Method for Functionally Secure Connection Identification

A method for functionally secure connection identification during a data exchange between two communication subscribers in a communication system, a first communication subscriber operating as a data provider with a first address identifier and a second communication subscriber operating as a data requester with a second address identifier, the method comprising:

• sending, by the second communication subscriber, an order number of the data request and its second address identifier to the first communication subscriber, via a request of safety-related data of the first communication subscriber in a request message;
• responding, by the first communication subscriber with a response message comprising the safety-related data, the first address identifier, the order number and the second address identifier;
• determining, after receipt of the response message in the second communication subscriber, whether said message contains the second address identifier of the requesting second communication subscriber, whether this message contains the order number of the request message of the second communication subscriber and whether this message comprises the first address identifier of the requested first communication subscriber;
• and
• accepting the safety-related data in an event that all checks are positive, otherwise discarding the safety-related data when any of the checks is not positive.