DB9 serial (RS232) loopback. Pinout and signals for building a serial port loopback (Norton)

The PC loopback plug is a useful diagnostic tool. The loopback plug connects serial inputs to serial outputs so that the port may be tested. There is more than one way to wire up a loopback plug - but this is the most common. Used to verify that a port is working. This one works with Norton Utilities: Norton Diagnostics from Symantec.

DB9 pin D-SUB male at the DTE (Computer) DB9 pin D-SUB male (at the computer)

Name Pin Pin Pin Pin
Jumpering 1 2 3
Jumpering 2 7 8
Jumpering 3 1 4 6 9