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Reference Manual
00809-0100-4026, Rev HA
Appendix I: Analog-Input block
November 2014
Analog-Input Block
I.6 Alarm detection
A block alarm will be generated whenever the BLOCK_ERR has an error bit set. The types of
block error for the AI block are defined above.
Process Alarm detection is based on the OUT value. You can configure the alarm limits of the
following standard alarms:
High (HI_LIM)
High high (HI_HI_LIM)
Low (LO_LIM)
Low low (LO_LO_LIM)
In order to avoid alarm chattering when the variable is oscillating around the alarm limit, an
alarm hysteresis in percent of the PV span can be set using the ALARM_HYS parameter. The
priority of each alarm is set in the following parameters:
HI_PRI
HI_HI_PRI
LO_PRI
LO_LO_PRI
Alarms are grouped into five levels of priority:
Table I-3. Alarm Level Priority
Priority
number
Priority description
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 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.
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