Abstract: A method and system is provided for a nuclear reactor safety related application. The method includes executing two forms of a same application-specific logic, one of the two forms implemented as hardware logic, and the other of the two forms implemented as software instructions for execution by microprocessor-based controlling software. Each form of the application-specific logic is executed with a same set of inputs. The method compares a result produced from the execution of the hardware-implemented form to a result produced from the execution of the software-implemented form. When the compared results concur, the controlling software performs actions associated with the concurring results by executing microprocessor-based software. When the compared results fail to concur, the controlling software reports the failure of the compared results to concur to an operator by executing microprocessor-based software, and thereafter places the microprocessor-based software system into an inoperative (INOP) mode.

Abstract: A safety instrument suitable for use in an industrial application includes a logic card having a microcontroller configured to perform self-test of the instrument and surveillance functions of an external system that is monitored and/or controlled by the instrument. The logic card also includes at least one complex programmable logic device (CPLD) configured to execute logic functions relating to human safety requirements of the external system independently of the microcontroller and to provide address decoding, input/output addressing, and/or registers for the microcontroller. The instrument further includes one or more I/O modules that are operatively coupled to the logic card to communicate monitor signals and/or control signals from the logic card to the external system.