Northern UTA220/UTA220k manual Digital Loopback Test

Diagnostics

Figure 14-4. Digital Loopback Test

To initiate the test, select the DIGITAL LOOPBACK option from the PORT TEST submenu. The UTA220 must be on-line when the test is initiated (a call must be placed) before the unit can loop B-channel data. Any protocol, mode, and DTE rate may be used, although the protocol and DTE rates on the two units must be compatible. The remote unit should be set to the same rate adaptation protocol as the local UTA220, and left in normal data mode (NOT placed in Bilateral test mode). Data sent by the remote UTA220 will be received by the local UTA220, then echoed back to the remote UTA220. The test is successful if the data is correctly echoed back to the sender. A BERT device can be helpful in checking for data errors.

The test should be run in both directions if possible (i.e. use the local UTA220 as both the sending unit and as the loopback unit). If the B-channel data test is successful, it indicates that the local and remote units and network are functioning. If there are errors, the problem could be in any of those elements.

14-4 UTA220/UTA220k