Abstract: The invention relates to a robot arm comprising a plurality of robot joints mechanically connecting a robot base to a robot tool flange wherein a robot controller is configured for controlling movement of said plurality of robot joints and thereby movement of said robot tool flange. The robot controller is connected to an interface device comprising an input device via which a user is able to communicate with said robot controller and thereby change mode of operation of the robot arm. The input device is a mechanical multifunctional input device and in response to a first predetermined sequence of activation applied to the input device, the robot controller is arranged to change mode of operation to a stop mode, and in response to a second predetermined sequence of activation applied to the input device, the robot controller is arranged to change mode of operation to a second mode of operation.