Short summary

Functionality

The blocks serves for explicitly converting the value connected to input IN into a value of data type LWORD.

If the connected value is within the range of values overlapping for the data type of the input and for the result value LWORD, the blocks returns this value.

Observe as well:

• A value of the data type REAL or LREAL in the range from 0 to the maximum value of ULINT (i.e., 18_446_744_073_709_551_615) is rounded to a ULINT value. Only then the binary transfer of this value to the target data type takes place. The following behavior applies to this (according to the IEC standard):
  

  • If the source data type is smaller than the target data type, the source value is stored in the rightmost bytes of the target variable and the leftmost bytes are set to zero (= fill up with 0).

  • If the source data type is bigger than the target data type, only the rightmost bytes of the source variable are stored in the target data type.

• If a negative value of data type REAL or LREAL is connected to the input, the blocks returns the value 0. If a negative value of a different data type is connected, the block returns a value according to the data type of the return value.

• If a REAL value with more than 6 digits before the decimal point is converted, the result might be inexact. Example: For REAL#4_294_967_290.0, the block returns the value 0. The reason is the number of significant digits of REAL (details: see "Supported data types (in ST) " the note 3 and the note 4 after the table).

• If a LREAL value with more than 15 digits is converted, the result might be undefined. Example: For LREAL#9223372036854775807.0, the block returns the value -9223372036854775808. The reason is the number of significant digits of LREAL (details: see "Supported data types (in ST)" the note 3 and the note 4 after the table).
  

• The following applies to the conversion of DINT, INT and SINT: These data types are not filled up with 0 during the conversion, but they are filled up with bits (0 or 1) depending on the sign. Example : TO_LWORD(SINT#-1) has the result 16#FFFFFFFFFFFFFFFF in logi.CAD 3 instead of the result 16#0000000000000FF (as expected according to the IEC-standard).

• If converting data types to the TIME data type and vice versa, the conversion is always based on seconds.

• If a value of data type STRING is connected to the input, the value is converted to a decimal value (base: 10, allowed digits: 0 to 9) and then this decimal value is converted to a value according to the target data type . The following special cases might occur (see under "Example for usage within ST-editor" ) :

  • If the value starts with the character + , with blanks or tabs (= so-called whitespace) and the value is within the range of values for the target data type, the value is converted to a positive decimal value (without these characters). In this case, the output ENO is set to value TRUE .
    Details on this conversion: The character + as prefix for the value is ignored, blanks and tabs (= so-called whitespace) are ignored as well.

  • If the value starts with the character – and the value is within the range of values for the target data type, the value is converted analogously to a connected, negative INT value. In this case, the output ENO is set to value TRUE as well.
    Details on this conversion: The upper limit of the target data type is converted to the positive decimal value, this decimal value is increased by the value 1 and then the STRING value (in fact the corresponding decimal value) is subtracted. The result is converted to a value appropriate to the target data type.

  • If the value contains an invalid character, the block returns the value 0. In this case, the output ENO is set to value FALSE .
    

    Valid characters	invalid characters
    digits (base: 10, numbers: 0 to 9) Example for value with valid character: '7'	other characters such as letters Example for value with invalid character: '12a3', 'a123'
    one character + or – as a prefix of the value Example for value with valid character: +2 or –3	repetitions of + or – at the beginning of the value, the character + or – within the value Example for value with invalid character: '++1', '1–3'
    single underscore characters _ within the value Example for value with valid character: 1_2 or 1_2_3	underscore character _ at the beginning or the end of the value, several characters _ behind one another Example for value with invalid character: _12, 12_ or 1__2

  • If the STRING value to be converted exceeds the upper limit of the target data type, the block returns the upper limit of the target data type. In this case, the output ENO is set to value FALSE as well.

• If a value of data type CHAR is connected to the input, the conversion is analogous to a STRING value. But different to the STRING conversion, the CHAR conversion supports single digits digits 0 to 9 only. For all other characters (letters, the characters +, - and _), the block returns the value 0 and the output ENO is set to value FALSE .

Inputs, return 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 .

Internal error diagnostic for block

The block checks the value connected to the input. The output ENO of the block is set to value FALSE (or an equivalent) in the following cases:

• A STRING value contains an invalid character. (Moreover for this case, the block returns the value 0.)

• A STRING value exceeds the upper limit of the target data type. (Moreover for this case, the block returns the upper limit of the target data type.)

• The CHAR value is an invalid character. (Moreover for this case, the block returns the value 0.)

Example for usage within ST-editor

The calculated values are evaluated by using the Assert 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.