03]
20130723.090557.995 r9999I cmdrD000 OLoc     2848 consist [train1] assigned to loco [E03]
20130723.090557.995 r9999I cmdrD000 OCar     0354 car [test] loaded weight [500]
20130723.090557.995 r9999I cmdrD000 OLoc     2026 loco [E03] adjust acceleration: CV3=16
20130723.090557.995 r9999I cmdrD000 OVirtual 0437 program cmd=1 mode=0
20130723.090557.995 r9999I cmdrD000 OVirtual 0465 POM: set CV3 of loc 1003 to 16...
20130723.090557.995 r9999I cmdrD000 OLoc     2079 loco [E03] train length=56 weight=500 
1) , 2) , 3) TCCS (TrainCoupling&CommunicationSystem)

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