Description

Function description

With this function block an input signal is delayed by a time, the so-called deadtime.

The function block delays the signal X by the deadtime T_DELAY before it appears again at Y.

The function block utilizes a 128 element delay buffer to hold a sequence of X values, i.e. during the T_DELAY time 128 discrete X values are detained. The buffer is used in such a way that it corresponds with the operating mode.

Whether the system is started cold or warm, the value of Y remains unchanged. The internal values are set to the value of X.

After a change of deadtime T_DELAY or a cold or warm system start, the output READY goes to "0". This means: that the buffer is empty and not ready.

The function block has the following operating mode:

Manual mode
Halt
Automatic.

and can be configured as additional parameters.

NOTE: The delay time continues to run even if the block is disabled via the EN parameter, because the block calculates its time differences according to the system clock.

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.

Formula

The transfer function is:

Representation in FBD

Representation:

Representation in LD

Representation:

Representation in IL

Representation:

CAL DEADTIME_Instance (X:=InputValue, MODE:=OperatingModes, 
    T_DELAY:=DeadTime, YMAN:=ManualManipulatedValue, 
    Y=>Output, READY=>InternalBufferFlag)

Representation in ST

Representation:

DEADTIME_Instance (X:=InputValue, MODE:=OperatingModes, 
    T_DELAY:=DeadTime, YMAN:=ManualManipulatedValue, 
    Y=>Output, READY=>InternalBufferFlag) ;

DEADTIME parameter description

Description of input parameters:

Parameter	Data type	Description
X	REAL	Input value
MODE	Mode_MH	Operating mode
T_DELAY	TIME	Deadtime
YMAN	REAL	Manually manipulated value

Description of output parameters:

Parameter	Data type	Description
Y	REAL	Output
READY	BOOL	"1" = internal buffer is full "0" = internal buffer is not full (e.g. after warm/cold start or modification of deadtime)

Parameter description Mode_MH

Data structure description

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

Runtime error

An error message is returned when an invalid floating point number lies at input YMAN or X.

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.