siemens adressing..

[basharath]

In simatic manager when we take MW1 then why we cant take MW2,rather it jumps to MW3 ??

 

[JesperMP]

Always address even bytes in Siemens S7.
MW0, MW2, MW4 ... etc.
DB1.DBW0, DB1.DBW2, DB1.DBW4 ... etc.

 

[hagos]

Siemens Addressing

In addition to what Jesper have said, there is an overlap between MW1 & MW2

MW1= MB1+MB2
MW2= MB2+MB3
If you could notice MB2 is the upper byte of MW1 , in the same time it is the lower byte of MW2.

To avoid this overlap there is an offset of two bytes when dealing with words, & an offset of four bytes when dealing with double words

MW0,MW2,MW4, etc....
MD0,MD4,MD8,etc...


Hagos

 

[Manglemender]

Edited.

Duplicated advice,

Nick

 

[boneless]

Time to go back to basics
Siemens always uses even numbers as mentioned. You can use uneven, but is not advised unless you know what you are doing.

1 byte = 8 bits
1 word (word-int-bcd) = 2 bytes
1 dword (dint-real) = 4 bytes

Just fool around with it in a DB. You will see how things divide out.