Flowserve MX FOUNDATION Fieldbus Field Unit - Manual (Page 37)

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MX/QX FOUNdaTION Fieldbus Field Unit FCd LMENIM2330-01 – 08/11
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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 PV value. One 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)
Additional process alarm detection is based on the difference between SP and PV values and can be
configured via the following parameters:
• Deviation high (DV_HI_LIM)
• Deviation low (DV_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
• DV_HI_PRI
• DV_LO_PR
Priority Number Priority Description
0 The priority of an alarm condition changes to 0 after the condi-
tion 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.
Status handling
If the input status on the PID block is bad, the mode of the block reverts to Manual. In addition, one
can select the target to Manual if bad IN status option to direct the target mode to revert to manual.
Status option can be set in Manual or Out of service mode only.