An inverter comprises a first pair of semiconductor devices with switched terminals that are coupled in series between a positive terminal and a negative terminal of a direct current bus. An analog interface adjusts a voltage levels at measurement nodes associated with control terminals of the semiconductor devices. An analog-to-digital converter has analog inputs for receiving the adjusted voltage levels of the measurement nodes and outputting corresponding digital count data for each measurement node. A data processor is adapted to detect the fault or absence of a fault in the inverter based on the conformity of the digital count to one or more reference ranges stored in a data storage device for corresponding switch states of the semiconductor devices.