Patent ID: 7237653

Claim:
An elevator controller, comprising: at least two control systems, each control system having an arithmetic operation processing unit; and a common memory, data of which can be mutually read out and written between the arithmetic operation processing units of the control systems, wherein the arithmetic operation processing unit of each of the control systems, when taking in a pulse train signal used for elevator control as an input signal, takes in both a pulse train signal detected with detection means of one's own system and a pulse train signal detected with detection means of another system as input signals, when a difference between counting results of the number of pulses of the input signal in both of the systems falls within a predetermined input signal allowable error range, executes arithmetic operation processing required for the elevator control using the input signal from the detection means of a predetermined control system and writes arithmetic operation results to the common memory and reads out the arithmetic operation results of another system from the common memory to obtain a difference between the arithmetic operation results in one's own system and the arithmetic operation results in the other system, when the difference between those arithmetic operation results falls within a predetermined arithmetic operation result allowable error range, judges that all of the control systems are in a normal state and issues a control operation permission command for permitting a control operation for the elevator, and when the difference between the input signals is beyond the input signal allowable error range, or when the difference between the arithmetic operation results is beyond the arithmetic operation result allowable error range, the arithmetic operation processing unit of each of the control systems judges that one of the control systems is in an abnormal state and issues a control operation stop command for stopping the control operation for the elevator.