Extract the first 14 bytes of a any pointer

Dear Forum Members,

I receive data in a buffer DB with AG_LRECV.

The first 14 bytes of the buffer DB are the header of the received message. I defined an UDT for the header:

TYPE UDT_HEADER
STRUCT
    MSG_ID : INT := 0;
    MSG_LEN : INT := 0;
    MSG_COUNTER : INT := 0;
    MSG_DT DATE_AND_TIME;
END_STRUCT;
END_TYPE

DATA_BLOCK DB15
STRUCT
    MOUVEMENT : UDT_HEADER;
    DATA: ARRAY[1..100] OF BYTE;   
END_STRUCT
BEGIN
END_DATA_BLOCK

Here is the code for the receiving of the message:

 AG_LRECV(ID := t_ID // IN: INT
     ,LADDR := t_LADDR // IN: WORD
      ,RECV := i_BufferRecv  // IN: ANY
      ,NDR := o_RcvNdr // OUT: BOOL
      ,ERROR := s_RcvErr // OUT: BOOL
      ,STATUS := s_RcvStatErr  // OUT: WORD
      ,LEN := s_RcvLen
 ); // VOID

I need to get the ID Message of the header in the SCL source.

How can I get this field from the i_BufferRecv argument ?

Thanks,

Best regards,

Etienne
 

Hi, 

You need to set up an ANY pointer.  Almost the same question discussed here:

AG_LSEND and Anypointer problem in SCL

If you need any further help please come back!

I hope I could help!

Hello,

thank you for replying.

FUNCTION_BLOCK FB10
VAR_INPUT

    i_RcvBuffer : ANY;    
    V_t_RcvBuffer AT i_RcvBuffer :
    STRUCT                      // View of any header pointer
        ID: BYTE;               //
        TYP: BYTE;              //
        LENGTH: INT;            //
        DBN: INT;               //
        MemoryArea : BYTE;      // Specified memory area
        ByteAddressMSB : BYTE;  // Byte address most significant bits
        ByteAddressLSB : WORD;  // Byte address least significant bits
    END_STRUCT;
    
END_VAR

VAR_TEMP

    t_LADDR : WORD;
    t_ID : INT;
    t_RetVal : INT;
    t_Header : "UDT_HEADER";
    
    t_Any_Header                : ANY;      //temporary pointer to header area
    V_t_Any_Header AT t_Any_Header :
    STRUCT                      // View of any header pointer
        ID: BYTE;               //
        TYP: BYTE;              //
        LENGTH: INT;            //
        DBN: INT;              //
        MemoryArea : BYTE;      // Specified memory area
        ByteAddressMSB : BYTE;  // Byte address most significant bits
        ByteAddressLSB : WORD;  // Byte address least significant bits
    END_STRUCT;

END_VAR

CONST
    SIZE_HEADER := 14;
END_CONST

BEGIN
        // Receiving
    AG_LRECV(ID := t_ID // IN: INT
            ,LADDR := t_LADDR // IN: WORD
            ,RECV := i_RcvBuffer  // IN: ANY
            ,NDR := o_RcvNdr // OUT: BOOL
            ,ERROR := s_RcvErr // OUT: BOOL
            ,STATUS := s_RcvStatErr  // OUT: WORD
            ,LEN := s_RcvLen
            ); // VOID

    // Extract the header
    V_t_Any_Header := V_t_RcvBuffer;
    V_t_Any_Header.LENGTH := SIZE_HEADER;
    
    t_RetVal := BLKMOV(SRCBLK := t_Any_Header // IN: ANY
        ,DSTBLK := t_Header // OUT: ANY
        ); // INT

    // Read the message ID
    IF (t_Header.MSG_ID > 0) THEN
    // [..]
    END_IF

END_FUNCTION_BLOCK

Thanks,

Best regards,

Etienne

Hi, 

Set up the ANY pointer properly. The way I see it you need to have an any pointer for the block "AG_LRECV" and an other two for BLKMOV.   

About how to set up ANY pointer read this thread:

BLKMOV in SCL

I hope I could help!

Hi MicroMan,

thank you for replying.

You mean I shouldn't copy the any pointer V_t_RcvBuffer to the any pointer V_t_Any_Header ?

Or do you mean I should initialize the destination pointer ?

Actually, the type of the destination pointer is an UDT. How can I initialize the pointer ?

Thanks for your help.

Best regards

Etienne

Hi,

In this thread our expert detail what to do and how:

ANY, POINTER in SCL

Anyways just to an example here BLKMOV copies data from a shared DB into a static area.

VAR_INPUT 
    DB_NUM : INT; // Source DB number 
    BYTEADDR : INT; // DB byte address of first byte to copy 
    COPY_LEN : INT; // Number of WORDS to be copied

...etc

//Initialize the ANY pointer
    pAny.S7Code:=16#10;  //specification of the syntax ID
    pAny.DataType:=16#4;  //code for the data type 2 FOR byte
    pAny.Length:=COPY_LEN;  //repeat factor
    pAny.DBNumber:=DB_NUM;  //number for data block
    pAny.MemoryArea:=16#84;
    pAny.ByteAddressMSB:=DWORD_TO_BYTE(SHR(IN:=(INT_TO_DWORD (BYTEADDR)),N:=13));//MSB
    pAny.ByteAddressLSB:=DWORD_TO_WORD(SHL(IN:=(INT_TO_DWORD (BYTEADDR)),N:=3));//LSB
    RetVal := BLKMOV(SRCBLK := pDB, DSTBLK := ACT_ALARM_W);//CALL BLKMOVE to save the alarms into the static area

...

I hope I could help.

Dear MicroMan,

thank you very much for your help.

I wonder if my message is clear enough. Sorry, I'm not fluent in English.

I would like to get the first 14 bytes of the data pointed by the any pointer used in the RECV argument of the AG_LRECV function.

VAR_INPUT 
    DB_NUM : INT; // Source DB number 
    BYTEADDR : INT; // DB byte address of first byte to copy 
    COPY_LEN : INT; // Number of WORDS to be copied

...etc

//Initialize the ANY pointer
    pDataRecv.Length:=14;//LSB

//Initialize the ANY pointer
    pAny.S7Code:=16#10;  //specification of the syntax ID
    pAny.DataType:=16#2;  //code for the data type 2 FOR byte
    pAny.DBNumber:=DB_NUM;  //number for data block
    pAny.MemoryArea:=16#84;
    pAny.ByteAddressMSB:=B#16#0;//MSB
    pAny.ByteAddressLSB:=W#16#0;//LSB

    pAny.Length:= 14;  //repeat factor

t_RetVal := BLKMOV(

SRCBLK:=pDataRecv,DSTBLK:=pAny);

Thanks,

Best regards,

Etienne Menot
 

Hi, 

It was an example to have a feel of it. I read back the original question.

• What do you exactly need? 
• Do you have a pointer set up to copy large amount of data into shared DB?
• Do you want the first 14byte to be copied into an other shared DB?

Note: You could reuse the already defined pointer, all you need is to change the length and define the destination in the same manner. We can draft up something for that but first answer the above questions as the ANY pointer is different for different data types/locations etc. I am happy to help you with that, but life is simpler...

The way I see your case after having a closer look. You do not even need indirect addressing. As your data is stored in a UDT within a shared DB, you can create a new block having a UDT input then just access it symbolically inside you block. See the solution in S7-SCL V5.3 for S7-300/400 manual chapter 7.4 User-Defined Data Types (UDT).

Keep it simple...

Just to be fair have a quick look at this example "FIFO" for buffering measured values about how to use UDT as block interface.

I hope I could help!

Hello MicroMan,

Actually, I'm developing a function block which sends and receives data between a S7 PLC and a computer via TCP Protocol.

All exchanged messages have the same structure. They are made up of a header and a byte array.

TYPE UDT_HEADER
STRUCT
    MSG_ID : INT := 0; // Message ID
    MSG_LEN : INT := 0; // Length of the message
    MSG_COUNTER : INT := 0;
    MSG_DT DATE_AND_TIME;
END_STRUCT;
END_TYPE

At input parameter of the FB, I defined the RECV_BUF parameter which is an any pointer. It allows to parameterize the data range in which data are saved.

In the FB, after receiving a message, I need to get the message ID and the message length containing in the header.

That's why I wonder how to extract the header of the received message.

Do you think I should use the BLKMOV SFC for doing it ?

Thanks,

Best regards,

Etienne

Hi, 

What about something like this?

create a STAT with the UDT "MOUVEMENT" call it like  LOCAL_MOU

create a TEMP ANY call it like  pDB, change the length as you need (byte number n+4  & n+5) and use it with BLKMOV. After that you should be able to access the data as local variable.

===============================================

RetVal := BLKMOV(SRCBLK := pDB, DSTBLK := LOCAL_MOU);

===============================================