This thesis presents the modernization of an active pass box from Iskra PIO d.o.o. The pass box is used for transferring material from a non-clean to a clean room and vice versa. At the beginning, a detailed introduction to the topic is presented. After that, the clean room term is explained and the relevant standards along with procedures that lead to qualifying of the device are introduced. Further on, the basis for the implementation of the project is explained in detail, together with the appearance and usability of the device, the procedure for the entering and exporting of the material, the UV sterilization and the main display, as well as all alarms and warnings that the device can offer to the user. The PLC 1200 series and HMI KTP 400 Comfort from Siemens are used for the purpose of this thesis, of which pictures and technical descriptions are included. The thesis also describes the software and its handling, in our case, the TIA Portal of the Siemens manufacturer. A written program, air-flow control and controller settings, are presented at the end.