Short summary

Name	`UNPACK2`
→POU type	→function
Category	IEC-block, ConvertEnh
Conform to →IEC-standard	not defined in IEC-standard
Graphical interface
Available since	version 1.50.0 (for logi.CAD 3)

Functionality

The block transfers the value that is connected to the input IN bytewise to the outputs OUT0 and OUT1 . In case of target systems saving data in little →endian format, the lowest significant byte of the input is transferred to the output OUT0, the highest significant byte to OUT1. A reversed behavior is true for target systems saving data in big endian format.

Special cases (see under "Example for usage within ST-editor" ) :

If the size of the input value (number of bytes representing the data type) is > than the number of the outputs, only the lower significant input bytes are transferred.
If there are more output bytes than the input value contains, the higher significant output bytes remain not-initialized. In case of target systems saving data in little endian format, these are the outputs positioned in the lower part of the block.

In-/Outputs

	Identifier	→Data type	Description
Inputs:	`IN`	`REAL`, `LREAL`, `USINT`, `UINT`, `UDINT`, `ULINT`, `SINT`, `INT`, `DINT`, `LINT`, `TIME`, `BOOL`, `BYTE`, `WORD`, `DWORD`, `LWORD`, `DATE_AND_TIME`, `DATE` or `TIME_OF_DAY`	input value
Outputs:	`OUT0`	`BYTE`	1st byte output value
Outputs:	`OUT1`	`BYTE`	2nd byte 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 following example is valid for target systems saving data in little endian format . The calculated values are evaluated by using the Assert block .

FUNCTION_BLOCK ExampleUnpack2
  VAR
    resultA1, resultA2, resultB1, resultB2 : BYTE;
  END_VAR
  UNPACK2(IN := DWORD#16#04030201, OUT0 => resultA1, OUT1 => resultA2);
  UNPACK2(IN := WORD#16#0201, OUT0 => resultB1, OUT1 => resultB2);
 
  Assert(resultA1 = 16#01);
  Assert(resultA2 = 16#02);
  Assert(resultB1 = 16#01);
  Assert(resultB2 = 16#02);
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.