Description
Original instructions
Function description
The function block PI_B depicts a PI-algorithm with a mixed structure (series/parallel). Its functions derive from function block PIDFF. These functions enable the function block to perform most classical control applications, without compromising user friendliness or using too many system resources. However, for difficult control tasks requiring extended control functions, the PIDFF block should be used.
EN and ENO can be configured as additional parameters.
Functions
The most important functions of function block PI_B are as follows:
Extended functions
As is the case with PIDFF these functions can be extended by using various additional function blocks:
Representation in FBD
Representation:
Representation in LD
Representation:
Representation in IL
Representation:
CAL PI_B_Instance (PV:=ProcessValue, SP:=SetPoint,
    RCPY:=CopyOfRealAction, MAN_AUTO:=OperatingModeFlag,
    PARA:=Parameters, TR_I:=InitializationInput,
    TR_S:=InitializationOrder, OUT:=AbsoluteOutput,
    OUTD=>IncrementalOutput,
    MA_O=>CurrentBlockOperatingMode, DEV=>ValueOfDeviation,
    STATUS=>StatusWord)
Representation in ST
Representation:
PI_B_Instance (PV:=ProcessValue, SP:=SetPoint,
    RCPY:=CopyOfRealAction, MAN_AUTO:=OperatingModeFlag,
    PARA:=Parameters, TR_I:=InitializationInput,
    TR_S:=InitializationOrder, OUT:=AbsoluteOutput,
    OUTD=>IncrementalOutput,
    MA_O=>CurrentBlockOperatingMode, DEV=>ValueOfDeviation,
    STATUS=>StatusWord) ;
Parameter description PI_B
CAUTION
UNEXPECTED BEHAVIOR OF APPLICATION
Do not set the datatype of the PARA input parameter to constant, in the general attributes tab of the Data Properties window.
Failure to follow these instructions can result in injury or equipment damage.
Input parameter description:
Parameter
Data type
Meaning
PV
Process value
SP
REAL
Setpoint
RCPY
REAL
Copy of the effective actuator position
MAN_AUTO
Controller operating mode:
"1" : Automatic mode
"0" : Manual mode
PARA
Parameter
TR_I
REAL
Initialization input
TR_S
BOOL
Initialization command
Input / output parameter description:
Parameter
Data type
Meaning
OUT
REAL
Actuator output
Output parameter description:
Parameter
Data type
Meaning
OUTD
REAL
Differential output Difference between the output of the current and previous execution
MA_O
BOOL
Current operating mode of the function block:
"1": Automatic operating mode
"0": other operation mode (i.e. manual or tracking mode)
DEV
REAL
Deviation value (PV - SP)
STATUS
Status word
Parameter description Para_PI_B
Data structure description
Element
Data type
Meaning
id
Reserved for autotuning
pv_inf
Lower limit of the process value range
pv_sup
REAL
Upper limit of the process value range
out_inf
REAL
Lower limit of the output value range
out_sup
REAL
Upper limit of the output value range
rev_dir
"0": direct action of the PID controller
"1": opposite action of the PID controller
en_rcpy
BOOL
"1": the RCPY input is used
kp
REAL
Proportional contribution (gain)
ti
Integral time
dband
REAL
Dead zone on deviation
outbias
REAL
Manual adjustment of static deviation