Specifications

Reference Guide
4-25
System Configuration and Operation Alarms
4.7.3 Alarm Modifiers
Each alarm may also be designated as
I=info
,
m=minor
,
M=major
or
C=crit
. The filter
modifier appears on both the active alarm and alarm history screens.
If the system has an External Alarm card (optional), the occurrence of any alarm designated
as
crit
will trigger a form-C relay contact on the External Alarm card. The relay contact action
sets off an annunciator or lamp at the equipment site. Similarly, the occurrence of any alarm
designated as
major
triggers a different contact and activates another external indicator. Refer
to the Alarm Card Reference Guide for more information on the External Alarm cards.
4.7.4 Alarm Cutoff (ACO)
The ACO (Alarm Cutoff) security feature is used by the system to alert an operator to alarms
that clear themselves while the system is unattended. The ACO option settings are
aco-on
and
aco-off
. If ACO is set to report or log alarms, any alarm set to report or log with a major
modifier brings up an additional alarm message on the screen. You must manually clear this
message, which is the ACO alarm message (depends on whether or not CPU is set for latch or
CUR). The ACO is used with the node port of the Interface card. It can also trigger an external
alarm device, such as a bell or lamp, that must also be manually cleared.
All ACO alarms must be cleared from the Interface card screen. ACO alarms can be cleared
automatically or manually.
4.7.5 Backplane Out of Service (BP_OOS)
The host CPU polls each card periodically for a variety of information and alarm status. The
card responds with a multi-field message to the host with such information as alarm condition
(either active or not and type of alarm), slot number, etc. Alarms are automatically set or
cleared based on the contents of these messages returned by each card. For the BP-OOS alarm,
the slot number reported from a card is corrupted for an OOS type alarm. The CPU reports
BP-OOS when it indexes outside the boundaries of a defined alarm.
Possible causes for this alarm type include:
1. Improper grounding of the system. Floating lines on the backplane can cause the
message between card and host to be corrupted, so proper grounding can have a positive
effect on removing this condition.
2. Improper seating of cards may cause an intermittent error where the CPU receives
incorrect data from the card.
3. Defective serial memory on a card or defective NVRAM on the Interface card can also
cause this condition to occur in the field.