Abstract: The invention relates to a method and device for improving the reliability of a computer system by using a CompactPCI bus. The computer system comprises a bus (PCI), an interface circuit (1) and a plug-in unit (2) which is connected to the bus via the interface circuit (1). In the method, the interface circuit (1) is provided with a watchdog timer (3), which is started upon the start of addressing of the plug-in unit, and addressing is terminated if its duration exceeds a time value preset in the watchdog timer (3). The interface circuit (1) of the invention comprises a watchdog timer (3), means (4) for starting timing upon the start of addressing, and means (5) for terminating the addressing if its duration exceeds the time value preset in the watchdog timer (3).