Instruction Manual
D103412X012
Detailed Setup—AI Function Block
July 2013
172
Figure 4‐24. Analog Input Function Block Schematic
ANALOG
MEASUREMENT
ACCESS
ANALOG
MEAS.
CHANNEL
SIMULATE
CONVERT
STATUS
CALC.
OUT_D
OUT
PV
ALARM
DETECTION
ALARM_TYPE
ALARM_HYS
LOW_CUT
HI_HI_LIM
HI_LIM
LO_LO_LIM
LO_LIM
OUT_SCALE
XD_SCALE
FIELD_VAL
IO_OPTS
STATUS_OPTS
CUTOFF FILTER
PV_FTIME
L_TYPE
MODE
NOTES:
OUT_D = BLOCK OUTPUT VALUE AND STATUS
OUT_D = DISCRETE OUTPUT THAT SIGNALS A SELECTED ALARM CONDITION.
FIELDBUS‐FBUS_02A
Process Alarm detection is based on the OUT [8] value. You can configure the alarm limits of the following standard
alarms:
High (HI_LIM [28])
High high (HI_HI_LIM [26])
Low (LO_LIM [30])
Low low (LO_LO_LIM [32])
In order to avoid alarm chattering when the variable is oscillating around the alarm limit, an alarm hysteresis in percent
of the PV [7] span can be set using the ALARM_HYS [24] parameter. The priority of each alarm is set in the following
parameters:
HI_PRI [27]
HI_HI_PRI [25]
LO_PRI [29]
LO_LO_PRI [31]
Alarms are grouped into five levels of priority, as shown in table 4‐53.
Table 4‐53. AI Function Block Alarm Priorities
Priority Number Priority Description
(1)
0 The priority of an alarm condition changes to 0 after the condition that caused the alarm is corrected.
1 An alarm condition with a priority of 1 is recognized by the system, but is not reported to the operator.
2
An alarm condition with a priority of 2 is reported to the operator, but generally does not require operator attention (such as
diagnostics and system alerts).
3-7 Alarm conditions of priority 3 to 7 are advisory alarms of increasing priority.
8-15 Alarm conditions of priority 8 to 15 are critical alarms of increasing priority.
1. The priority classes “advise” and “critical” have no relationship to PlantWeb Alerts.
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