Emerson Rosemount OCX8800A - Page 182

• Out of Service (O/S): The block is not processed. The OUT status is set to Bad:
Out of Service. The BLOCK_ERR parameter shows Out of service.
You can configure the Man, Auto, Cas, and O/S modes as permitted modes for
operator entry.
8.9.7 Alarm detection
A block alarm is generated whenever the BLOCK_ERR has an error bit set.
The types of block errors for the AI block are defined in Block errors.
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:
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 through 7 are advisory alarms of
increasing priority.
8-15 Alarm conditions of priority 8 to 15 are critical alarms of increasing
priority.
8.9.8 Status handling
Normally, the status of the PV reflects the status of the measurement value, the
operating condition of the I/O card, and any active alarm condition. In Auto mode,
F
OUNDATION
™
Fieldbus Manual
December 2022 00809-0500-4880
182 Emerson.com/Rosemount