A method for operating a door operator, includes inserting a first functional module into a slot of the door operator. The first functional module includes first information data function to be enabled. The first information data is transmitted to the door operator and, determining which additional functions are to be enabled. A first unique first identification is generated in the door operator. This generated first identification is transmitted back to the first functional module and saved in the first functional module. The determined functions to be enabled are activated, respectively enabled in the door operator.