Method for functionally safe connection identification for a bilateral data interchange of safety-oriented data (F B -Data, F A -Data) between two communication subscribers (A, B) in a communication system, wherein - safety-oriented data are interchanged by means of safety-oriented communication, - address relationships that comprise destination addresses and source addresses are firmly planned for the safety-oriented communication, - a first data consumer (CI A) having a first address identifier (ID_CI A) and a first data provider (PI A) having a second address identifier (ID_PI A) are operated in a first communication subscriber, - a second data provider (PG B) having a third address identifier (ID_PG B) is operated, and additionally a second data consumer (CG B) is operated, in a second communication subscriber, and - a first unidirectional connection is set up between the first data consumer (CI A) and the second data provider (PG B), and - a second unidirectional connection is set up between the first data provider (PI A) and the second data consumer (CG B), characterized in that - the first communication subscriber ascertains the third address identifier (ID_PG B), the third address identifier (ID_PG B) being ascertained via a side channel that is independent of the communication system or on the basis of a configuration database using position data (x, y, z) of the first communication subscriber, - an identifier is produced in the first communication subscriber using a computation rule (f) that is applied to a unique value, and this identifier is communicated to the first data consumer (CI A), - the first data consumer (CI A) transmits the unique value to the second data provider (PG B) in a first request message, - the second data provider (PG B) responds to the first data consumer with a first response message containing first safety-oriented data (F B -Data) and the third address identifier (ID_PG B), - a check being performed in the first data consumer (CI A) to determine whether the first response message contains the third address identifier (ID_PG B), and, if the result of this check is positive, the first safety-oriented data (F B -Data) are accepted, and if the result of this check is negative, the first safety-oriented data are rejected, the first unidirectional connection being functionally protected by means of the third address identifier (ID_PG B), - the computation rule (f) is used to likewise produce the identifier in the second communication subscriber, - and the identifier is used to functionally protect the second unidirectional connection between the first data provider (PI A) and the second data consumer (CG B). - safety-oriented data are interchanged by means of safety-oriented communication, - address relationships that comprise destination addresses and source addresses are firmly planned for the safety-oriented communication, - a first data consumer (CI A) having a first address identifier (ID_CI A) and a first data provider (PI A) having a second address identifier (ID_PI A) are operated in a first communication subscriber, - a second data provider (PG B) having a third address identifier (ID_PG B) is operated, and additionally a second data consumer (CG B) is operated, in a second communication subscriber, and - a first unidirectional connection is set up between the first data consumer (CI A) and the second data provider (PG B), and - a second unidirectional connection is set up between the first data provider (PI A) and the second data consumer (CG B), - the first communication subscriber ascertains the third address identifier (ID_PG B), the third address identifier (ID_PG B) being ascertained via a side channel that is independent of the communication system or on the basis of a configuration database using position data (x, y, z) of the first communication subscriber, - an identifier is produced in the first communication subscriber using a computation rule (f) that is applied to a unique value, and this identifier is communicated to the first data consumer (CI A), - the first data consumer (CI A) transmits the unique value to the second data provider (PG B) in a first request message, - the second data provider (PG B) responds to the first data consumer with a first response message containing first safety-oriented data (F B -Data) and the third address identifier (ID_PG B), - a check being performed in the first data consumer (CI A) to determine whether the first response message contains the third address identifier (ID_PG B), and, if the result of this check is positive, the first safety-oriented data (F B -Data) are accepted, and if the result of this check is negative, the first safety-oriented data are rejected, the first unidirectional connection being functionally protected by means of the third address identifier (ID_PG B), - the computation rule (f) is used to likewise produce the identifier in the second communication subscriber, - and the identifier is used to functionally protect the second unidirectional connection between the first data provider (PI A) and the second data consumer (CG B).