Description

Function description

The function block creates a moving average from a fixed number of input values (inputX). The output is the average of all values between the current X value and the oldest X value (N-1). Up to 50 input values can be stored (N).

The function block has both a manual and automatic mode.

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.

Formula

For RDY = 1:

Explanation of the variables

Variable	Description
Y(new)	Y Value in current program cycle
Y (old)	Y Value from the last program cycle
N	Window size (number of values in the buffer)
X(N-1)	oldest X value in the buffer

Representation in FBD

Representation:

Representation in LD

Representation:

Representation in IL

Representation:

CAL AVGMV_Instance (MAN:=Mode, X:=InputValue, 
    N:=WindowSize, YMAN:=ManualValue, Y=>Average,
    RDY=>BufferReady)

Representation in ST

Representation:

AVGMV_Instance (MAN:=Mode, X:=InputValue,
    N:=WindowSize, YMAN:=ManualValue, Y=>Average,
    RDY=>BufferReady) ;

Parameter description

Description of input parameters:

Parameter	Data type	Description
MAN	BOOL	"0" = Automatic operating mode "1" = Manual operating mode
X	REAL	Input
N	INT	Window size (number of input values that are loaded in the buffer; max. 50)
YMAN	REAL	Manual value

Description of output parameters:

Parameter	Data type	Description
Y	REAL	Average value
RDY	BOOL	"1" = n Value in buffer, i.e. buffer is ready "0" = Buffer not ready

Runtime error

An error message is returned if

N=0 or N>50

NOTE: For a list of all block error codes and values, see Measurement.

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.