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Installation and Setup
Station Clock/Cascade Port Connection
The Station Clock and Cascade Port functions of the SC 553 DSU are mutually exclusive in all
housings, since each employs the same connector. The connector functions are
•
Input port for a Station Clock signal when that is the selected method of Transmit Timing for
the DSU.
•
Cascade Port when the DSU is equipped with the optional Cascade Interface card.
In a MultiPak enclosure the connector for these functions is the lower of the two RJ48 jacks for the
slot that contains the SC 553 DSU.
In an SC 2000 shelf the connector for these functions is the NTWK B RJ48 jack for the slot that
contains the SC 553 DSU.
Zone 1 of an SC 5000 shelf back panel has either 16 RJ48 jacks, labeled J33 through J48, or three
50-pin connectors, labeled J20 through J22 to support these functions.
As shown in
Figure
responds to shelf slot 16. Appendix B, Interface Signals ,
jacks.
On the 50-pin connector back panel, J20 supports Station Clock or Cascade connections for slots
1–6, J21 supports slots 7–13, and J22 supports slots 14–16. Appendix B, Interface Signals , Table
B-6 shows the
slot.
Electrical Power Connection
The DSU obtains power directly from its shelf or enclosure. Consult shelf or enclosure
documentation for power and grounding instructions.
External Alarm Indication (SC 2000 shelf Only)
The SC 2000 shelf provides a back panel connector labeled
indication for the enclosure's power supplies and for pc cards installed in the enclosure.
The connector consists of three contacts:
Normal Open, connect to this contact for an external indicator that activates when contacts are
NO –
closed
Common, connected for either type of indicator
C –
Normal Closed, connect to this contact for an external indicator that activates when contacts
NC –
are open
The SC 553 DSU drives the contacts when any of its defined alarm conditions occurs, as long as
the alarm is not configured to be masked. Consult SpectraComm 2000 Installation and Operation
(010R358-000-01) for more detailed instructions on use of the alarm contacts.
DSU Addressing
The network management system employs a slot-line-drop method of addressing. The DSU slot
address is the number of the slot it occupies in the SC 5000 shelf or MultiPak enclosure. Its line
address is always 1, the DSU is drop 0 for its line, and at the far end of the point-to-point circuit the
remote DSU is drop 1.
076R155-000
Issue 7
2-1, J33 on the dual RJ48 back panel corresponds to shelf slot 1 and J48 cor-
conTable B-6
connector and pins an SC 553 DSU employs when installed in each
SpectraComm 553 Fractional T1 DSU
Installation and Operation Manual
Installation Procedures
Table B-3
shows pin assignments for those
that supports external alarm
ALARM
2-7
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