Functional safety means the part of the security of a system that depends on the correct functioning of the safety related ( sub) systems and external risk reduction facilities. Not for functional safety include electrical safety, fire safety, radiation protection. Because security can be achieved by simply adding if necessary set the intended function and a secure state is assumed, one also speaks of the security integrity of the system.
With the complexity of electronic, especially of programmable systems and the diversity of possibilities of error increases. According to the standard IEC 61508 calls " Functional safety of electrical / electronic / programmable electronic systems," the application of various methods for the control of faults:
- Avoid systematic errors in the development, eg Specification and implementation errors
- Monitoring during operation to detect random errors
- Secure control of detected errors and transition to a pre- defined safe state.
Causes of random errors can be aging or physical phenomena ( soft errors ).
Operating errors are not covered by the standards, as the system then an evaluation of manual intervention ( " intentional misuse by the operator to avoid an even greater harm" or " operator error " ) would have to meet. An adaptation of this series of standards for motor vehicles is the ISO 26262 standard.