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 computer) |
| Name |
Pin |
Pin |
Pin |
Pin |
| Jumpering 1 |
2 |
3 |
|
|
| Jumpering 2 |
7 |
8 |
|
|
| Jumpering 3 |
1 |
4 |
6 |
9 |