FB_MemBufferSplit

This function block splits a memory area (data buffer) into several smaller segments of certain maximum length as required. The function block returns a smaller partial segment, if the length of the last segment is smaller than required.

Inputs

VAR_INPUT
    eCmd     : E_EnumCmdType := eEnumCmd_First;
    pBuffer  : POINTER TO BYTE;
    cbBuffer : UDINT;
    cbSize   : UDINT;
END_VAR

Name	Type	Description
eCmd	E_EnumCmdType	Control parameters for the function block. eEnumCmd_First returns the first segment, eEnumCmd_Next returns the next segment. No other parameters are used.
pBuffer	BYTE	Address (pointer) of the data buffer to be divided. The address can be determined with the ADR operator.
cbBuffer	UDINT	Length of the data buffer to be divided. The length can be determined with the SIZEOF operator.
cbSize	UDINT	Maximum segment size into which the data buffer is to be divided.

Outputs

VAR_OUTPUT
    bOk       : BOOL;
    pSegment  : POINTER TO BYTE;
    cbSegment : UDINT;
    bEOS      : BOOL;
END_VAR

Name	Type	Description
bOk	BOOL	TRUE = success, FALSE = error, invalid parameter value or no further segment available.
pSegment	BYTE	Address (pointer) to the next data segment.
cbSegment	UDINT	Length (bytes) of the next data segment.
bEOS	BOOL	End of segment. TRUE = last segment. FALSE = further segments follow.

Example:

In the following example the buffer variable is divided into 5-byte segments. The returned segments are converted to a hexadecimal string for test purposes.

PROGRAM MAIN
VAR
    bSplit   : BOOL := TRUE;
    buffer   : ARRAY[1..30] OF BYTE := [16#A,1,2,3,4,5,6,7,8,9,16#B,1,2,3,4,5,6,7,8,9,16#C,1,2,3,4,5,6,7,8,9];
    fbSplit  : FB_MemBufferSplit;
    sHex     : T_MaxString;
END_VAR

IF bSplit THEN
    bSplit := FALSE;
    fbSplit.eCmd := eEnumCmd_First;

    REPEAT
        fbSplit( pBuffer := ADR(buffer), cbBuffer := SIZEOF(buffer), cbSize := 5 );
        IF fbSplit.bOk THEN
            sHex := DATA_TO_HEXSTR( pData := fbSplit.pSegment, cbData := fbSplit.cbSegment, FALSE );
            fbSplit.eCmd := eEnumCmd_Next;
        END_IF
    UNTIL NOT fbSplit.bOk
    END_REPEAT
END_IF

Requirements

Development environment	Target platform	PLC libraries to be integrated (category group)
TwinCAT v3.1.0	PC or CX (x86, x64, ARM)	Tc2_Utilities (System)