Elevator safety system, elevator system and method of operating an elevator system

Elevator safety system comprising:

• a plurality of door safety units (12), each door safety unit (12) assigned to an elevator hoistway door (10) and configured for monitoring a condition of the assigned elevator hoistway door (10);
• a communication bus (16) connecting the plurality of door safety units (12);
• a control unit (13) connected to the communication bus (16) for allowing communication between the plurality of door safety units (12) and the control unit (13);
• and
• at least one position sensor (19) configured for providing information about the current position of an elevator car (6) within a hoistway (4);
• wherein the control unit (13) is configured
• for polling door safety units (12) included in a subset (S1, S2) of the door safety units (12) which are located within a predetermined distance (D1, D2) from the current position of the elevator car (6);
• and
• for polling door safety units (12) which are not included in said subset (S1, S2) less frequently or not at all.