A method for operating a machine control system and a corresponding machine control system uses a portable hand-held terminal for functionally influencing at least one machine controller. The terminal includes at least one emergency stop actuation element for terminating potentially dangerous machine operations. The controller and/or the terminal is adapted for indicating a representation of the control system on the terminal display. The controller and/or the hand-held terminal is adapted for indicating the operational range(s) of the at least one emergency stop actuation element by the terminal display. The controller and/or the hand-held terminal are further adapted for simultaneously representing the operational range(s) of the at least one emergency stop actuation element by selective, fail-safe controlling of at least one lighting device at the hand-held terminal and/or at least one discrete lighting device in or at the at least one emergency stop actuation element at the hand-held terminal.