FB_DBRecordSelect

VAR_INPUT

VAR_INPUT
    sNetID      : T_AmsNetID;
    hDBID       : UDINT;
    sSelectCmd  : T_MaxString;
    nRecordIndex: UDINT;
    cbRecordSize: UDINT;
    pDestAddr   : DWORD;
    bExecute    : BOOL;
    tTimeout    : TIME;
END_VAR 

sNetID: String containing the AMS network ID of the target device, at which the ADS command is directed.

hDBID: Indicates the ID of the database to be used.

sSelectCmd: Indicates which SELECT command is to be executed.

nRecordIndex: Gives the index of the data record that is to be read.

cbRecordSize: Provides the size of a data record in bytes.

pDestAddr: Indicates the address of the structure to which the record is to be written.

bExecute: The command is executed with a rising edge.

tTimeout: Indicates the time before the function is cancelled.

VAR_OUTPUT

VAR_OUTPUT
    bBusy    : BOOL;
    bError   : BOOL;
    nErrID   : UDINT;
    sSQLState: ST_DBSQLError;
    nRecords : UDINT;
END_VAR 

bBusy: The command is in the process of being transmitted by ADS. No new command will be accepted as long as bBusy remains TRUE.

bError: Becomes TRUE, as soon as an error occurs.

nErrID: Returns the ADS error code or TcDatabaseSrv_Error_Codes if the bError output is set.

sSQLState: Returns the SQL error code of the corresponding database type

nRecords: Returns the number of data records.

Example in ST:

Since the table, from which the records are to be read, has the structure below, a PLC structure with a similar structure must be created.

Table:

Structure:

TYPE ST_Record :
STRUCT
    ID       : T_ULARGE_INTEGER;
    Timestamp: DT;
    Name     : STRING;
    VALUE    : LREAL;
END_STRUCT
END_TYPE 

The library TcUtilities.lib must be integrated in order to be able to use the data type T_ULARGE_INTEGER.

For ARM processors the data types have to be arranged differently due to the byte alignment, and a "dummy BYTE" has to be added.

TYPE ST_Record :
STRUCT
    ID       : T_ULARGE_INTEGER;
    Timestamp: DT;
    Value    : LREAL;
    Name     : STRING;
    Dummy    : BYTE;
END_STRUCT
END_TYPE 

PROGRAM MAIN
VAR
    FB_DBRecordSelect1: FB_DBRecordSelect;
    cmd               : T_Maxstring := 'SELECT * FROM myTable';
    (* Unter ARM*) 
    (*cmd             : T_Maxstring := 'SELECT ID,Timestamp,Value,Name FROM myTable'*)
    (*----------*)
    record            : ST_Record;
    busy              : BOOL;
    err               : BOOL;
    errid             : UDINT;
    recAnz            : DINT;
END_VAR 

PLC program

FB_DBRecordSelect1(
    sNetID      := ,
    hDBID       := 2,
    sSelectCmd  := cmd,
    nRecordIndex:= 0,
    cbRecordSize:= SIZEOF(record),
    pDestAddr   := ADR(record),
    bExecute    := TRUE,
    tTimeout    := T#15s,
    bBusy       => busy,
    bError      => err,
    nErrID      => errid,
    nRecords    => recAnz);

Requirements