Apparatus usable with different circuit board variants, with detection of currently-installed variant

A method for operating an apparatus that comprises a plurality of apparatus components collectively configured to be operated to produce an apparatus action, and a controller configured to operate said apparatus components to produce said apparatus action, said method comprising:

• providing, among said apparatus components, a circuit board that receives an input signal from said controller and that produces a photoelectric barrier output signal to said controller, said circuit board being configured in one configuration variant among multiple configuration variance of said circuit board;
• providing said circuit board with a circuit board input to which said input signal to said photoelectric barrier is supplied from said controller, and a circuit board output at which said photoelectric barrier output signal is supplied to said controller, and a delay element electrically connected between said circuit board input and said photoelectric barrier that introduces a delay into said input signal, said delay being matched to the respective variant of said circuit board among said multiple variance;
• and
• in said controller, detecting a characteristic of said delay, selected from the group consisting of an occurrence or non-occurrence of said delay and a magnitude of said delay, and identifying said one variant of said circuit board, among said multiple variants, from the detected characteristic of said delay, and operating said components from said controller to produce said apparatus action dependent on said one variant of said circuit board.