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TimeHub 5500 User’s Guide
097-55501-01 Revision M – January 2009
Chapter 1 Description
Expansion Shelf
Output Driver Cards and Output Connector Modules
Each Output Driver card is associated with its Output Connector card by the letter
groups (A through H) on the front and rear panels. Each letter group has two Output
Driver card slots and two Output Connector module locations. The two Output
Driver card slots are redundant; if two cards are installed and one is disabled, the
other card maintains the outputs. The two Output Connector cards are
not
redundant; each card supports 20 output channels.
Two Output Connector cards are required to support the 40 outputs generated by
the Output Driver card. The upper (top) module provides outputs 1 through 20 for
that particular letter group, and the lower module provides outputs 21 through 40 for
that same letter group. If 20 or fewer outputs of the same type are desired, there is
no need to load both Output Connector module locations.
The Output Driver cards have LEDs that indicate when an associated Output
Connector module is installed on the rear panel of the shelf. Indicators are provided
for ports 1 through 20 and ports 21 through 40. If neither the CC nor DS1 LED is lit,
then an Output Connector module is not installed.
Redundancy Considerations
The interconnections between the Master and Expansion shelf are designed to
support redundancy in several areas. Each area is independent of the others; if one
type of redundancy is lost the other areas of redundancy are not compromised.
Clock Redundancy
The two Clock cards in the Master shelf provide the Expansion shelf with clock
timing, framing, and communication. If either Clock card is removed, the Expansion
shelf continues to receive the necessary signaling from the other Clock card. This is
essentially the same way Clock cards provide redundant timing to Output cards on
a Master shelf; the redundant clock signaling is conveyed between shelves via the
link cables.
Link Cable Redundancy
Each link cable conveys identical information from the master shelf to the
Expansion shelf. Master shelf CLK1 and CLK2 signaling is present on both link
cables; if one link is broken, the Expansion shelf can still receive timing from the
Clock card(s) installed in the Master shelf.
Expansion Controller Card Redundancy
Each EC card receives complete signaling information from both link cables. When
both links are present, each EC card is receiving two sets of identical signaling. If
either EC card is removed, the remaining EC card provides all of the necessary
signaling between the output cards in the Expansion shelf and the clocks in the
Master shelf.