Description
Original instructions
Function description
This function block is suitable for simple two point controls.
Control of the actuator proceeds according to the direction of the actual/setpoint value deviation in relation to the upper and lower threshold.
EN and ENO can be configured as additional parameters.
Properties
The control block has the following properties:
Representation in FBD
Representation:
Representation in LD
Representation:
Representation in IL
Representation:
CAL STEP2_Instance (PV:=ProcessValue, SP:=SetPoint,  
    MAN_AUTO:=OperatingMode, PARA:=Parameters, 
    OUT=>LogicOutput, DEV=>Deviation, 
    MA_O=>CurrentOperatingMode, STATUS=>StatusWord)
Representation in ST
Representation:
STEP2_Instance (PV:=ProcessValue, SP:=SetPoint,  
    MAN_AUTO:=OperatingMode, PARA:=Parameters, 
    OUT=>LogicOutput, DEV=>Deviation, 
    MA_O=>CurrentOperatingMode, STATUS=>StatusWord) ;
Parameter description STEP2
Input parameter description:
Parameter
Data type
Meaning
PV
Process value
SP
REAL
Setpoint
MAN_AUTO
Controller operating mode:
"1" : Automatic mode
"0" : Halt mode
PARA
Parameter
Output parameter description:
Parameter
Data type
Meaning
OUT
BOOL
Logical output
DEV
REAL
Deviation ( PV -SP )
MA_O
BOOL
Current operating mode of the function block
(0: Halt, 1: Automatic)
STATUS
Status word
Parameter description Para_STEP2
Data structure description
Element
Data type
Meaning
dev_ll
Lower deviation threshold (≤ 0)
dev_hl
REAL
Upper deviation threshold (≤ 0)
pv_inf
REAL
Lower limit of the process value range
pv_sup
REAL
Upper limit of the process value range