The present invention relates to a control system for controlling operation of a numerically controlled machine tool (100), the system comprising a back-end control device (300) and a front-end control device (200) communicably connected to the back-end control device (300). The back-end control device (300) comprises a numerical controller (310), a programmable logic controller (320), a first communication interface (330) being communicably connected to the numerical controller (310) and the programmable logic controller (320), and an interface server module (410) of a second communication interface (400) being communicably connected to the first communication interface (330). The front-end control device (200) comprises an interface client module (420a) of the second communication interface (400) being adapted to communicably connect to the interface server module (410), second processing means (210) for executing a second operating system (213), a basic module application (211), and a plurality of control applications (212a-212g), the basic module application (211) being for accessing data in the numerical controller (310) and the programmable logic controller (320) via the one or more interface client modules (420a), the interface server module (410) and the first communication interface (330), a display unit (230) for displaying one or more control screens to a user, an input unit (240) for receiving control input operations from the user, and a first human-machine interface (250) being communicably connected to the display unit (230) and the input unit (240), and including a first graphical user interface (251) for controlling the one or more control screens displayed on the display unit (230) and for processing control input operations of the user.