SUM_W: Summer

Function description

The function performs the weighted summation of 3 numerical input variables according to the underlying formula.

and can be configured as additional parameters.

Formula

The function SUM_W operates as follows:

Representation in FBD

Representation:

Representation in LD

Representation:

Representation in IL

Representation:

LD InputValue1
SUM_W InputValue2, InputValue3, Parameters
ST Result

Representation in ST

Representation:

Result := SUM_W (InputValue1, InputValue2, InputValue3,
                 Parameters);

Parameter description SUM_W

Description of input parameters:

Parameter	Data type	Description
InputValue1 bis InputValue3	REAL	Numerical variables to be processed
Parameters	Para_SUM_W	Parameter

Description of output parameters:

Parameter	Data type	Description
Result	REAL	Result of the calculation

Parameter description Para_SUM_W

Data structure description

Element	Data type	Description
k1 to k3, c1	REAL	Calculation coefficients

Runtime error

An runtime error appears if a non floating point value is recorded or if there is a problem with a floating point calculation. The output Result will not be altered.

NOTE: For a list of all the block error messages and values, see Common Floating Point Errors.

EN stands for ENable; it is an optional block input. When the EN input is enabled, an ENO output is set automatically.

If EN = 0, the block is not enabled; its internal program is not executed, and ENO is set to 0.

If EN = 1, the block's internal program is run and ENO is set to 1. If an error occurs, ENO is set to 0.

If the EN input is not connected, it is set automatically to 1.

ENO

ENO stands for Error NOtification; this is the output associated with the optional input EN.

If ENO is set to 0 (because EN = 0 or in case of an execution error):

the status of the function block outputs remains the same as it was during the previous scanning cycle that executed correctly;
the output(s) of the function, as well as the procedures, are set to "0".

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.