Description

Function description

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

and can be configured as additional parameters.

Properties

The function block has 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 PCON2_Instance (SP:=SetpointInput, PV:=ProcessVariable, 
    MODE:=OperatingModes, PARA:=Parameter, 
    YMAN:=ManualManipulated_ERR_EFF, 
    Y=>ManipulatedOutput, ERR_EFF=>EffectiveError)

Representation in ST

Representation:

PCON2_Instance (SP:=SetpointInput, PV:=ProcessVariable, 
    MODE:=OperatingModes, PARA:=Parameter, 
    YMAN:=ManualManipulated_ERR_EFF, 
    Y=>ManipulatedOutput, ERR_EFF=>EffectiveError) ;

PCON2 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_PCON2	Parameter
YMAN	BOOL	"1" = Manual value for ERR_EFF

Description of output parameters:

Parameter	Data type	Description
Y	BOOL	"1" = Output manipulated variable
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_PCON2

Data structure description

Element	Data type	Description
gain	REAL	Feedback boost
lag_neg	TIME	Time constants of the quick feedback
lag_pos	TIME	Time constants of the slow feedback
hys	REAL	Hysteresis from two point switch
xf_man	REAL	Reset value of the feedback in % (0 – 100)

Runtime error

In the following cases a warning is given:

Causes	Behavior of the controller
lag_neg = 0 and lag_pos > 0	The controller works as if it had only a negative feedback with time constant lag_pos.
lag_pos < lag_neg > 0	The controller works as if it had only a negative feedback with time constant lag_neg.
xf_man < 0 or xf_man > 100	The controller works without internal feedback paths.

NOTE: 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.