Standard DB9 COM port pinout: pc(host) with usb to RS232 terminal device(slave) 2- RXD(yellow), 3-TXD(orange),5-GND(GND), 7-RTS(green),8-CTS(brown), 1/4/6/9-NC. Length: 6ft, The other application of the usb rs232 db9 female cable is for PC(host) - device(slave), most of this application is 2-RX, 3-TX, 5-GND. Standard DB9 COM port pinout(pc with usb to RS232 terminal device):2- RXD(yellow), 3-TXD(orange),5-GND(GND), 7-RTS(green),8-CTS(brown), 1/4/6/9-NC. Null modem pinout(laptop pc with usb communicate with destop pc(with DB9 com port)): 2-TXD(yellow), 3-RXD(orange),5-GND(GND), 7-CTS(green),8-RTS(brown), 1/4/6/9-NC.