FB_DBRead
The FB_DBRead allows values to be read from a database.
The function block searches the database table in the "Name" column for the specified sDBVarName and then outputs the corresponding value from the "Value" column. If the sDBVarName searched for is present several times in the database table, the first data record found is output.
VAR_INPUT
VAR_INPUT
sNetID : T_AmsNetId;
hDBID : DINT;
sDBVarName : STRING(80);
cbReadLen : UDINT;
pDestAddr : DWORD;
bExecute : BOOL;
tTimeout : TIME;
END_VAR
sNetID : Is a string containing the AMS network identifier of the target device to 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 the rising edge.
tTimeout : States 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 : Supplies the ADS Error Code or the TcDatabaseSrv_Error_Codes when the bError output is set.
sSQLState : Supplies the SQL error code of the specified database type.
Requirements
Development environment | Target system type | PLC libraries to be linked |
|---|---|---|
TwinCAT v2.10.0 | PC or CX (x86) | TcDatabase.Lib |
TwinCAT v2.10.0 | CX (ARM) |