Variable size Array

Hi Kahl,

ok, in the first case  now it works: if I pass DB1.DB0.0 INT 1000, I have "Code for data type=5" and "Repetition factor=100" .

Now, can you help me with the last question, please? Why if I pass temp variable #MyArray, BLKMOV gives me Ret_Val=B#16#8122? Temp variable #MyArray starts at the address 532.0 in OB1 Interface and I pass it at my function as P#L532.0 INT 100.

Hi!

   Regarding the example with  DB1.DB0.0 INT 100, I just wanted to show you what the attached document states on  page 6:

"The user may enter an “absolute” form of the ANY pointer, or the user may apply a symbolic variable to the parameter. When a symbol name is applied to the ANY pointer input of a function or function block, it is converted to an “absolute” ANY pointer whose starting address is the address of the symbol, whose data type is BYTE, and whose length if the byte length of  the defined symbol (for instance, a REAL element would have a byte length of 4)."

   Regarding the second part with #MyArray, I do not see any BLKMOV in your example code. Anyway, looks like something is wrong with the source and destination memory areas (see last point of link). Maybe the local stack of OB1 is too small for your array - I don't know.

LINK

You could try to construct an ANY pointer which points to #MyArray as in smiffy's example, and use that with BLKMOV:

pAnySRC.S7Code := 16#10;
pAnySRC.DataType := 16#05;   //Int
pAnySRC.Length := 100;
pAnySRC.DBNumber := 0;
pAnySRC.MemoryArea := 16#87;  // temp local of the calling block
pAnySRC.ByteAddressMSB := 0;
pAnySRC.ByteAddressLSB := INT_TO_WORD( 532*8);  // bitwise addressing

PS another good example from smiffy:

https://support.industry.siemens.com/tf/ww/en/posts/any-pointer-in-scl/50677/?page=0&pageSize=10

Hi Kahl,

thanks so much for your explanations. The function I'm testing is the following:

FUNCTION FC100 : VOID

VAR_INPUT

    pArrayName:ANY;

END_VAR

VAR_TEMP

    pAny:ANY;

    MyAny AT pAny:STRUCT

    S7Code : BYTE; // Code for S7 = 0x10

    DataType : BYTE; // Code for data type = 0x02 = byte

    Length : INT; // Repetition factor = Send/receive length

    DBNumber : INT; // Data block Number

    MemoryArea : BYTE; // Specified memory area = 0x84 = data block

    ByteAddressMSB : BYTE; // Byte address most significant bits

    ByteAddressLSB : WORD; // Byte address least significant bits

    END_STRUCT;

    RetVal : INT;

    myWord : INT;

    iType:INT;

    Index:INT;

END_VAR

VAR_OUTPUT

    oS7Code:BYTE;

    oDataType:BYTE;

    oLength:INT;

    oDBNumber:INT;

    oRetVal : INT;

    oWord : INT; 

    oMemArea: BYTE;

END_VAR

BEGIN

pAny:= pArrayName;

Index:=4; // Read the fifth element of array

MyAny.ByteAddressLSB := INT_TO_WORD(WORD_TO_INT(MyAny.ByteAddressLSB) + (16*Index));

RetVal := BLKMOV(SRCBLK := pAny, DSTBLK := myWord);

oRetVal := RetVal;

oWord := myWord;

oS7Code := MyAny.S7Code;

oDataType := MyAny.DataType;

oLength := MyAny.Length;

oDBNumber := MyAny.DBNumber;

oMemArea := MyAny.MemoryArea;

END_FUNCTION

AlfredoSA

....  but it doesn't work if I pass temp #TestArray.

 Hi!

What does not work? What happens?

Hi.

I'm moving 123 in #TestArray[5] but output oWord is 64. If I try to move another number in #TestArray[5], oWord is always 64...

If it can be useful, I noticed that MemoryArea of ANY pointer (byte 6) in my test is "16#87=Previous Local Data (V) and not "16#86=Local Data (L stack)". Is it correct?

Hi!

MyAny.ByteAddressLSB := INT_TO_WORD(WORD_TO_INT(MyAny.ByteAddressLSB) + (16*Index));

Move the declaration of Index from VAR_TEMP to VAR_INPUT and tell your function which element of the array do you need.

PS Sorry! I've just seen that you initialized Index inside the function. But, you can still make Index an input variable.

You should look inside MyAny.ByteAddressLSB to see what address is inside it, when Index=4.

Hi, Kahl and sorry for my perservering.

I've modified FC100 so that now Index is an input (MW800) and also

MyAny.ByteAddressLSB := INT_TO_WORD(WORD_TO_INT(MyAny.ByteAddressLSB) + (16*(Index-1)));

But the problem still persist. LSB behaviour is correct, but Output has strange values:

Index   |   LSB     |   Output   |   RetVal

1           |   0          |   16          |   W#16#00

2           |   16        |   0            |   W#16#00

3           |   32        |   0            |   W#16#00

4           |   48        |   -121      |   W#16#00

5           |   64        |   64          |   W#16#00

..............

20         |   304     |   0            |   W#16#8122

Furthermore, when index is 20 and more, RetVal for BLKMOV give me error W#16#8122, although #TestArray is an array of 100 INT.

Any ideas?

Thanks.

P.S. The problem is only with Local Variable #TestArray: if input is an array from DB, function works. 

Hi!

When index is 20 or higher, you probably reach the limit of the local data stack. The size of this memory is CPU dependent, e.g. for 315-2DP I think it is 1024 bytes.

From this point on I can only guess regrading the strange values you get.

The local data of an FC is available for another block called inside the FC, but maybe it is lost if you pass only a pointer to the called block. We're missing something here. Maybe an expert could help us with this.

I would definitely do a test with an only-10-element array, and would use an FB instead of an FC. There you can use the static part of the instance DB to store your array.

Hi Kahl,

thanks so much for your support. Now many things are more clear. However, I can't believe the problem is the limited quantity of memory for local variables, but there is something wrong or some information I don't know. 

However, if you can pass this issue to a more expert techincian, I will be very greatful with you.

Thanks again for your help.

Best regards.