A control system to control an electric drive, the control system comprising: a main controller operable to execute instructions including the computation of a value based on at least one parameter; and a monitoring module operable to provide queries from time-to-time to the main controller, operable to evaluate an accuracy of an answer to a query returned to the monitoring module by the main controller, and operable to execute a protective state entry procedure in response to a determination that a number of answers returned by the main controller that are determined to be incorrect exceeds a threshold value.