Description

Function description

The function block FGEN represents a function generator. It generates a signal form at the Y output which is defined in the data structure Para_FGEN. The function block can be cascaded, i.e. if several of these EFBs are used, various signal forms can be created and laid over one another.

The following 8 different signal forms can be generated:

Jump function
Ramp function
Delta function
Saw-tooth function
Square wave function
Trapezoid function
Sine function
Random Number

NOTE: This function block performs an internal initialization in the first program cycle after a warm start or cold start (e.g. application download or power cycle) of the PLC program.

Due to this, you have to make sure that the function block is invoked in the first program cycle. In case of inkoving the function block in a later program cycle, the internal initialization will not be performed and the ouputs may deliver wrong values.

WARNING

UNEXPECTED OUTPUT BEHAVIOUR

Make sure that the function block is always invoked in the first program cycle.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

and can be configured as additional parameters.

Representation in FBD

Representation:

Representation in LD

Representation:

Representation in IL

Representation:

CAL FGEN_Instance (R:=ResetFlag, START:=StartFlag, 
    PARA:=Parameter, YOFF:=Output_Y_Offset, 
    Y=>FunctionGeneratorOutput, 
    ACTIVE=>FunctionGeneratorActiv, N=>NumberOfPeriods)

Representation in ST

Representation:

FGEN_Instance (R:=ResetFlag, START:=StartFlag, 
    PARA:=Parameter, YOFF:=Output_Y_Offset, 
    Y=>FunctionGeneratorOutput, 
    ACTIVE=>FunctionGeneratorActiv, N=>NumberOfPeriods) ;

FGEN parameter description

Description of input parameters:

Parameter	Data type	Description
R	BOOL	1: Reset
START	BOOL	1: Start function generator
PARA	Para_FGEN	Parameter
YOFF	REAL	Offset for output Y

Description of output parameters:

Parameter	Data type	Description
Y	REAL	Function generator output
ACTIVE	BOOL	ACTIVE = 1: Function generator is active
N	INT	Number of intervals since start

Parameter description Para_FGEN

Data structure description

Element	Data type	Description
func_no	INT	Generator function choice (1-8)
amplitude	REAL	Function amplitude
halfperiod	TIME	Half cycle duration
t_off	TIME	Idle time constant
t_rise	TIME	Rise time constant
t_acc	TIME	Smoothing time
unipolar	BOOL	"1 "= Signal unipolar "0 "= Signal bipolar

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.