Comtrol RocketPort USB Serial or Modem Hub Driver Installation with Windows 98 - Manual (Page 22)

Troubleshooting 22
Note: Unavailable signals appear dimmed and lowercase; available signals are green and uppercase.
Note: If the COM port does not exist or if it is currently being used by another program, a Create File
Error message appears.
4. Place a loopback plug on the COM port you want to test. Make sure all connectors are seated firmly. If you
need to build loopback plugs, see the
Hardware documentation .
Note: From the Port menu, select Send Test Data. The program sends out a repeating data stream.
Note: If the loopback plug is in place and the port is working correctly, the test data should be echoed back
to the screen. If the loopback plug is not in place or the port is not working correctly, no data or
garbled data is echoed back to the screen. If no characters appear, try putting the loopback plug on
an adjacent port. It may be that you have the ports mixed up.
5. To stop sending data, select Send Test Data again.
Note: It takes a few moments for the buffer to empty and the data to stop displaying on the screen.