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Previous Chapter Mn = KP * (Eν + KI * ΣϒMι (Eι*δTι)) + KΔ * (Eν - Eν-1)/δTν + Mρ
Where:
delM(n) = KP * ((Eν-Eν-1) + Eν * δTν * KI + KΔ * ((Eν -Eν-1)/δTν - (Eν-1 -Eν-2)/δTν-1))
For this record:
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Field Type DCT Initial Access Modify Rec Proc PP
Monitor
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VAL FLOAT No 0 Yes Yes Yes Yes
CVL INLINK Yes 0 No No N/A No
STPL INLINK Yes 0 No No N/A No
SMSL GBLCHOICE Yes 0 Yes Yes No No
PREC SHORT Yes 0 Yes Yes No No
MDT FLOAT Yes 0 Yes Yes No No
KP FLOAT Yes 0 Yes Yes No No
KI FLOAT Yes 0 Yes Yes No No
KD FLOAT Yes 0 Yes Yes No No
EGU STRING Yes Null Yes Yes No No
HOPR FLOAT Yes 0 Yes Yes No No
LOPR FLOAT Yes 0 Yes Yes No No
HIHI FLOAT Yes 0 Yes Yes No No
LOLO FLOAT Yes 0 Yes Yes No No
HIGH FLOAT Yes 0 Yes Yes No No
LOW FLOAT Yes 0 Yes Yes No No
HHSV GBLCHOICE Yes 0 Yes Yes No No
LLSV GBLCHOICE Yes 0 Yes Yes No No
HSV GBLCHOICE Yes 0 Yes Yes No No
LSV GBLCHOICE Yes 0 Yes Yes No No
HYST FLOAT Yes 0 Yes Yes No No
ADEL FLOAT Yes 0 Yes Yes No No
MDEL FLOAT Yes 0 Yes Yes No No
ODEL FLOAT Yes 0 Yes Yes No No
CVAL FLOAT No 0 Yes Yes No No
DM FLOAT No 0 Yes No Yes No
ODM FLOAT No 0 Yes No Yes No
P FLOAT No 0 Yes No Yes No
I FLOAT No 0 Yes No Yes No
D FLOAT No 0 Yes No Yes No
CT ULONG No 0 Yes No Yes No
DT FLOAT No 0 Yes No Yes No
ERR FLOAT No 0 Yes No Yes No
DERR FLOAT No 0 Yes No Yes No
LALM FLOAT No 0 Yes No No No
ALST FLOAT No 0 Yes No No No
MLST FLOAT No 0 Yes No No No
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Name Summary Description
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VAL Setpoint Value, in This is the value that the control algorithm attempts to
engineering units achieve.
CVL Controlled Value This is a link specifying the location of the controlled
Location (input variable. This must be a database link. Each time the
link) record is processed the current value referenced by CVL is
read into CVAL.
STPL Setpoint Location If STPL is a database or channel access link and SMSL is
(input link) CLOSED_LOOP, then VAL is read from STPL. STPL and
SMSL act just like DOL and OMSL.
SMSL Setpoint Mode This is SUPERVISORY or CLOSED_LOOP. VAL is
Select obtained from STPL only when this is CLOSED_LOOP.
By setting this field, the record can be switched between
supervisory and closed loop. Note that closed loop is
useful for cascaded control records.
PREC Display Precision Precision with which to display VAL. This field is used by
record support to supply a value when get_precision
is called.
MDT Minimum Delta Minimum time difference between processing in seconds.
Time, in seconds If this is zero, the minimum time is one clock tick.
KP Proportional Gain
KI Integral Gain, in The number of times per minute that the integral
repeats per minute contribution repeats the proportional contribution.
KD Derivative Gain, in The number of minutes until the derivative contribution
minutes per repeat repeats the proportional contribution.
EGU Engineering Units ASCII string describing Engineering units. This field is
used by record to supply a units description string when
get_units is called.
HOPR High Operating These fields determine the upper and lower display limits
Range for graphics displays and the upper and lower control
limits for control displays. The fields are used by record
support to honor calls to get_graphic_double or
get_control_double.
LOPR Low Operating
Range
HIHI Hihi Alarm Limit These fields specify the alarm limits and severities.
HIGH High Alarm Limit
LOW Low Alarm Limit
LOLO Lolo Alarm Limit
HHSV Severity for a Hihi
Alarm
HSV Severity for a High
Alarm
LSV Severity for a Low
Alarm
LLSV Severity for a Lolo
Alarm
HYST Alarm Deadband These parameters specify hysteresis factors for triggering
monitor callbacks, i.e. monitors specified by calls to
caAddEvent or dbAddEvent. A monitor will not be
triggered until VAL changes by more than the specified
amount.
ADEL Archive Deadband
MDEL Monitor, i.e. value
change, Deadband
ODEL Output Delta This parameter specifies a hysteresis factor for triggering
monitor callbacks for DM, P, I, D, CT, DT, ERR, and DERR.
It refers to the change in DM. Whenever monitors are
triggered for DM, monitors for the other fields are also
triggered.
CVAL Value of Controlled This value is obtained from CVL each time the record is
Variable, in processed.
engineering units
DM Change in This is the value computed by the pid algorithm. It is an
Manipulated increment to be added to the controller output. Note that
Variable in most cases this will be read via the DOL field of an
analog output record. The analog output record will be
configured with OIF set to incremental.
ODM Old DM ODM is used to decide if monitors should be triggered for
DM.
P Proportional Proportional contribution to DM, in engineering units.
contribution
I Integral The number of times per minute that the integral
contribution to contribution repeats the proportional contribution.
DM, in repeats per
minute
D Derivative The number of minutes until the derivative contribtuion
contribution to repeats the proportional contribution.
DM, in minutes
CT Clocks Ticks Clock ticks when previous process occurred.
DT Time difference Time difference in seconds between processing steps.
ERR Error Current error (VAL - CVAL).
DERR Delta Error Change in error since last time step.
LALM Value when last These fields are used to implement the hysteresis factors
monitors for alarm for monitors.
were triggered
ALST Value when last
monitors for
archiver were
triggered
MLST Value when last
monitors for value
changes were
triggered
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upper_alarm_limit = HIHI upper_warning_limit = HIGH lower_warning_limit = LOW lower_alarm_limit = LOLO
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