There is also an acoustic signal.
Short beep: twice after (re)-initialisation, three times in case of error (invalid card, unsuccessful parameterisation).
Long beep: once after voltage on, once after a valid card has been read.
LED „Power" constantly on in case of proper power supply, otherwise off.
LED “OK": blinking when no initialisation has yet taken place, permanently off after correct initialisation, briefly on (0.5 s) for correct reading process.
LED „Error": on for about 1 s in case of error (invalid card).