Read
This method reads a specified number of records from the result data cached in the TwinCAT Database Server.
Syntax
METHOD Read : BOOL
VAR_INPUT
nStartIndex: UDINT := 0;
nRecordCount: UDINT := 1;
pData: POINTER TO BYTE;
cbData: UDINT;
bWithVerifying: BOOL := FALSE;
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 | Address of the structure array into which the records are to be written. |
cbData | UDINT | Indicates the size of the structure array in bytes. |
bWithVerifying | BOOL | Return data are compared with the pData structure array and adjusted if necessary. |
bDataRelease | BOOL | Releases the cached data. |
Return value
Name | Type | Description |
|---|---|---|
Read | 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
fbSqlResult : FB_SQLResultEvt(sNetID:='', tTimeout := T#5S);
aReadStruct : ARRAY[1..5] OF ST_StandardRecord;
END_VAR
// get values from internal tc db srv storage
IF fbSqlResult.Read(2, 3, ADR(aReadStruct), SIZEOF(aReadStruct), FALSE, TRUE) THEN
IF fbSqlResult.bError THEN
nState := 255;
ELSE
nState := nState+1;
END_IF
END_IF
Result in the PLC:
