Patent ID: 8292038

Claim:
A device for controlling movement of a plurality of elevator cars in a single hoistway, comprising: a single safety chain including a plurality of communication modules each situated to determine when a respective hoistway door is open; a single door monitor module that receives at least one indication from at least one of the communication modules that determines that its respective hoistway door is open; and a relay module including a first relay for controlling whether a first elevator car can move in the hoistway and a second relay for controlling whether a second elevator car can move in the hoistway, the door monitor module controlling an operative condition of the first and second relays; wherein the door monitor module is configured to determine a position of each of the plurality of elevator cars; determine a condition of each of a plurality of doors along the hoistway based on indications from the single safety chain; determine when at least one of the doors along the hoistway is open based on the at least one indication from the at least one of the communication modules; and place the first relay in a selected operative state to prevent movement of the first elevator car if the first elevator car is stopped at a landing corresponding to the at least one open door, or place the second relay in a selected operative state to prevent movement of the second elevator car if the second elevator car is stopped at a landing corresponding to the at least one open door, or place the first and second relays into the selected operative state if neither of the first or second elevator car is stopped at a landing corresponding to the at least one open door.