challenge-and-response process for a safety system using a modified watchdog timer

摘要

Some embodiments of the present disclosure relate to a watchdog timer with an expanded functionality, which enable the watchdog timer, a process sequence of the microprocessor makes it possible to individually per object, which makes it possible to monitor that a single output signal is used, in order to determine whether in the case of a fault has occurred, watchdog timer. The watchdog timer has a state machine, which is mounted on the state variable during a watchdog period starting from an initial value is incremented. A received by a microprocessor controls the operation of the deterministic service request watchdog timer. The deterministic service request has an indicator for a monitoring process has to be carried out, a password and an estimated state variables on. A comparator determines on the basis of a comparison of the received password with an expected password and of the received estimated state variables with the actual state variables, whether the microprocessor operates properly.