... a communication port conversion module of USB<->RS232, USB <-> RS485, USB<->LINK (Smartgen special). 1 ... this light will flash.3, POWER LED: When the SG72 module successfully connect to USB, this light will be illuminated.4 ... , USB interface: Connect SG72 module to the USB interface on PC by the data line ... This is a generic DB9 serial communication interface. sg72 module