Indirect adressing S7

Hi folks,

I have a little question sure some of you will know this.

Example

Declaration
stats:
Adres1 "int"

Temp
Adres2 dword



Program

L 2
T adres1

L adres1
L 8
*I
T adres2

Opn DB200
L dbd[adres2]

So what i do is open DB200.DBD2

I use this alot but isn't there another way to make from the INT"adres1" a DWORD"adres2" except from multipling with 8


Ok

Probably alot of you would think why doesnt he program the following

L p#2.0
t adres2
opn db200
l dbd[adres2]

just because i want to explain it but then i would need to write a book why

Thanks in advantage

L adres1
SLD 3
T adres2

thx alot


SLD 3 means Shift left double 3 times i understand that

But yes there is allways a but
What is the relation between the Dword and the INT ?
or maybe it is a bad question how do you link the Dword to this one
0000_0000_0000_0010 in INT =2
SLD 3 gives i think this one
0000_0000_0000_0000_0000_0000_0001_0000 =2.0??
Or something else
I actually want to know how i can read the binary code and transformer in to a DWORD is there any rule to do this out of the head without using any program

Sorry for the stupid questions but i'm not a prof. programmer i learned this by myself and really want to understand this very good since i have noticed the power of indirect adressing.
And maybe i'm a guy how doesn't take an answer without explaination
What is a better solution of the both

The "multipling" or the "SLD3"

Are there any advantages or disadvantages ??

Thx alot allready

The shift takes less instructions and is quicker to execute than the multiply.

Sorry but I don't understand the other questions you are raising. Use a specific example to illustrate what you want to know. (and keep the font size down !)

Hello,
L 2#10 //load Binary code 10 to acc1
T ADD1
is equal
L 2
t ADD1

What is the format the PLC expects?

X.y

X = Byte offset
y = Bit offset

In binary that translates to:

0000_0000_0000_0000_0000_0000_0000_0000

The red is reserved for the bit offset. Bit offset can't be higher then 7, thus 3 bits reserved, hence the x8 or SLD 3. Rest is used for byte offset => your Int.

Why a Dword u ask? Well simple. If you should use Word for this your offset range would be limited to 8191.7 (full use of the 16 available bits)
Siemens uses Dword so u can use the full range of your DB's in indirect adressing.

Well thats what they made me believe...

Hope this helps

Oh ok i think i understand it

0000_0000_0000_0000_0000_0000_0000_1110= 1.6???
and
0000_0000_0000_0000_0000_0000_0001_0111=2.7??

Thx alot bot of you

yes,you are right.S7 have Signal word point and Double word point.The diffirent between these two point is ,
Signal poion is memery area numbering not include bit(0---65535) so it is only used for T C DB FC FB;
Double word point is include bit so it is can be used for bit addressing.if you want use double word point to area ex bit you must make sure the 0---2bit is zero.