ABS block

Short summary

Name	`ABS`
→POU type	→function
Category	IEC-block, Numeric, block with internal error diagnostic
Conform to →IEC-standard	no restrictions
Graphical interface
Available since	version 1.17.0 (for Neuron Power Engineer) – initial variant version 2.0.14 (for library `Standard`) – internal error diagnostic for block 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 Abs is called: The block returns the absolute value (i.e. without sign) of the value connected to the input value.

Special case: If the input gets a negative value that matches the lower limit of the data type, the block returns this negative value. Reason: There is no corresponding positive value for the lower limit (= the most negative value). Furthermore, the output ENO is set to value FALSE.
See under "Example for usage within ST-editor": If the most negative SINT value -128 is connected to the input, the blocks returns the value -128 (the most positive SINT value is 127) and ENO=FALSE.

Inputs, return value

	Identifier	→Data type	Description
Inputs:	`IN`	`REAL`, `LREAL`, `USINT`, `UINT`, `UDINT`, `ULINT`, `SINT`, `INT`, `DINT` or `LINT` (corresponds to →generic data type `ANY_NUM`)	value
Return value:	–	`REAL`, `LREAL`, `USINT`, `UINT`, `UDINT`, `ULINT`, `SINT`, `INT`, `DINT` or `LINT` (corresponds to →generic data type `ANY_NUM`)

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 return value. If the return value is a negative value that matches the lower limit of the data type, the output ENO of the block is set to value FALSE (or an equivalent).

Example for usage within ST-editor

PROGRAM Test

VAR

      result1, result2, result3 : SINT;

                                  CheckENO1, CheckE<NO2, CheckENO3 : BOOL;

   END_VAR

   result1 := ABS(IN := -5, ENO => CheckENO1);      (* The variable 'result1' evaluates to '5'. The variable 'CheckENO1' evaluates to 'TRUE'. *)

   result2 := ABS(IN := -127, ENO => CheckENO2);    (* The variable 'result2' evaluates to '127'. The variable 'CheckENO2' evaluates to 'TRUE'. *)

   result3 := ABS(IN := -128, ENO => CheckENO3);    (* The variable 'result3' evaluates to '-128'. The variable 'CheckENO3' evaluates to 'FALSE'. *)

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.