The present invention relates to secure paring of electronically controlled devices configured to communicate with each other. A medical system is provided comprising a first unit and a second unit, the system comprising a first communication link allowing a first group of data types to be transmitted between the first unit and the second unit, and a second communication link allowing a second group of data types to be transmitted between the first unit and the second unit. Different properties of the communication links may be used to ensure 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.