Page 302 of 906 NT5D33 and NT5D34 Lineside E1 Interface cards553-3001-211 Standard 3.00 August 2005seconds, neither a loss of signal, out-of-frame condition, or blue alarmcondition occurs.If a repeating device loses signal, it immediately begins sending an unframedsignal of all ones to the far-end to indicate an alarm condition. This conditionis called a blue alarm, or an Alarm Indication Signal (AIS). If an AIS isdetected for more than two seconds, a level 2 alarm is declared, and silence issent on all receive timeslots. The alarm is cleared if, after two seconds, neithera loss of signal, out-of-frame condition, or blue alarm condition occurs.Alarm DisableThe Alarm Disable (A D) command disables the external alarm contacts.When this command is typed, the MMI displays the message AlarmsDisabled and the MAINT LED lights. In this mode, no yellow alarms are sentand the LEI does not enter line processing mode. Alarm messages are sent onthe MMI terminal and the LED continues to indicate alarm conditions.Alarm EnableThe Alarm Enable (A E) command does the reverse of the Alarm Disable(A D) command. It enables the external alarm contacts. When this commandis typed in, the MMI will display the message Alarms Enabled. In this mode,yellow alarms can be sent and the LEI can enter line processing mode.Clear AlarmThe Clear Alarm (C A) command clears all activity initiated by an alarm:the external alarm hardware is deactivated (the contact normally open isreopened), the LED goes out, an entry is made in the alarm log of the date andtime the alarm was cleared, and line processing ceases (for alarm level 2only). When this command is typed, MMI displays the message Alarmacknowledged. If the alarm condition still exists, an alarm is declared again.Display AlarmsA detailed report of the most recent 100 alarms with time and date stamps canbe displayed by entering the Display Alarms (D A) command into the MMI,which will cause a screen similar to Figure 53 on page 303 to appear.
