Northern UTA220/UTA220k manual Digital Loopback Test, Local Loopback Test

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.

UTA220/UTA220k 14-3