Description

Function description

The function block forms a three-point controller, which maintains PID-similar behavior through two dynamic feedback paths.

and can be configured as additional parameters.

Properties

The function block PCON3 contains the following properties:

Operating modes Manual, Halt, Automatic
Two internal feedback paths (delay 1st Order)

Representation in FBD

Representation:

Representation in LD

Representation:

Representation in IL

Representation:

CAL PCON3_Instance (SP:=SetpointInput, PV:=ProcessVariable, 
    MODE:=OperatingModes, PARA:=Parameter, 
    YMAN_POS:=ManManipulated_Y_POS, 
    YMAN_NEG:=ManManipulated_Y_NEG, 
    Y_POS=>PosManipulated_ERR_EFF, 
    Y_NEG=>NegManipulated_ERR_EFF, 
    ERR_EFF=>EffectiveError)

Representation in ST

Representation:

PCON3_Instance (SP:=SetpointInput, PV:=ProcessVariable, 
    MODE:=OperatingModes, PARA:=Parameter, 
    YMAN_POS:=ManManipulated_Y_POS, 
    YMAN_NEG:=ManManipulated_Y_NEG, 
    Y_POS=>PosManipulated_ERR_EFF, 
    Y_NEG=>NegManipulated_ERR_EFF, 
    ERR_EFF=>EffectiveError) ;

PCON3 parameter description

Description of input parameters:

Parameter	Data type	Description
SP	REAL	Setpoint input
PV	REAL	Actual value input
MODE	Mode_MH	Operating mode
PARA	Para_PCON3	Parameter
YMAN_POS	BOOL	Manual manipulation for Y_POS
YMAN_NEG	BOOL	Manual manipulation for Y_NEG

Description of output parameters:

Parameter	Data type	Description
Y_POS	BOOL	"1" = positive manipulated variable at output ERR_EFF
Y_NEG	BOOL	"1" = negative manipulated variable at output ERR_EFF
ERR_EFF	REAL	Effective switch value

Parameter description Mode_MH

Data structure description

Element	Data type	Description
man	BOOL	"1" = Manual mode
halt	BOOL	"1" = Halt mode

Parameter description Para_PCON3

Data structure description

Element	Data type	Description
gain	REAL	Feedback gain (feedback parameter set)
lag_neg	TIME	Time constant of the quick feedback (Feedback Parameter Set)
lag_pos	TIME	Time constant of the slow feedback (Feedback Parameter Set)
hys	REAL	Hysteresis from three point switch
db	REAL	Dead zone
xf_man	REAL	Reset value of the feedback in % (0 – 100)

Runtime error

For a list of all block error codes and values, see CLC_PRO.

REAL

The REAL type is encoded in a 32 bit format.

The possible value ranges are shown in the figure below:

When a result is:

between -1,175494e-38 and 1,175494e-38, it is considered to be a DEN;
less than -3.402824e+38, the symbol -INF (for - infinity) is displayed;
greater than +3.402824e+38, the symbol INF (for + infinity) is displayed;
undefined (square root of a negative number), the symbolNAN is displayed.

NOTE: The IEC 559 standard defines two classes of NAN: the silent NAN (QNAN) and the signaling NAN (SNAN). A QNAN is a NAN with a most significant fraction bit while an SNAN is a NAN without a most significant fraction bit (bit number 22). QNANs can be propagated via most arithmetic operations without throwing an exception. As for SNANs, they generally indicate n invalid operation when they are used as operands in arithmetic operations (see %SW17 and %S18).

NOTE: When a DEN (non-standardized number) is used as an operand, the result is not significant.