PLC_ReadSymInfoByName

VAR_INPUT

VAR_INPUT
    NETID    : T_AmsNetId;
    PORT     : T_AmsPort;
    SYMNAME  : T_MaxString;
    START    : BOOL;
    TMOUT    : TIME := DEFAULT_ADS_TIMEOUT;
END_VAR

NETID: The AmsNetId of the TwinCAT computer on which the function is to be executed can be entered here (type: T_AmsNetID). If it is to be run on the local computer, an empty string can be entered.

PORT: The port number of the PLC run-time system to which the symbolic variable belongs (type: T_AmsPort).

SYMNAME: The symbol name of the PLC variable whose information is to be read (type: T_MaxString, max. 255 characters, including the whole path, e.g. 'MAIN.INIT_TASK.VARINT' ).

START: the block is activated by a positive edge at this input.

TMOUT: States the length of the timeout that may not be exceeded by execution of the ADS command.

VAR_OUTPUT

VAR_OUTPUT
    BUSY     : BOOL;
    ERR      : BOOL;
    ERRID    : UDINT;
    SymInfo  : SYMINFOSTRUCT;
END_VAR

BUSY: When the function block is activated this output is set. It remains set until a feedback is received.

ERR: If an error should occur during the transfer of the command, then this output is set once the BUSY output was reset.

ERRID: Supplies the ADS error number when the ERR output is set.

SymInfo: A structure with additional information on the symbolic variable (type: SYMINFOSTRUCT).

Example:

PROGRAM MAIN
VAR
    PLC_ReadSymInfoByName1  : PLC_ReadSymInfoByName;
    bStart AT%QX0.5         : BOOL; (*Starts FB execution*)
    bBusy                   : BOOL;
    bError                  : BOOL;
    iErrorId                : UDINT;
    SymInfo                 : SYMINFOSTRUCT;(*Structure with sombol information*)
END_VAR

Online View:

The data obtained in this way has the following meanings:

symEntryLen = 16#43: The actual length of the entry in the symbol table is 67 bytes;

idxGroup = 16#F031: It is a variable from the PLC process image of the physical outputs;

idxOffset = 16#5: The variable is located at byte offset zero and bit offset 5;

byteSize = 16#1: The variable's value occupies one byte in memory;

adsDataType = ADST_BIT: The ADS data type ID;

symDataType = BOOL: The data type identification in the PLC;

symComment = 'STARTS FB EXECUTION': Comment that the user has added to the variable definition line.

Requirements