Device for coupling a first bus system with a second bus system for bidirectional communication between the first bus system and the second bus system, comprising - a data transmission device for transmission of forward-directed data from the first bus system to the second bus system and for transmitting backward-directed data from the second bus system to the first bus system, - a data manipulation device for the manipulation of forward-directed data and/or backward-directed data, and characterized by - an instruction memory for storing manipulation instructions which allow the manipulation of data by the data manipulation device, wherein the manipulation instructions are reloadable into the instruction memory, - a processor for performing common tasks of a bus coupler and in addition - an instruction execution device for executing the manipulation instructions and generation of manipulation data, - a manipulation data buffer for the intermediate storage of generated manipulation data for the data manipulation device, wherein the manipulation instructions are modularly reloadable into the instruction memory, are reloadable by the user, are changeable by the user, are actualisable by an update mechanism, are subsequently replaceable and/or are designed as reloadable functions, - wherein the manipulation instructions refer to forward-directed and/or backward-directed data and wherein the instruction execution device is set up to access forward-directed and/or backward-directed data in order to execute the manipulation instructions relating to this data, - wherein said data manipulation device is adapted to link the manipulation data intermediately stored in the manipulation data buffer with the forward-directed data and/or backward-directed data. - a data transmission device for transmission of forward-directed data from the first bus system to the second bus system and for transmitting backward-directed data from the second bus system to the first bus system, - a data manipulation device for the manipulation of forward-directed data and/or backward-directed data, - a data manipulation device for the manipulation of forward-directed data and/or backward-directed data, - an instruction memory for storing manipulation instructions which allow the manipulation of data by the data manipulation device, wherein the manipulation instructions are reloadable into the instruction memory, - a processor for performing common tasks of a bus coupler and in addition - an instruction execution device for executing the manipulation instructions and generation of manipulation data, - a manipulation data buffer for the intermediate storage of generated manipulation data for the data manipulation device, - wherein the manipulation instructions refer to forward-directed and/or backward-directed data and wherein the instruction execution device is set up to access forward-directed and/or backward-directed data in order to execute the manipulation instructions relating to this data, - wherein said data manipulation device is adapted to link the manipulation data intermediately stored in the manipulation data buffer with the forward-directed data and/or backward-directed data.