Instruction Manual
D103412X012
Detailed Setup—PID Function Block
July 2013
132
Process alarm detection is based on the PV [7] value. You can configure the alarm limits of the following standard
alarms:
High (HI_LIM [51])
High high (HI_HI_LIM [49])
Low (LO_LIM [53])
Low low (LO_LO_LIM [55])
Additional process alarm detection is based on the difference between SP [8] and PV [7] values and can be configured
via the following parameters:
Deviation high (DV_HI_LIM [57])
Deviation low (DV_LO_LIM [59])
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 [47] parameter. The priority of each alarm is set in the following
parameters:
HI_PRI [50]
HI_HI_PRI [48]
LO_PRI [52]
LO_LO_PRI [54]
DV_HI_PRI [56]
DV_LO_PRI [58]
Alarms are grouped into five levels of priority, as shown in table 4‐30.
Table 4‐30. PID Function Block Alarm Priorities
Priority Number Priority Description
(1)
0 The alarm is disabled
1
An alarm condition with a priority of 1 can be recognized by the system. The device monitors the alarm but does not report it
until requested by the host system.
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 Plant Web Alerts.
Application Information
The PID function block is a powerful, flexible control algorithm that is designed to work in a variety of control
strategies. The PID block is configured differently for different applications.
DeltaV Tune
DeltaV Tune quickly and automatically determines optimal tuning parameters for PID control loops. For more
information on DeltaV Tune, refer to DeltaV Books Online or DeltaV documentation.
Block Errors
Table 4‐31 lists conditions reported in the BLOCK_ERR [6] parameter. Conditions in italics are not applicable for the PID
block and are provided only for your reference.
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