DM16E1 / DM4E1 Operation and Installation Manual - 204-4001-19
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In case of a high-priority alarm and a subsequent low-priority condition, the latter is ignored, and only the
high-priority alarm remains (indicated in Latched Alarms in case of management via the Terminal port).
The following table illustrates the alarm conditions according to their priority and generating interface.
Priority
Condition
Loss of carrier in aggregate
No frame synchronization on the aggregate
Reception of AIS on the aggregate
Alarm indication on the remote unit
Reception of AIS on tributary E1
Loss of LINK by 10/100BaseT Bridge
CT128 OFF (if enabled)
CT113 OFF (if enabled)
Failure in one of the power supplies
Loss of carrier on tributary E1
CT105 OFF (if enabled)
CT108 OFF (if enabled)
LOW
HIGH
Table 18. Alarm conditions
Both the led on the front panel and the indication via the Terminal port or DmView signal alarm conditions.
If the alarm-generating source is not present after an alarm reset (see chapter 3 for further information),
then the alarm signal will be removed.
For the visualization of possible alarm causes, check the leds on the frontal panel or use the Terminal port.
Once all the alarming conditions are solved, the alarms must be reset. If a condition is not solved, the
alarm led will not turn off. However, there may be a change in the condition of the alarm (from high to low
priority), according to the remaining alarming conditions.
12.3. Input of External Clock
The DM16E1/DM4E1 cards are provided with a IEC169/13 (or BNC) connector on the rear panel for the
connection of an external clock source at 2048kHz (according to G.703). This is used by the E1 interfaces
in case of failure in the synchronization recovery of an E1 interface. In case of failure in the external clock
signal, the equipment will automatically commute to the internal clock.
The clock source is selected via the Terminal port or via the DmView. Located by this connector is the E1C
strap, with which it is possible to remove the end of the input, so that several devices can be connected
simultaneously and only one of them presents a load of 75 ohms.
E1C position
Load of 75ohms
OFF
Off
ON
On (factory standard)
Table 19. E1C straps
The PDH DM4E1 and DM16E1 equipment do not need synchronization via the clock’s external reference.
The E1 channel’s clocks are independently propagated to the remote equipment. The use of an external
clock’s input for: AIS Generation (E1 G.703 output) in case of aggregate synchronism loss, transmission
Clock for interface V.35.