BOOL_TO_STRING

BOOL into STRING

The function BOOL_TO_STRING converts a value of the data type BOOL into a value of the data type STRING[2]. The resulting string is represented by ' 0' or ' 1'.

Parameters

Input

Unnamed input (BOOL): Input data type

Output

Unnamed output (STRING): Conversion result

Remarks

When using the data type STRING with small PLCs like FP-e or FP0, make sure that the length of the result string is equal to or greater than the length of the source string.

Example result string = '0' or '1'

POU header

All input and output variables used for programming this function have been declared in the POU header. The same POU header is used for all programming languages.

	VAR
		input_value: BOOL:=FALSE;
		result_string: STRING;
	END_VAR

The input variable input_value of the data type BOOL is intialized by the value TRUE. The output variable result_string is of the data type STRING[2]. It can store a maximum of two characters. You can declare a character string that has more than one character, e.g. STRING[5]. From the 5 characters reserved, only 2 are used.

Instead of using the variable input_value, you can write the constants TRUE or FALSE directly to the function’s input contact in the body.

POU body

The input_value of the data type BOOL is converted into STRING[2]. The converted value is written to result_string. When the variable input_value = TRUE, result_string shows ' 1'.

LD body

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 5 ;
        NETWORK_BODY
B(B_F,BOOL_TO_STRING!,Instance,9,1,19,3,,?D?C);
B(B_VARIN,,input_value,7,1,9,3,);
B(B_VAROUT,,result_string,19,1,21,3,);
L(1,0,1,5);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

ST body

IF Boolean_value then
    output_value:=BOOL_TO_STRING(input_value);
END_IF;

IL body

Example result string = 'TRUE' or 'FALSE'

POU header

If you wish to have the result 'TRUE' or 'FALSE' instead of ' 0' or ' 1', you cannot use the function BOOL_TO_STRING. This example illustrates how you create a STRING[5] that contains the characters 'TRUE' or 'FALSE' from an input value of the data type BOOL.All input and output variables used for programming this function have been declared in the POU header.The same POU header is used for all programming languages.

	VAR
		input_value: BOOL:=TRUE;
			(*example value*)
		result_string: STRING[5]:='';
			(*result: here TRUE*)
		@'': @'';
		@'': @'';
	END_VAR

In this example, both an input variable input_value of the data type BOOL and an output variable result_string of the data type STRING[5] are declared.

POU body

In order to realize the intended operation, the standard function MOVE is used. It assigns the value of its input to its output unchanged. At the input, the STRING constant 'TRUE' or 'FALSE' is attached. In essence a "BOOL to STRING" conversion occurs, since the Boolian variable input_variable at the enable input (EN) contact decides the output of STRING.

LD body

BODY
    WOKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORRKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 8 ;
        NETWORK_BODY
B(B_CONTACT,,input_value,3,1,5,3,);
B(B_F,E_MOVE!,Instanz,11,0,17,4,,?DEN?D?AENO?C);
B(B_VARIN,,'TRUE',9,2,11,4,);
B(B_VAROUT,,result_string,17,2,19,4,);
B(B_F,E_MOVE!,Instanz,11,4,17,8,N,?DEN?D?AENO?C);
B(B_VARIN,,'FALSE',9,6,11,8,);
B(B_VAROUT,,result_string,17,6,19,8,);
L(1,2,3,2);
L(5,2,11,2);
L(1,0,1,8);
L(6,2,6,6);
L(6,6,11,6);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY