Patent ID: 8464841

Claim:
A method for determining a movement and/or a position of an elevator car of an elevator system with a first monitoring unit for analyzing first signals of a first sensor device to obtain information about the movement and/or the position of the elevator car, and to detect any occurrence of faulty behavior of the elevator system, and to initiate corresponding safety measures, and with a second sensor device, which does not operate on the principle of the first sensor device, for registering a change of the movement state of the elevator car and emitting corresponding second signals to a second monitoring unit, which second monitoring unit analyzes the second signals and detects an occurrence of a change of the movement state of the elevator car, comprising the steps of: a. determining an instant of a change in the movement state of the elevator car with the second monitoring unit; b. monitoring the occurrence of at least one of a first movement signal or a function signal generated by the first monitoring unit within at least one time-window that follows the instant of change; and c. generating a first fault signal should the first movement signal or the function signal, which indicates coherent functioning of the first monitoring unit, not occur within the time-window.