Method for operating a safety control device

A safety control device comprising:

• a first and a second calculation unit arranged so as to form a redundant control unit,
• an input unit designed for receiving an input signal and for determining a floating point value depending on the input signal, and
• an output unit designed for driving an actuator,
• wherein the input unit is connected to each of the first and second calculation units for feeding the floating point value to the first and second calculation units,
• wherein each of the first and second calculation units are configured to determine an input interval as a function of the floating point value and to determine a result interval as a function of the input interval by applying a first calculation algorithm to the input interval, the first calculation algorithm being based on interval arithmetic,
• wherein the first and the second calculation units are connected for comparing the result intervals and for determining an output value as a function of the result intervals, and
• wherein at least one of the first and second calculation units is connected to the output unit for outputting an output signal as a function of the output value, said output signal driving the at least one actuator.