Hi Pipo43

Using a decoder K84 to drive the Transfer Table 7294 (TT) is possible:
- one K84 SPDT (Single Pole Double Throw) is used in conjunction with 2 diodes in series so that the motor direction is selected from an AC voltage (16 VAC) and the DC motor in the TT
- a second K84 SPDT is used to briefly get the TT started (then it continues until the next track).
All this connects instead of the control panel delivered by Märklin.

Next you will have in Rocrail to declare a Turntable / Transfer table. The only difference is to tick the Transfer Table check box.
Next you need to provide Rocrail with Sensors:
- one sensor on the TT to tell Rocrail that a loco has arrived on it.
- one sensor for each track that is connected to the TT;
Next you need to fill the Track table indicating for each track:
- its number
- its decoder code (what code you send to the decoder to go to the track in question
- its TT sensor (the sensor indicating the TT is in front of the track.

This is the little I know. The missing link is what will convert the decoder code into orders for your K84.

I just found a TT decoder (Schiebebühne decoder) TT Decoder
Its cost is 50€ but I don't know if Rocrail can operate it (I will search)

Note: my layout has a TurnTable 7286 driven by a DigitalBahn DSD2010 decoder. I don't recall having seen that it may be used for transfer tables.

You may try writing an XML program to drive your TT
The program must
- keep at all times the present position of the TT (use a public variable)
- from the destination position, it must decide which direction the TT shall move
- stop the motor as soon as the destination track is reached.
Note: the 7294 TT has contacts to power up the center rail and the overhead on the track in front of the TT. This could be used to report the position of the TT and help your program to stop on the good track.
I hope this helps (not much though Sorry). I have made a search in the Rocrail German forum but I haven't found anything

Cheers
Jean