Patent ID: 7424641

Claim:
A method for validating operation of a control system, the control system having a first controller operably communicating with a second controller, the first and second controllers having first and second read-only memories, respectively, the method comprising: executing a first software program in the first controller that retrieves a first key value from the second controller; retrieving a second key value from a table using the first key value as an index value, the table being stored in a memory that is accessible by the first software program; executing at least one mathematical operation in the first software program using at least the second key value to obtain a third key value; sending the first and third key values from the first controller to the second controller; determining a first validation value based on the first key value utilizing the second controller; and comparing the third key value to the first validation value using the second controller and indicating that the first software program has executed until completion when the third key value is equal to the first validation value.