Patent ID: 7264090

Claim:
An elevator safety chain for monitoring the condition of a plurality of safety-related parameters of an elevator, said parameters including at least one of: hoistway door lock, car door lock, upper limits, lower limits, emergency stop switch, inspection switch, and overspeed sensor; characterized by: at least one transceiver ( 23 , 26 , 27 ) for transmitting interrogation signals and for receiving responses to said interrogation signals; and at least one passive radio frequency identification device ( 22 , 33 , 35 , 36 ) (RFID) associated with a corresponding one of said parameters, the frequency determining circuitry ( 40 , 41 , 43 , 44 , 47 , 48 ) of any said RFID being related to said corresponding parameter to have the capability to provide a transmitted response to an interrogation signal from one said transceiver indicative of a safe condition, when the condition of the corresponding parameter is safe, and not providing said indication of a safe condition when the condition of the corresponding parameter is not safe.