6 PID function block (PID controller) PROline Prosonic Flow 93 FOUNDATION Fieldbus
194 Endress+Hauser
6.6 Limit values
The limit values are based on the value of the process variable PV, (see Page 212).
If the process variable PV exceeds or undershoots the defined limit values, an alarm is
sent to the fieldbus host system via the limit value process alarms.
The following limit values can be defined:
6.7 Alarm detection and processing
Process alarms provide information on particular block statuses and block events.
The status of the process alarms is communicated to the fieldbus host system via the
BLOCK_ALM parameter, (see Page 201). The ACK_OPTION parameter,
(see Page 197), specifies whether an alarm must be acknowledged via the fieldbus
host system.
The following process alarms are generated by the PID function block:
• Block process alarms
A block process alarm is triggered via the BLOCK_ERR parameter, (see Page 201).
The BLOCK_ALM parameter (see Page 197) is used to show the block process
alarms and communicate them to the fieldbus host system. The following block
process alarm can be generated by the PID function block:
– OUT OF SERVICE
• If the option of the process alarm (BLOCK ALM) has not been enabled in the
ACK_OPTION parameter, (see Page 197), the process alarm can only be
acknowledged in the BLOCK_ALM parameter, (see Page 197).
• Limit value process alarms
If a limit value is violated then the priority specified for the limit value alarm is checked
before the limit value violation is communicated to the fieldbus host system.
The priority that specifies the action in the event of an active limit value violation is
determined by the following parameters:
The status of the limit value process alarms is communicated to the fieldbus host
system via the following parameters:
If the option of a limit value process alarm has not been enabled in the ACK_OPTION
parameter, (see Page 197), then this must be acknowledged directly in its parameter
(see list).
Note!
The ALARM_SUM parameter, (see Page 199), shows the current status of all the
process alarms.
– HI_HI_LIM
(see Page 205)
– HI_LIM
(see Page 206)
– LO_LO_LIM
(see Page 208)
– LO_LIM
(see Page 207)
– DV_HI_ALM
(see Page 202)
– DV_LO_ALM
(see Page 204)
– HI_HI_PRI
(see Page 206)
– HI_PRI
(see Page 207)
– LO_LO_PRI
(see Page 207)
– LO_PRI
(see Page 209)
– DV_HI_PRI
(see Page 203)
– DV_LO_PRI
(see Page 204)
– HI_HI_ALM
(see Page 205)
– HI_ALM
(see Page 205)
– LO_LO_ALM
(see Page 208)
– LO_ALM
(see Page 207)
– DV_HI_ALM
(see Page 202)
– DV_LO_ALM
(see Page 203)
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