Background Maintenance Functions; Equipment Auditing; Hexadecimal Display Control; Watchdog Timer Setting - Nortel Meridian SuperNode SL-100 Reference Manual

6-22 Feature implementation
the display messages utilized (refer to table "Diagnostic test codes and
descriptions" on page 6-21 for test code descriptions):
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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.
555-4001-129 Standard 08.01 November 2000
C0 indicates clock 0 synchronization
C1 indicates clock 1 synchronization
CF indicates clock failure or no established clocking
RST indicates Reset message received
STAT indicates STATUS message received
TEST indicates TEST message received
LOAD indicates LOAD message received (IPE is being loaded)
LCHK indicates LOAD_CHECK message received
RUN indicates RUN message received
LERR indicates error occurs while loading the software load
RERR indicates error occurs while trying to run from DRAM
SW indicates software takes over from firmware