Method for modifying a program of an industrial automation component, wherein the program consists of a plurality of program elements (A,..., H), wherein the program is modified by transferring modified program elements (A,..., H) and program elements (A,..., H) that are dependent thereon from an engineering system to the automation component, wherein at least part of the program is structured in units (U_D, U_P), wherein a unit comprises a group of program elements (A,..., H), wherein a unit (U_D, U_P) can comprise both published program elements (PE; A, B, E, F) each having an interface referenced by the program elements of other units (U_D, U_P) and unpublished program elements (NPE; C, D, G, H) each having an interface referenced only within the same unit, characterized in that characteristics of the interfaces of the published program elements (PE; A, B, E, F) of each unit (U_D, U_P) are used to form a checksum (UIFFP) and to associate said checksum with the unit (U_D, U_P) in each case, in that a modification to at least one program element (A,..., H) of the version of a unit (U_D, U_P) that is stored on the engineering system results in the checksum (UIFFP) of the thus modified unit (U_D, U_P) being compared with the checksum (UIFFP) of the previous version of this unit (U_D, U_P) that is present on the automation component, and in that, in the event of the checksums (UIFFP) matching, only the modified unit (U_D, U_P) is transferred from the engineering system to the automation component, and otherwise all other units (U_D, U_P) that reference the modified unit (U_D, U_P) are also transferred to the automation component in their respective current version of the engineering system. wherein the program consists of a plurality of program elements (A,..., H), wherein the program is modified by transferring modified program elements (A,..., H) and program elements (A,..., H) that are dependent thereon from an engineering system to the automation component, wherein at least part of the program is structured in units (U_D, U_P), wherein a unit comprises a group of program elements (A,..., H), wherein a unit (U_D, U_P) can comprise both published program elements (PE; A, B, E, F) each having an interface referenced by the program elements of other units (U_D, U_P) and unpublished program elements (NPE; C, D, G, H) each having an interface referenced only within the same unit, characterized in that characteristics of the interfaces of the published program elements (PE; A, B, E, F) of each unit (U_D, U_P) are used to form a checksum (UIFFP) and to associate said checksum with the unit (U_D, U_P) in each case, in that a modification to at least one program element (A,..., H) of the version of a unit (U_D, U_P) that is stored on the engineering system results in the checksum (UIFFP) of the thus modified unit (U_D, U_P) being compared with the checksum (UIFFP) of the previous version of this unit (U_D, U_P) that is present on the automation component, and in that, in the event of the checksums (UIFFP) matching, only the modified unit (U_D, U_P) is transferred from the engineering system to the automation component, and otherwise all other units (U_D, U_P) that reference the modified unit (U_D, U_P) are also transferred to the automation component in their respective current version of the engineering system.