Passive homing basic positioner S120

In my S120 drive I do passive homing of an axis, because the movement is continious but I could not find the exact modulus due to many chains between motor and final load.
In my trace of the actual position r2521 I see that the immediately after passive homing my position is not 0 but a small negative value althoug the home point is 0 (configured in the screen for active homing).
I have several axes like that that give the same negative position value after passive homing.
What could be the reason for this. I already changed P2603 to both values, but no influence.
Another thing I experienced with passive homing is that the precision is dependent on the speed activating the reference sensor, althoug it should be connected to a high speed digital input.
What is your experience to speed dependency of passive homing?