Ratio counter — solution of the relation between safety and availability of a communication system

Safety and reliability belong to the main quality attributes of a safety relevant control system. If a communication system is a component of a safety relevant control system then because of its properties it can also significantly affect the safety and reliability of the entire safety relevant control system. Safety and reliability attributes of a communication system can be influenced by a proper application of a so-called ratio criterion. Although the ratio criterion is often being utilised in practical applications, the parameters of ratio criterion are usually set intuitively. The contribution is focused on the problem of ratio counter parameters choice, which in co-operation with the safety code decoder provides operational checking of a non-trusted transmission system.