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Chapter 1
Overview
Backplane (Fabric)
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If one of the HSOs outputs does not have the correct amplitude then the RCS uses the other one as the source
of clocks and sends an alarm signal to the RPM indicating which oscillator failed. The green LED is lit on the
good HSO and the yellow LED is lit on the failed HSO.
If an external clock coax is connected from the master backplane clock output MCX connector to the slave
backplane clock input MCX connector then, this overrides any firmware clock selections. The clock source
from the slave backplane will be the master backplane.
If firmware selects the margin oscillator as the source of clocks, then it is the source of clocks as long as there
is no connection to the clock input MCX connector from the master backplane.
If the firmware selects the external margin clock SMB connectors as the source of clocks, then it is the source
of clocks as long as no connection exists to the clock input MCX connector from the master backplane.
Cabinet ID
The backplane receives a 6-bit cabinet ID from the CLU interface connector J64. The cabinet ID is buffered
and routed to each RPM and to each Cell module slot. The RPM decodes the cabinet number from the cabinet
ID and uses this bit to alter the cabinet number bit in the ALBID byte sent to each XBC through the serial bit
stream.
Cell ID
The backplane generates a 3-bit slot ID for each cell slot in the backplane. The slot ID and 5 bits from the
cabinet ID are passed on to each cell module as the cell ID.
Backplane Power Requirements and Power Distribution
The dc supply for the backplane assembly is from the cabinet power supply subsystem through two power
cables attached to the backplane. Connectors for the dc supply input have the same reference designators and
are physically located in the same position as on the Superdome system backplane. The power cables are
reused cable assemblies from the Superdome system and the supply connection is not redundant. One cable is
used for 5V housekeeping supply input and the second cable is used for 48 V supply input.