Patent ID: 7890557

Claim:
A system for reliably acquiring input values, comprising: an operator device; and a failsafe arithmetic unit, wherein the operator device comprises: a first display for displaying a first value input via an input device; a communication device for a unencrypted transmission of the first value together with an identification value, to the arithmetic unit; a first arithmetic processor for converting a second value into a third value, the second value communicated by the failsafe arithmetic unit to the operator device; a second display for displaying the third value; and a third display for displaying a fourth value input via the input device, the first arithmetic processor configured to convert the fourth value into a fifth value, the communication device configured for an unencrypted transmission of the fifth value together with the identification value, to the failsafe arithmetic unit, and the failsafe arithmetic unit comprises: a memory for storing the first value and for storing control and limit values; a first comparator for the comparing the identification value to at least one of the stored control values; a second comparator for comparing the first value to the limit values; a second arithmetic processor for converting the first value into the second value; a transmission unit for an unencrypted transmission of the second value to the operator device; and a third comparator for comparing the fifth value to the first value.