The SAFE Inteligent
Loop Dropout Panel (SILDP), automatically
monitors RIM loops. Its primary benefit is that it
permits the addition of many miniloops to a main RIM
loop -- with no danger of losing everything on a loop
due to one device or miniloop line failure. The SILDP
has 16 zones, each capable of monitoring, shunting or
restoring the outgoing and incoming leg of a
miniloop. Each zone is capable of automatic or manual
operation. There is a 3-position switch for each
zone, which determines the mode of operation, and a
per-zone, bicolor LED showing the current status of
each miniloop. With the switch in the center positon,
operation is automatic and the LED indicates the
status of the loop (green is good, red is fault).
With the switch in the up position, the miniloop is
locked into the main loop whether the miniloop is
good or bad, and the LED flashes green to indicate
this condition. (This allows diagnostic work to be
done on the system. With the switch in the down
position, the miniloop is manually shunted out of the
main loop and the LED flashes red.
In normal operation
the SILDP does not interfere with its miniloops. It
only monitors the communications going into the
miniloops and the communications coming back on the
return legs. While the communications are normal, the
zone LED is green indicating a normal loop. If the
SILDP detects communications going into a miniloop
but nothing returning, it knows that that miniloop is
broken. The SILDP then shunts that miniloop out of
the main loop and lights the red LED indicating that
miniloop is bad. This restores the rest of the main
loop. Meanwhile, the SILDP begins talking to the bad
miniloop with the same communications format the host
computer would use for a bad loop. The entire
detection and switch over process takes about 1-1/2
minutes. If the miniloop problem is corrected, the
SILDP automatically detects it, and restores the
miniloop back into the main loop again.
The SILDP is designed
to fit into a standard 19" rack and occupies
only two inches of vertical space. Connections are
made through two 50-pin telephone-type connectors. To
facilitate connection to existing systems, an
interface panel is available that plugs into the two
50-pin connectors. RS232 connectors and cables are
then connected directly to the miniloop modem. This
assures minimum downtime while installing the SILDP.
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