363-206-295
Operations Interfaces
Issue 1 December 1997 6-13
Office Alarms 6
The DDM-2000 OC-12 Multiplexer provides relay contacts for wiring to the office
audible and visual alarms. Contacts are provided for each alarm condition: CR
(critical), MJ (major), and MN (minor).
The MJ and CR contact closures are designed to allow these office alarms to be
ORed together and reported as an office MJ alarm.
The CR alarms are fail-safed against power failures. They are activated even if the
shelf loses both power feeders.
The audible office alarms for a given site are silenced through activation of the
ACO function. Visual alarms are not extinguished by the ACO function.
An alarm hold-off delay is provided, to prevent transient failures from causing
unnecessary maintenance activity. The office alarms will not be activated unless a
condition of greater duration than the alarm hold-off delay occurs. When a failure
clears, an alarm clear delay prevents premature clearing of the alarm.
As with the user panel indicators, when multiple alarms are active, the highest
level office alarm (audible and visual) is activated. When the highest level alarm
clears, the office alarm "bumps down" to the next highest level active alarm.
If the ACO function has been activated to silence all active audible alarms, then
when a "bump down" occurs the audible alarms remain silent. (That is, the lower
level visual alarm is activated, but the corresponding audible alarm is not re-
activated.) If another alarm occurs while the ACO is active, the highest level
audible alarm is activated even if the new alarm is a lower level condition. (For
example, if a MJ and MN alarm were active and silenced via the ACO and another
MN alarm occurred, the MJ audible alarm would sound.)
See Section 8, "Administration and Provisioning," for more information.
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