Start Test Terminal and open one or more ports. (See Starting Test Terminal for more information.)
Attach a loopback plug to the COM port that you
want to test. To build loopback plugs, see the latest Hardware Installation
documentation. See Hardware
Installation Documentation for more information on the location of
this document.
Note: This procedure only describes how to transmit test data
on a single active port. If you intend to transmit test data on more than
one port, you must attach a loopback plug to each COM port that you want
to test and use the appropriate transmit test data buttons as described
above.
Make sure all connectors are seated firmly.
Click the Loopback
button on the port window toolbar to turn off the
Test Terminal loopback option. LPBK
should not appear in the port window status bar. When you are testing
a serial port, and LPBK is deactivated,
any entries you make are passed through the serial port to the interface
box or fanout cable.
Note: Some Comtrol products do not support internal loopback
(for example, 1-port DeviceMaster).
Select Port
> Send and Receive Test Data
(or click the Send Test Data 
button on the port window toolbar to send test data
to an individual port) to receive test data from an individual port. Sending & Receiving should appear
in the port window status bar. This is a pass/fail test that checks all
modem control signals.
Pass - If the loopback plug is in place and the port is working correctly, the test data is echoed back to the screen. You should see the alphabet scrolling in a sawtooth pattern (incrementing by one letter for each line of data received until it reaches the letter Z and then it repeats until you stop the test).
Fail - 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.
Note: If no characters appear, try putting the loopback plug on an adjacent port. It may be that you have the ports mixed up.
To stop the test data stream, select Port
> Send and Receive Test Data
(or click the Send Test Data and Receive Test Data
buttons) again. Ready
should appear in the port window status bar.
If further testing is required, select Port
> Loopback Test. This option
requires a loopback plug.
Note: You can only run this test on RS-232 ports. This test
will fail if the port is configured for use as either RS-422 (or RS-485)
because RS-422 (or RS-485) does not have the modem control signals that
are present in RS-232 for which this test is designed. This test cannot
be used on RocketModem products, as there is no loopback plug for the
phone port on the modem.
Click OK
to dismiss the request to place the loopback plug on the port if the loopback
plug is already attached. If the loopback plug is not attached connect
it now and click OK to dismiss
the dialog.
If the loopback plug is in place and the port is working correctly
the system should return the following message: Port
passed the loopback test.
A Loopback failed message appears
under the following circumstances:
You are running the Loopback Test on an RS-422 (or RS-485) port.
The loopback plug is not in place.
A port is not working correctly
You are testing a serial port and have the loopback plug on the wrong port.
If you get a Loopback failed message try the following:
Check the RS mode for the port. It could be that you are trying to run the Loopback Test on an RS-422 (or RS-485) port. The Loopback Test is not supported on the RS-422 (or RS-485) port.
Put the loopback plug on an adjacent port and retry the Loopback Test. It may be that you have the ports mixed up.
Click the OK button to dismiss the dialog box.
If the port failed the loopback test in steps
7-9 and the product is equipped with an external interface box or fanout
cable, click the Loopback button on the port window toolbar to turn on the internal
loopback feature. LPBK appears
in the port window status bar. When LPBK
is activated, commands are looped through the serial port hardware and
never make it to the interface box or fanout cable.
Repeat steps 7-9. If the port now passes the tests, the fault may lie in the interface box or fanout cable. Contact Comtrol Technical Support for assistance.
If you are finished testing ports, close the Test Terminal and restart the applications.