ReadAsString

This method reads a specified number of records from the result data cached in the TwinCAT Database Server. An array of strings is specified into which this data is to be copied as JSON.

Syntax

METHOD ReadAsString : BOOL
VAR_INPUT
    nStartIndex: UDINT := 0;
    nRecordCount: UDINT := 1;
    pData: POINTER TO BYTE;
    cbData: UDINT;
    nMaxDocumentSize : UDINT; 
    bDataRelease: BOOL := TRUE;
END_VAR

Inputs

Name	Type	Description
nStartIndex	UDINT	Indicates the index of the first record to be read.
nRecordCount	UDINT	Indicates the number of records to be read.
pData	POINTER TO BYTE	Indicates the address of the string array into which the records are to be written.
cbData	UDINT	Indicates the size of the string array in bytes.
nMaxDocumentSize	UDINT	Indicates the maximum size of a single JSON document from pData.
bDataRelease	BOOL	Releases the cached data.

Return value

Name	Type	Description
ReadAsString	BOOL	Displays the status of the method. Returns TRUE as soon as the method execution is finished, even in the event of an error.

Sample:

VAR
    fbNoSqlResult : FB_NoSQLResultEvt(sNetID := '', tTimeout := T#5S);
    aRead_Json : ARRAY[0..2] OF STRING(1000);
    TcMessage : I_TcMessage;
END_VAR

IF fbNoSqlResult.ReadAsString(
    nStartIndex:= 0, 
    nRecordCount:= 3, 
    pData:= ADR(aRead_Json), 
    cbData:= SIZEOF(aRead_Json), 
    MaxDocumentSize:= SIZEOF(aRead_Json[0]), 
    bDataRelease:= TRUE)
THEN
    IF fbNoSqlResult.bError THEN
        TcMessage := fbNoSqlResult.ipTcResult;
        nstate := 255; 
    ELSE
        nstate := nstate+1;
    END_IF    
END_IF