Reference Manual

Unit Description, DXU-21
The DXU is tested for Electro Magnetic Compability (EMC) and
complies with the following standards:
•
Fast transient test: EN 301 489-1, 0.5 kV
• Surge test: ITU-T K.45
Test no. 2.1.1.a (CM), basic level: 1.5 kV
Test no. 2.1.1.b (DM), basic level: 1.5 kV
An EMC environment exceeding the above values requires additional
overvoltage protection of the G.703 interface.
External Alarm Inputs
Through this interface it is possible to connect up to 16 binary alarms.
This interface is found in the upper backplane connector.
The equipment connected to the terminals should be insulated relay
contacts. A closed contact (logic zero) is required to be below 2 kOhm,
and an open contact (logic one) is required to be above 100 kOhm.
The current through a closed 0

contact is 1.2 mA.
The alarm contacts connected to the external alarm inputs should be
insulated and have a current range above 1.2 mA. The voltage between
terminals with an open contact is 24 V DC.
Local Bus
The local bus is a time slot and multidrop bus, where the DXU-21 is
the master of the bus. In this DXU, two identical local buses are
implemented, with common frame synchronization and clock signals.
The interface is accessed through the lower backplane connector. The
local bus is used for TRUs and sTRUs.
Timing Bus
This interface is used for distribution of timing information to the TRUs
through the backplane. The interface is accessed through the lower
backplane connector. The timing bus is only used for TRUs.
External Sync. 0 (Freq. Ref.)
This interface is used for connecting an external frequency reference. It
uses a generic synchronization port for the synchronization information.
Optional Output
This interface enables control of up to eight devices, which can be of
various types.
These outputs are accessed through the upper backplane connector.
Optional Input
This interface enables connection of up to eight internal cabinet signals,
such as alarms.
These inputs are accessed through the upper backplane connector.
EN/LZT 720 0008 R1A
2001-06-26
121 (421)
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