DB1.DBD4 extends through to DBB7, so DBB6 and DBB7 are part of var2.  var3 is strictly the low order 2 bytes of var2.

Is this what you intend?

Nicolayy

Hello.

I want to know why there is an automatic converting of data type given at transfer through direct addressing? And how to make so that it didn't occur?

S7-1200. TIA Portal V13 SP1 is used.

Example.

I create data block DB1 with name of "HMI_DB". There are 4 variables in the block:

var1  Real  DB1.DBD0 

var2  Real  DB1.DBD4

var3  Word  DB1.DBW6

var4  Word  DB1.DBW8

I want to use var3 and var4 as buffer for my "move" operations.

I want to move two words of var1 to (var3 and var4), then I want move result to var2:

%DB1.DBD0 := 24.7; // (for example), it is 16#41C5_999A

-------------

%DB1.DBW6 := %DB1.DBW0; // 16#41C5

%DB1.DBW8 := %DB1.DBW2; // 16#999A

%DB1.DBD4 := %DB1.DBD6; // (oops!) 16#4E83_8B33

Program automaticly convert /DINT_TO_REAL/ 16#41C5_999A (it is 1,103,468,954 in DEC format) to 16#4E83_8B33 (it is 1.103469e+009 in Real format). Why? I don't want this. I want to just move the words from one place to other place.

I understand, If I have written, that converting would have to happen:

"HMI_DB".var2 := %DB1.DBD6;

Because "HMI_DB".var2 is real variable. But %DB1.DBD4 is not real, it is just 4 bytes (like S7-200 addressing).

If I write so, it works correctly:

%DB1.DBW4 := %DB1.DBW6;

%DB1.DBW6 := %DB1.DBW8;

But I want to move double words, because it is convenient for my algorithms.

Create an FB that accepts 1 DWord and returns 1 DWord.

// IN1 : Dword; OUT1 : Dword

MOVE IN1 -> OUT1

Call the FB with IN1 := DB1.DBD8, OUT1 := DB1.DBD4

I also believe the plc should have issued you a warning during that implicit data conversion.  If it did, then you knew something odd might happen because you are not adding your own conversions.

Also, you can push a DINT into a DWORD, and a DWORD converts to a REAL just fine.

See attached image where I did that FB and used the convert instruction.

Both output reals started at 0.0.

Nicolayy

Hello.

I want to know why there is an automatic converting of data type given at transfer through direct addressing? And how to make so that it didn't occur?

S7-1200. TIA Portal V13 SP1 is used.

Example.

I create data block DB1 with name of "HMI_DB". There are 4 variables in the block:

var1  Real  DB1.DBD0 

var2  Real  DB1.DBD4

var3  Word  DB1.DBW6

var4  Word  DB1.DBW8

I want to use var3 and var4 as buffer for my "move" operations.

I want to move two words of var1 to (var3 and var4), then I want move result to var2:

%DB1.DBD0 := 24.7; // (for example), it is 16#41C5_999A

-------------

%DB1.DBW6 := %DB1.DBW0; // 16#41C5

%DB1.DBW8 := %DB1.DBW2; // 16#999A

%DB1.DBD4 := %DB1.DBD6; // (oops!) 16#4E83_8B33

Program automaticly convert /DINT_TO_REAL/ 16#41C5_999A (it is 1,103,468,954 in DEC format) to 16#4E83_8B33 (it is 1.103469e+009 in Real format). Why? I don't want this. I want to just move the words from one place to other place.

I understand, If I have written, that converting would have to happen:

"HMI_DB".var2 := %DB1.DBD6;

Because "HMI_DB".var2 is real variable. But %DB1.DBD4 is not real, it is just 4 bytes (like S7-200 addressing).

If I write so, it works correctly:

%DB1.DBW4 := %DB1.DBW6;

%DB1.DBW6 := %DB1.DBW8;

But I want to move double words, because it is convenient for my algorithms.

DB1.DBD0 is DWORD if I recall correctly because you are using an absolute address.

You can use the CONV block to convert from LREAL to DWORD and perform the MOVE from the CONV block output to a MOVE block.

Only tags it seems can be other than bit/byte/word/dword.  Tags can also be used with an absolute address

https://support.industry.siemens.com/cs/ww/de/view/57374718

Nicolayy

Program convert real to int, because compiler find symbol, you write. I understand it, okay:

%DB1.DBD4 := %DB1.DBD8; // 16#41C5_999A -> 16#4E83_8B33

 But! When I write assignment of number with a floating point, why does compiler not find symbol?

%DB1.DBD0 := 24.7

Datatype "LReal" cannot be converted implicitly to datatype "DWord".

Thus compiler doesn't know that DB1.DBD0 is a real type. It is strange