To provide Rocrail with events you must add some sensors to the turntable. On most turntable you can add without much affort those sensors: turntable_locdec_en In the worst case you can use reed schwitches in combination with magnets. But any how it is up to you to find the best solution for your turntable.
Needed for displaying and auto mode.
For generating the enter and in event.
The most common way ist to split up the bridge track into two equals occupancy sections, but its only at one rail necessary. (One side of the Bridge track). Alternatively, two Point sensors can be used near the ends of the Bridge track.
For the triggering and assignment of the events see: Turntable: Interface