An operating unit for operating a module, which is designed in particular as a device in an automation system and has a module-side communication interface, comprising - fastening means (181, 182) for detachably fastening the operating unit to the module, wherein the fastening means (181, 182) are designed for fastening the operating unit onto modules of different types of modules, - input and output means (140, 142) for input and output of information, - a first communication interface, which is connected to the module-side communication interface when the operating unit is fastened and is designed for data exchange between the operating unit and the module, wherein the operating unit is designed to receive and store identification information which identifies a type of module from a module connected to the first communication interface, - a microcontroller which can program itself during run time, - at least one memory (152, 154, 162, 164) for storing an operating application with a first and a second application part, wherein the memory comprises a first memory area in which the first application part is stored and a second memory area for storing the second application part, wherein accesses between the application parts are carried out via a predefined interface, and wherein the operating unit is designed to load the second application part from a connected module and store it in the second memory area, wherein the operating unit is designed to receive the identification information from the connected module before downloading and storing the second application part and to compare this information with the identification information stored last and to load the second application part from the connected module and save the received identification information only if the received identification information and the identification information stored last are different, - a second communication interface for communication with a separate operating device. - fastening means (181, 182) for detachably fastening the operating unit to the module, wherein the fastening means (181, 182) are designed for fastening the operating unit onto modules of different types of modules, - input and output means (140, 142) for input and output of information, - a first communication interface, which is connected to the module-side communication interface when the operating unit is fastened and is designed for data exchange between the operating unit and the module, wherein the operating unit is designed to receive and store identification information which identifies a type of module from a module connected to the first communication interface, - a microcontroller which can program itself during run time, - at least one memory (152, 154, 162, 164) for storing an operating application with a first and a second application part, wherein the memory comprises a first memory area in which the first application part is stored and a second memory area for storing the second application part, wherein accesses between the application parts are carried out via a predefined interface, and wherein the operating unit is designed to load the second application part from a connected module and store it in the second memory area, wherein the operating unit is designed to receive the identification information from the connected module before downloading and storing the second application part and to compare this information with the identification information stored last and to load the second application part from the connected module and save the received identification information only if the received identification information and the identification information stored last are different, - a second communication interface for communication with a separate operating device.