Most of the engine/generator controllers used today are digital and are designed to provide control of the generator set. The controller system monitors the operation of the engine and generator functions. Typical safety items include low oil pressure, high temperature, engine start over-crank, over/under frequency (speed), low coolant level etc. Modern digital controllers for residential or small business applications are typically a simplified LED indicator a start-stop button with or without auto-start. If the generator has auto-start, the controller can be used to interface with an ATS to start and stop automatically. Usually manual controls are provided on all generators including those with auto-start. Advanced controllers provide real time monitoring of volts, hertz, and amperage in addition to the basic engine/generator safeties and auto-start functions.