Intensive rehabilitation training of the arm can improve motor recovery in patients with neurological impairment. Actuated robots are becoming more and more common in this field as they serve to actively assist, enhance and assess neurorehabilitation. However, there is currently no actuated robot available specifically designed for the rehabilitation of children with upper extremity motor impairments. In this paper, we describe a completely new designed exoskeleton-based arm robot, ChARMin, with four degrees of freedom to guide and assist shoulder and elbow movements for young patients with motor impairments. The serial mechanical structure includes parallel kinematics for remote center of rotation actuation. This allows to keep a safe distance between parts of the robot and the patient and it reduces friction, while being highly adaptable to cover the anthropometrics for patients aged 5 to 18 years. Additionally, a novel passive weight support mechanism and 6 degrees of freedom force sensors are installed for a safe and transparent operation of the device.