Method and apparatus for identifying a relative rotation between a rotary unit and a base unit in a drive unit, receiving a command that changes the relative rotation when the command is executed by the drive unit, determining that rotating at least one of the base unit or the rotary unit in a first direction in response to the command results in the relative rotation exceeding a maximum rotation value, and rotating at least one of the base unit or the rotary unit in a second direction opposite the first direction while executing the command. In one example, the drive unit may include cables that transfer power and control signals from the base unit to the rotary unit. Determining whether executing the command results in the relative rotation exceeding the maximum rotation value can ensure the cables are not damaged.