Method for operating a control system for a technical plant, in particular a manufacturing or process plant, which has at least one operator station server and one operator station client, wherein a data model is implemented on the operator station server, wherein the data model features a linkage of different data which is combined in a common model, and wherein the operator station client has a display unit and a control unit, comprising a) Transmission of visualisation information representing the data model to the display unit of the operator station client by the operator station server, b) Generation by the display unit of the operator station client of a graphical presentation of the received visualisation information for an operator of the control system, c) Receiving of operator commands to change the graphical presentation in the display unit, and forwarding of these commands to the control unit by the display unit, d) Receiving of the commands from the display unit by the control unit e) Generation of revised visualisation information from the received commands and direct transmission of the revised visualisation information to the display unit by the control unit in order to adjust the graphical presentation of the display unit, f) Generation of adjustment commands from the received commands and transmission thereof directly to the data model on the operator station server by the control unit so that the operator station server adjusts the data model in response to the operator's commands, g) Generation of a checksum specific to the current graphical presentation by the display unit after the display unit has received the revised visualisation information from the control unit and has then adjusted the graphical presentation accordingly, h) Generation of a checksum specific to the current data model by the operator station server after the operator station server has received the adjustment commands from the control unit and has then adjusted the data model accordingly, i) Transferring of the checksum from the operator station server to the display unit, j) Comparing of the checksum generated by the display unit with the checksum generated by the operator station server in order to be able to detect any inconsistency between the graphical presentation of the display unit and the data model on the operator station server, k) In the event of inconsistency between the two compared checksums, requesting of visualisation information representing the current data model from the operator station server by the display unit, l) Transferring of the visualisation information representing the current data model from the operator station server to the display unit and graphical presentation of the visualisation information. a) Transmission of visualisation information representing the data model to the display unit of the operator station client by the operator station server, b) Generation by the display unit of the operator station client of a graphical presentation of the received visualisation information for an operator of the control system, c) Receiving of operator commands to change the graphical presentation in the display unit, and forwarding of these commands to the control unit by the display unit, d) Receiving of the commands from the display unit by the control unit e) Generation of revised visualisation information from the received commands and direct transmission of the revised visualisation information to the display unit by the control unit in order to adjust the graphical presentation of the display unit, f) Generation of adjustment commands from the received commands and transmission thereof directly to the data model on the operator station server by the control unit so that the operator station server adjusts the data model in response to the operator's commands, g) Generation of a checksum specific to the current graphical presentation by the display unit after the display unit has received the revised visualisation information from the control unit and has then adjusted the graphical presentation accordingly, h) Generation of a checksum specific to the current data model by the operator station server after the operator station server has received the adjustment commands from the control unit and has then adjusted the data model accordingly, i) Transferring of the checksum from the operator station server to the display unit, j) Comparing of the checksum generated by the display unit with the checksum generated by the operator station server in order to be able to detect any inconsistency between the graphical presentation of the display unit and the data model on the operator station server, k) In the event of inconsistency between the two compared checksums, requesting of visualisation information representing the current data model from the operator station server by the display unit, l) Transferring of the visualisation information representing the current data model from the operator station server to the display unit and graphical presentation of the visualisation information.