PACK block

Short summary

Name	`PACK`
→POU type	→function
Category	Standard (non-safe), ConvertEnh
Conform to →IEC-standard	not defined in IEC-standard
Graphical interface
Available since	version 1.50.0 (for Neuron Power Engineer) – initial variant version 3.2.5 (for library `Standard`) – corrected functionality for platforms created by a system integrator version 3.8.0 (for library `Standard`) – changed behavior when the return value is connected to an input of a generic data type version 3.8.0 (for library `Standard (non-safe)`): block moved in this library

Functionality

The block returns the transferred values of the bytes connected to the inputs IN0 – IN7. In case of target systems saving data in little →endian format, the byte of input IN0 is transferred to the lowest significant byte of the return value, the byte of input IN7 to the highest significant byte of the return value. 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 result data type (number of bytes representing the data type) is > than the number of the connected input bytes, the higher significant bytes of the return value remain not-initialized.
In case of BOOL values for the return value, TRUE is returned for each value ≠ 0 at input IN0.
If more input bytes are connected than the result data type can hold, only the lower significant input bytes are transferred to the return value. In case of target systems saving data in little endian format, these are the inputs positioned in the upper part of the block.

The block reports an error whenthe output is connected to a block input of a generic data type (e.g. the input of a TO_INT block). This behavior is caused due to the statement anyOutputMustBeConcreteResolved in the interface of the PACK block. See under "Properties for implementing vendor blocks" for details on this statement. To fix such an error, you might want to declare an auxiliary variable and assign the calls to this auxiliary variable (see under "Typing of expressions" for details on this workaround for a nested usage of PACK together with other blocks).

Inputs, return value

	Identifier	→Data type	Description
Inputs:	`IN0`	`BYTE`	1st value
	`IN1`	`BYTE`	2nd value
	... (extensible until)
	`IN7`	`BYTE`	8th value
Return value:	`–`	`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 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 ExamplePack

VAR

    result1, result2 : DWORD;

    result2a : WORD;

  END_VAR

  result1 := PACK(IN0 := 16#01, IN1 := 16#02);                                  (* DWORD = 4 bytes *)

  result2 := PACK(IN0 := 16#01, IN1 := 16#02, IN2 := 16#04, IN3 := 16#07);

  result2a := PACK(IN0 := 16#01, IN1 := 16#02, IN2 := 16#03, IN3 := 16#04);     (* WORD = 2 bytes *)

  Assert(result1 = 16#0201);       (* '16#0201' equals to '513' (decimal). *)

  Assert(result2 = 16#07040201);   (* '16#07040201' equals '117_703_169' (decimal). *)

  Assert(result2a = 16#0201);      (* '16#0201' equals '513' (decimal). *)

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.