Short summary

Name	`FORCEMRK`
→POU type	→function block
Category	IEC-block, SelectEnh
Conform to →IEC-standard	not defined in IEC-standard
Graphical interface
Available since	version 1.52.0 (for logi.CAD 3) – initial variant version 2.0.11 (for library `Standard`) – additional data types for `IN` and `OUT` (`STRING`, `CHAR`, user-defined data types; `FVAL` und `FSW` provided as local, retentive variables (instead of inputs) Variables of `FORCEMRK` instances can be displayed e.g. in the Values of Variables view only, if the target system uses a communication via →Gateway.

Functionality

The block makes a selection to change the returned output value (to →force a value).

If the local, →retentive variable FSW (= the force switch) is set to value FALSE (or an equivalent), the block returns the value of input IN. If the local, retentive variable FSW (= the force switch) is set to value TRUE (or an equivalent), the block returns the value of the local, retentive variable FVAL.

Special case: If a STRING value is connected to the input , logi.CAD 3 uses the fixed length of 128 for the input and the output. However, if the connected STRING value is longer, the output ENO of the embracing →POU is set to value FALSE (or an equivalent).

Restrictions

The following restrictions apply to the usage of overloadable function block instances:

The declaration is limited to local variables.
The usage as array base type is not allowed.
The usage as structure element is not allowed.
Instance data can be displayed or changed only, if the target system uses a communication via →Gateway. The instance data are displayed e.g. within the Values of Variables view or within →OLT-fields.

Good to know

Use an →OLT-field for a force marker inserted within the FBD-editor in order to toggle the force marker between the value of the input and the force value. Details: See "Creating or editing OLT-fields in FBD".

Use the Force Markers view in order to enter force values for several force markers from within a central point of logi.CAD 3 and to activate their force switch in one go. Details: See "Writing a force value for force marker onto the PLC".

In-/outputs

	Identifier	→Data type	Description
Inputs:	`IN`	`REAL`, `LREAL`, `USINT`, `UINT`, `UDINT`, `ULINT`, `SINT`, `INT`, `DINT`, `LINT`, `TIME`, `BOOL`, `BYTE`, `WORD`, `DWORD`, `LWORD`, `STRING`, `CHAR`, `DATE_AND_TIME`, `DATE` or `TIME_OF_DAY` or a →user-defined data type Restriction: In case of →array data types, only one-dimensional arrays are allowed.	input value
Outputs:	`OUT`	`REAL`, `LREAL`, `USINT`, `UINT`, `UDINT`, `ULINT`, `SINT`, `INT`, `DINT`, `LINT`, `TIME`, `BOOL`, `BYTE`, `WORD`, `DWORD`, `LWORD`, `STRING`, `CHAR`, `DATE_AND_TIME`, `DATE` or `TIME_OF_DAY` or a →user-defined data type Restriction: In case of →array data types, only one-dimensional arrays are allowed.	output value

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

See:

"Blocks for safe logic" whether this block is supported for developing safety-relevant applications.
"Highlighting safe logic in the FBD-editor" for the effects when using the block as a block for safe logic .

Example for usage within ST-editor

The calculated values are evaluated by using the Assert block .

FUNCTION_BLOCK ExampleForceMrk
    VAR
        iForceMrk1 : FORCEMRK;
        OUT1 : INT;
    END_VAR
       
    iForceMrk1(IN := 3, OUT => OUT1);
    Assert(OUT1 = 3);       
END_FUNCTION_BLOCK

When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.