WRITE_INPUT_REAL: Writing Inputs of Type REAL

Function Description

WRITE_INPUT_REAL is used to simulate (write) a value at a variable, IODDT variable, or state RAM. The input is written directly when WRITE_INPUT_REAL is invoked.

The function block can be used with a real PLC and the PLC simulator.

Restrictions

The function block provides access to one variable at a time (elementary data types and not arrays of elementary data types).
The simulation block WRITE_INPUT_REAL does not work if the I/O module is configured in a RIO drop but works properly if the I/O module is configured in a local rack or DIO device.

NOTE: Using the WRITE_INPUT_REAL EFB with RIO networks, the behavior in simulation mode could be different from PLC behavior. The input is set by the WRITE_INPUT_REAL EFB but overwritten by the value sent by the RIO scanner in the OUT phase of the PLC scan.

The additional parameters and can be configured.

FBD representation

Representation:

LD representation

Representation:

IL representation

Representation:

WRITE_INPUT_REAL (INP:=Value (*Real*)) 
ST Simulated_Input (*Real*)

ST representation

Representation:

(*Real*) Simulated_Input:=WRITE_INPUT_REAL (INP:=Value (*Real*));

Parameter Description

The following table describes the input parameters:

Parameter	Type	Comment
INP	REAL	value to be assigned to the variable

The following table describes the output parameters:

Parameter	Type	Comment
OUTP	REAL	variable to be modified

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.