I found this description/logic in Generic CCOM (for A/C with old,non LCD FAP).
This logic is valid for "Solution 1", with cabin ready staus displayed in checklist. Also second, simplified option exist for CR shown as memo on rh side,called "Sloution 0", which only indicate CR button pressed by CC with gear downlocked. Hope this help...
CABIN READY SIGNALLING
The cabin crew can indicate the actual cabin status through pushing the Cabin Ready pushbutton.
This pushbutton is installed on the Miscellaneous Modul of the FAP near to the Water & Waste / EVAC function keys.
The Cabin Ready memo is reflected in the Take Off and Landing check lists and displayed on the
ECAM in the cockpit as follows:
‐ if the cabin is not ready :
CABIN..........CHECK
‐ if the cabin is ready :
CABIN..........READY
and the Cabin Ready pushbutton (LED) on the FAP illuminates.
SET THE CABIN READY INDICATION
Push the CABIN READY pushbutton on the FAP to set the respective indication, but depending
on the actual Flight Phase the Cabin Ready function is only available during :
‐ Take Off procedure after the first engine is started (oil pressure high), or
‐ Landing procedure when Flight Phases 6,7 or 8 are reached (altitude < 2 000 ft) and the slats
are extended.
RESET OF THE CABIN READY INDICATION
An automatic reset of the Cabin Ready indication is performed after take off, on the ground after
landing and also for go-around. In detail the following conditions must be fulfilled :
‐ during Take Off after Flight Phase 4 is reached (airspeed > 80 kt), or
‐ after landing when Flight Phase 9 (airspeed < 80 kt) +30 s is reached, or
‐ during Go Around with slats retracted in Flight Phase 5, 6 or 7, or
‐ after Touch And Go with slats retracted in Flight Phase 4, 5, 6, 7, or 8, or
‐ when the Cabin Ready pushbutton on the FAP is pushed a second time.