6-22 Feature implementation
555-4001-129 Standard 08.01 November 2000
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C0 indicates clock 0 synchronization
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C1 indicates clock 1 synchronization
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CF indicates clock failure or no established clocking
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RST indicates Reset message received
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STAT indicates STATUS message received
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TEST indicates TEST message received
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LOAD indicates LOAD message received (IPE is being loaded)
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LCHK indicates LOAD_CHECK message received
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RUN indicates RUN message received
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LERR indicates error occurs while loading the software load
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RERR indicates error occurs while trying to run from DRAM
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SW indicates software takes over from firmware
Background maintenance functions
Equipment auditing
In general, equipment is audited periodically to detect unexpected changes in
operational status. This function audits each line card and terminal at least
once every 15 seconds.
Hexadecimal display control
The controller card has a two-digit hexadecimal display mounted on its
faceplate. This function handles all output directed to this display from other
processes.
Watchdog timer setting
The ability to recover from catastrophic failures is very important. The
controller card has a watchdog timer circuit that resets the board automatically
if it is not cleared periodically by the applications software. This function
clears the watchdog timer on a regular basis. If the watchdog times out, a
catastrophic software failure is assumed and the controller card is reset.
Phase lock loop switching
The IPE must be synchronized to the C-side communication links to
communicate over them. The controller card has a phase lock loop circuit that
accomplishes this synchronization. This function attempts to resynchronize
the card if the phase lock loop loses sync with the C-side links.
