Micromod MOD: 30ML Functions Data Base Reference - Manual (Page 66)

MOD 30ML Functions
PROCESS ALARM DISPLAY BLOCK
Alarm input (See attribute 17 description)
This is the alarm value that is compared with the trip value to determine when there is an
alarm. It can be an internal value or any source variable used as a block input value (not
operator writeable).
Trip condition (See attribute 5 description)
The trip condition is used to compare the alarm input value with the trip value in the alarm
calculation. The following table shows how the alarm calculation is done for the six
configured trip conditions (When alarm becomes active). Note that hysteresis is not used
when the trip condition is EQUAL or NOT EQUAL. The use of these two trip conditions with
floating point variables may lead to rapid fluctuations.
Trip value (See attribute 12 description)
A trip value having the same data type as the alarm input value. Value is used with the trip
condition and the alarm input value in the alarm calculation
Hysteresis (See attribute 19 description)
For floating point alarms only. A floating point value used to determine when an active alarm
becomes clear (inactive). The value cannot be negative. Since there is often noise
associated with a process variable, hysteresis is used to suppress this noise by preventing
the alarm state from rapidly fluctuating between active and clear.
Alarm priority (See attribute 4 description)
0 to 255. When 0, the alarm unacknowledged field is suppressed and left at false even when
an alarm becomes active. When 1 through 255, the priority value is ignored by this block;
however, it can be used by an external application for alarm reporting (e.g. alarms of different
priorities may be displayed in different colors).
Supress alarm calculation (See attribute 6 description)
NO (not checked) - Alarm active is set true or false as a result of the alarm calculation every
instrument cycle, and alarm unacknowledged is set to true only when the alarm is active this
cycle and was clear the previous cycle. Alarm unacknowledged is set to false when one of
the alarm acknowledgement signals mentioned below (Unacknowledged) is detected.
YES (checked) Alarm calculation is suppressed and alarm active is clear (set to false), alarm
is acknowledged (unacknowledged is set to false), and the output qualities are set to good.
Report alarm events (See attribute 11 description)
If checked, reporting of the following alarm occurrence and acknowledgement events is made
to the System Event queue . Note that this does not affect reporting of block state transitions.
Alarm goes active and unacked.
Alarm goes active but not unacked.
Alarm goes active while unacked.
Alarm goes clear while unacked.
Alarm goes clear while acked.
Alarm cleared by suppression.
Alarm acknowledged.
Alarm globally acknowledged.
Alarm acked by suppression.
Alarm suppressed.
Alarm enabled.
If not checked, no reports are made.
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