Unit verification Module

The trip unit includes a validation module to check once after power-on the admissibility of the safety system settings read from the safety setting input unit and a verification module to check periodically the integrity and consistency of the safety system settings in RAM. 

The other possibility is to go in steps selecting only part of the functionality required to be implemented in software i.e. a partially digital RPS. For example, the trip unit may be selected for software implementation due to its simplicity. Although module simplicity, this software must be developed with an appropriate life-cycle using a structured methodology for real-time safety-critical system development, an adequate test life-cycle with an intensive verification and validation plan (see Section 5.3.2). 

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