The GD series of metal sheet double feed detectors provides a reliable and accurate means of sensing double fed sheets of any metal that is 0.01mm or more thick. A simple teaching function allows for quick sensitivity setting and maintenance. Three types of heads are available from the small object sensing GD-3 to the long sensing range GD-20. The user-friendly sensor controller provides a seven LED display that indicates the sensing level. Also, the unit has built-in RS-232 support with an 8 bank internal memory for simple product changeover. Errors can quickly be determined by viewing the self-diagnosis display or by utilizing the self-diagnosis output. This feature communicates an error code that will indicate which of the seven monitored functions is at fault.