Method for controlling data interchange between a vehicle diagnosis system and controllers arranged in vehicles, in which - an access request for at least one selected controller parameter that can be stored in a controller (131 - 133) of a vehicle is transmitted to a command interface of a communication control unit of the vehicle diagnosis system, wherein the access request is transmitted to the command interface by a function or a test program of the vehicle diagnosis system, wherein the vehicle diagnosis system comprises a flow control device for functions and/or test programs, wherein the access request comprises at least an indication of a control command and of a computer-based object - used by a function and/or by a test program - of the vehicle diagnosis system, wherein the computer-based object is associated with a controller parameter, wherein computer-based objects of the vehicle diagnosis system are organized into prescribable categories by means of data structure elements, and wherein vehicle-interface-specific and controller-specific access parameters associated with the computer-based objects or data structure elements are stored in a database, - access requests are converted into vehicle-interface-specific and controller-specific access parameters by the command interface, - at least one vehicle-interface-specific and controller-specific access parameter for accessing the selected controller parameter is used to ascertain at least a required communication resource of a vehicle interface and a required communication call via the vehicle interface, - the selected controller parameter is accessed by means of the ascertained communication resource and the ascertained communication call via the vehicle interface, wherein an acknowledgement from a controller of the vehicle to the vehicle diagnosis system is converted into at least one computer-based object of the vehicle diagnosis system by the command interface, - associations between computer-based objects and controller parameters are used by the command interface to ascertain a minimized number of communication calls required for controller parameter access. - an access request for at least one selected controller parameter that can be stored in a controller (131 - 133) of a vehicle is transmitted to a command interface of a communication control unit of the vehicle diagnosis system, wherein the access request is transmitted to the command interface by a function or a test program of the vehicle diagnosis system, wherein the vehicle diagnosis system comprises a flow control device for functions and/or test programs, wherein the access request comprises at least an indication of a control command and of a computer-based object - used by a function and/or by a test program - of the vehicle diagnosis system, wherein the computer-based object is associated with a controller parameter, wherein computer-based objects of the vehicle diagnosis system are organized into prescribable categories by means of data structure elements, and wherein vehicle-interface-specific and controller-specific access parameters associated with the computer-based objects or data structure elements are stored in a database, - access requests are converted into vehicle-interface-specific and controller-specific access parameters by the command interface, - at least one vehicle-interface-specific and controller-specific access parameter for accessing the selected controller parameter is used to ascertain at least a required communication resource of a vehicle interface and a required communication call via the vehicle interface, - the selected controller parameter is accessed by means of the ascertained communication resource and the ascertained communication call via the vehicle interface, wherein an acknowledgement from a controller of the vehicle to the vehicle diagnosis system is converted into at least one computer-based object of the vehicle diagnosis system by the command interface, - associations between computer-based objects and controller parameters are used by the command interface to ascertain a minimized number of communication calls required for controller parameter access.