The present invention relates to secure paring of electronically controlled devices adapted to communicate with each other. Thus, a medical system is provided comprising a first unit and a second unit, the system comprising first means of communication allowing a first group of data types to be transmitted between the first unit and the second unit, and second means of communication allowing a second group of data types to be transmitted between the first unit and the second unit. In this way different properties of the two means of communication can be used to secure that certain data, e.g. during pairing of the two devices, can be transmitted in a more controlled way whereas other data can be transmitted in a less controlled way.