Causes a health hazard in the event of damage to property or the environment can be very diverse, as well as technical measures to prevent their occurrence or mitigate their consequences, therefore it is necessary to distinguish between different types of security.
Due to the complexity of security problems in the industry has introduced IEC 61508 is relatively new term so-called: functional safety, which must respond to the inputs of the system, including the likely operator error, hardware or software failure, and environmental changes.
In connection with the development of industrial automation, functional safety particularly important for so called: safety related parts of control systems, i.e. for all parts of the control circuits, which ensure execution of security functions and whose term failure could cause a hazardous situation with a high level of risk.