FB_DBRead

FB_DBRead 1:

The FB_DBRead function block allows values to be read from a database. The function block searches for the specified sDBVarName in the "Name" column of the database table and then outputs the corresponding value from the "Value" column. If the searched sDBVarName exists several times in the database table, the first record found is output.

VAR_INPUT

VAR_INPUT
    sNetID    : T_AmsNetId;
    hDBID     : DINT;
    sDBVarName: STRING(80);
    cbReadLen : UDINT;
    pDestAddr : POINTER TO BYTE;
    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.

sDBVarName: Gives the name of the variable that is to be read.

cbReadLen: Indicates the length of the buffer that is to be read.

pDestAddr: Contains the address of the buffer which is to receive the data that has been read.

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;
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

Requirements

Development environment	Target platform	PLC libraries to be linked
TwinCAT v3.0.0	PC or CX (x86)	Tc2_Database