The LOOP LINE command tests the communication hardware and software
for a synchronous link.

FORMAT:

        LOOP line-component parameter [...]

LINE COMPONENT:

        LINE line-id

        Specifies the line that is to be tested.  Enter the line-id in
        the format SYN-n, for example, SYN-0.

        The LOOP LINE command cannot be used for channel-attached
        communication links.

Additional information available:

AT_CONTROLLERAT_CABLEAT_MODEM

Example

Tests the communications device.  If this test fails, there is a fault
with the communications device.

If this test is successful, use the AT CABLE parameter to try to
isolate the problem.

Format:  AT CONTROLLER

Tests the cable from the Gateway to the cable loopback connector.  If
this test fails, there is a fault with the cable.  Replace the cable.

If this test is successful, use the AT MODEM parameter to try to
isolate the problem.

Format:  AT CABLE

Tests the local or remote modem.  Set the modem you want to test into
analog loopback test mode.  Then enter the LOOP LINE line-id AT MODEM
command.  If this test fails, repair or replace the modem.

If this test is successful, but you still have a problem, you may have
to arrange for tests to be carried out from the IBM side.  Speak to
your IBM system programmer to arrange for such tests.

Format:  AT MODEM

SNANCP> SET LINE SYN-0 STATE OFF
SNANCP> LOOP LINE SYN-0 AT CONTROLLER

After setting line SYN-0 to the OFF state, the LOOP LINE command tests
the communication device.