Northern UTA220/UTA220k - Manual (Page 123)

UTA220/UTA220k
14-3
Diagnostics
Figure 14-3. Local Loopback Test
To initiate the test, select the LOCAL LOOP 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 may be used. Data from the local DTE will be echoed back
to the sender and the CTS pin follows the RTS pin and the
DSR, DCD and RI pins follow the DTR pin. The DTE portion
of the test verifies the operation of the DTE, the DTE cable the
DTE interface in the UTA220 and of the data buffers in the
UTA220. The test is successful if the data is successfully
echoed back to the sender. A BERT device can be helpful in
checking for data errors.
Digital Loopback Test
Digital loopback loops the ISDN B-Channel data normally
sent to the local DTE (Figure 14-4). Any B-Channel data
received by the UTA220 is processed by the rate-adaptation
protocol, and then echoed back out the B-channel to the
sending unit. This test is useful in diagnosing the DTE,
UTA220, switch ISDN line, and remote unit. Run this test if
you encounter data errors after a call is placed successfully.