Northern UTA220/UTA220k - Manual (Page 122)

14-2
UTA220/UTA220k
Diagnostics
PORT TESTS
Port communications tests are initiated and terminated via the
front panel under the PORT TEST submenu of the
DIAGNOSTIC OPTIONS. The following section describes
each of the tests, when to use them and what it means if they
fail.
Local Terminal Loopback
Local terminal (DTE) loopback loops data back to the DTE by
connecting the TD and RD pins so that whatever the DTE sends
is echoed back (Figure 14-2).
Figure 14-2. Local Terminal Loopback Test
To initiate the test, select LOCAL TERMINAL LOOPBK
option from the PORT TEST submenu. The UTA220 may be
on-line or off-line when the test is initiated. Any protocol,
mode, and DTE rate can be used. The test is successful if the
data is successfully echoed back to the DTE. A BERT device
can be helpful in checking for data errors. This test verifies the
operation of the DTE, the DTE cable, and the DTE interface
of the UTA220.
Local Loopback Test
Local loopback loops data from the local terminal back to the
terminal so that whatever the terminal sends is echoed back
(Figure 14-3). Also the RTS pin is echoed on the CTS pin and
the DTR pin is echoed on the DSR, DCD, and RI pins. Run
this test if you are encountering data errors before and after
data calls are placed. This test is useful in diagnosing the DTE
and the UTA220.