Variable size Array

Hello,

I wrote the following code for reading an element in array (whose size is 15) specifing position of the element in array:

FUNCTION Array_Read_Val_By_Index : VOID

TITLE = 'Read in array a value specified by index'

VAR_INPUT

    Array_In : ARRAY[1..15] OF INT; //Input Array

    Index : INT; //Index of the element that is to be readed

END_VAR

VAR_OUTPUT

    V_Out : INT; //Value of readed element

    Error : BOOL; //Error if index exceedes the lenght of array

END_VAR

    //Begin

    V_Out := 0;

    Error := False;

    IF (Index > 0 ) AND (Index <= 15) THEN

        V_Out := Array_In[Index];

    ELSE

        Error := True;

    END_IF;

END_FUNCTION

Hello,

If you use a S7-1200 or S7-1500, the function ReadFromArrayDB exists as such in the TIA catalog.
No need to rewrite something doing the same.

See picture in annex.

If you press F1 when the block is selected, you will have all details about that function.

Hello,

I'm working with a S7-300 CPU. However, the code posted is only for having a real example for my question. It's not important "how to read a value in array" but it's important to know how to pass a variable size array to a function and use it inside the function.

Thanks for your reply.

Best regards.

AlfredoSA

...

 Input array can also be stored in a temp variable, not only in DB, so I think I can't use ANY data type because it needs DB number in STRUCT.

...

 Hi!

ANY can be used to access other memory areas, not only DB memory. You just have to use a different area type code.

Thank you for your fast reply.

Can you post an example code, please, if you can?

Best regards.

Hi!

Search for smiffy's posts about the ANY pointer. You'll find there plenty of examples.

e.g.

https://support.industry.siemens.com/tf/us/en/posts/how-to-copy-data-block-in-scl/94234/?page=0&pageSize=10

Thanks for your reply. Trying to implement smiffy's examples, I did:

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;

END_VAR

VAR_OUTPUT

    oS7Code:BYTE;

    oDataType:BYTE;

    oLength:INT;

    oDBNumber:INT; 

END_VAR

BEGIN

pAny:= pArrayName;

oS7Code := MyAny.S7Code;

oDataType := MyAny.DataType;

oLength := MyAny.Length;

oDBNumber := MyAny.DBNumber;

END_FUNCTION

Hi!

I do not have v5.5 scl so cannot test your code, but it looks OK.

How do you pass the array to your function? Do you use a symbolic name or absolute address?

When a symbol name is used, the generated ANY pointer is converted to a Byte data type ANY. See page 6 of attached document.

Hi Kahl,

thanks for your reply. I wrote my function that accepts an ANY input, like in the Smiffy's examples and I used AT function for decompress ANY pointer. I passed the array in symbolic way. I tested 2 cases:

1. In the first case I created DB1 in which I created a variable MyArray whose type is ARRAY[1..100] of INT; I passed the array to the input as DB1.MyArray

2. In the second case I created in OB1 Interface a temp variable #MyArray whose type is ARRAY[1..100] of INT; I passed the array to the input as #MyArray

Is it wrong?

Thanks.

P.S.

Look at the image attached, that is referred to case 1. If I pass  DB1.MyArray to my function, I should have "Code for data type=5" and "Repetition factor=100", but test give me "Code for data type=2" and "Repetition factor=200". My output is ok.

Instead, if I pass temp variable #MyArray to my function, BLKMOV doesn't work and it gives me Ret Val=B#16#8122 (Dimension error during the reading of a parameter). 

How can I make my function able to work with my temp variable #MyArray?

Thanks.

Hi!

As a test, for the first case try to pass the array as P#DB1.DBX0.0 INT 1000 instead of DB1.MyArray and check the Data Type code.

(DBX0.0 or wherever your array starts)