Abstract The COMPASS tokamak has started its operation recently at the Institute of Plasma Physics AS CR in Prague, Czech Republic. An important issue of the operation is the interlock system, which secures the safety of the personnel. The personnel protection is based on a restricted access into the experimental hall during the tokamak operation. An experimental hall access system, based on Honeywell WIN-PAK™2005, allows to set the status of the experimental area and to control the movement of the personnel. A hardware interlock, based on a PLC MicroPEL M66, interprets the experimental hall status and controls the safety of the operation of key systems accordingly. The permit for operation is granted and the real status of the systems is reported by hard-wired potential-less contacts. The PLC provides a HW interface between Actuators (relays and switches) and it is connected on PESNET bus. Second site of personnel protection system is created on a PC where runs a .NET application on MS Windows XP. This PC is connected with PLC via PESNET bus (on RS485 layer) and it creates an operator interface. Details of the set-up are described in this contribution.