An apparatus for storing control units comprises a cabinet (10) with a plurality of rails (41) arranged horizontally along inner sidewalls and is configured to receive a plurality of drawers (40) above each other. Each drawer (40) comprises a plurality of docking sockets (1), each docking socket (1) being configured to receive and retain one control unit. The apparatus comprises a robotic elevator device (20) adapted to move an elevator table (30) in a vertical direction to a vertical position corresponding to a pair of rails (41) into which a drawer (40) is to be inserted or from which the drawer (40) is to be withdrawn. The elevator table (30) comprises a linear motor (32, 34) capable of moving the drawer (40) along a pair of rails (41) in a longitudinal direction. A robotic gripper, which may be internal or external to the apparatus, is capable of putting control units into the docking sockets or withdrawing the control units from the docking sockets.