Clarification of the Operation of Alarm Annunciators in an E2 Control System
Document Part # 026-4214 Rev 1 08-JUN-2012 Page 7 of 8
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technical bulletin
Alarm(s) cleared from Annun - The clear command was issued from the front panel of the
alarm annunciator (or from a Terminal Mode user connecting to the annunciator).
A Clear All Advisories command (
from the annunciator or advisory log) also works
from either the annunciator log or the non-annunciators advisory log. If a Clear All Adviso-
ries is requested from the alarm annunciator, the Alarm(s) cleared/reset from Annun
notice will only be written once for each non-annunciator E2 that had advisories cleared by
the operation.
Log Size Limits and Advisory Replacement
Advisory logs in E2 controllers are limited to a maximum of 200 entries. For an E2s own advi-
sory log, this is usually sufficient to keep a reasonable amount of recent advisory data. How-
ever, depending on the number of E2s on the network and the frequency at which they
report advisories to the annunciator, it is possible the annunciator log may quickly reach its
maximum and be forced to drop advisories that occurred not too long ago to make room for
brand new advisories.
The annunciator log follows a set of rules to determine which advisories are removed to
make room for new advisories when the maximum limit has been reached. These rules are
designed to preserve the most important entries in the annunciator log (active alarms and
failures, for example) by dropping the less important advisories first.
Whenever the annunciator E2 must place a newly reported advisory into a full annunciator
log, it follows these steps in the order listed below. When the old advisory is removed from
the annunciator log, the new advisory will be written to the top of the annunciator log. If
multiple advisories are being reported, the annunciator log follows the same process with
each alarm, processed one at a time.
1. Some advisory types, such as high and low temperature alarms for generic I/O points,
can have advisories whose types are failures, alarms, or notices, even though the mes-
sage is the same. For example, a high case temperature may be programmed to send a
notice for temperatures above 0°F, an alarm for temperatures above 10°F, and a failure for
temperatures above 20°F. If the new advisory type is a failure and the annunciator log
already has an alarm or notice that has the same alarm message and unit/application of
origin, the annunciator log will remove the old alarm or notice to make room for the fail-
ure.
2. If #1 does not result in a match, look in the annunciator log for the oldest advisory of any
type (alarm, notice, or failure) whose status is "return to normal" or reset to normal (in
E2 versions 3.04/4.04 and above). If a return-to-normal is found, the E2 will remove it to
make room for the new advisory.
3. If #2 does not result in a match, look in the annunciator log for the oldest acknowledged
advisory of any type (alarm, notice, or failure). If an acknowledged advisory is found, the
E2 will remove it to make room for the new advisory.
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