When the E1 status is abnormal, how do the audible alarm and the panel indicator LEDs help locate the fault?

When the E1 status changes, the IDM-120PN emits an audible alarm, the panel indicator LEDs display the corresponding alarm state, and the rack alarm output sends the signal to the equipment room monitoring system. On site, begin troubleshooting with the optical port indicator LEDs; if the optical path is normal, check the E1 channel status, then inspect the service interface cards and the wiring labels. On the network management side, the E1 status and the alarm records can be read through the RS232 or RS485 interface, which shows whether the fault is on the optical path, on the E1 channel or at the subscriber interface. After locating the fault, check the wiring channel by channel against the front panel markings, and disconnect only the faulty tributary for handling, so as to avoid powering off and restarting the unit and widening the impact.