TRUNC block

Short summary

Name	`TRUNC`
→POU type	→function
Category	IEC-block, ConvertEnh
Conform to →IEC-standard	not defined in IEC-standard
Graphical interface
Available since	version 1.27.0 (for Neuron Power Engineer) version 3.1.0 (for library `Standard`) – For inputs of data type `REAL`, the optimized `float` variant of the C-runtime is used. Compared to previous versions, it is possible that (marginal) other results are returned within the threshold range of the block.

Functionality

The mathematical function trunc is called:

The decimal portion of the floating-point number connected to input IN is truncated (there is no rounding). The block returns the integer value as a REAL or LREAL value.

The non-overlapping value range is not considered to be an error. The return value of the block depends on the compiler and target system (see "Effects of the compiler settings on the execution" for details).

Compare: TRUNC blocks according to IEC-standard (listed under "Convert").

Inputs, return value

	Identifier	→Data type	Description
Inputs:	`IN`	`REAL`, `LREAL` (corresponds to →generic data type `ANY_REAL`)	value to truncate
Return value:	–	`REAL`, `LREAL` (corresponds to →generic data type `ANY_REAL`)

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

PROGRAM Test

VAR

      result1, result2, result3, result4, result5, result6, result7, result8 : REAL;

   END_VAR

   result1 := TRUNC(2.8);     (* The variable 'result1' evaluates to '2.0'. *)

   result2 := TRUNC(2.5);     (* The variable 'result2' evaluates to '2.0'. *)

   result3 := TRUNC(2.01);    (* The variable 'result3' evaluates to '2.0'. *)

   result4 := TRUNC(2.0);     (* The variable 'result4' evaluates to '2.0'. *)

   result5 := TRUNC(-2.0);    (* The variable 'result5' evaluates to '-2.0'. *)

   result6 := TRUNC(-2.3);    (* The variable 'result6' evaluates to '-2.0'. *)

   result7 := TRUNC(-2.5);    (* The variable 'result7' evaluates to '-2.0'. *)

   result8 := TRUNC(-2.99);   (* The variable 'result8' evaluates to '-2.0'. *)

END_PROGRAM

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.