Serial port Loopback (9 CheckIt)

pinout

Used to verify that a port is working. This one works with CheckIt.

9 pin D-SUB female connector  to the computer

Name Pin Pin Name CD 1 6 DSR CD 1 9 RI RXD 2 3 TXD DTR 4 6 DSR RTS 7 8 CTS

Source:www.pinouts.ru