Troubleshoot with byte even in a DB

fredlnord

Hello,

I have a probleme with a DB in portal v11 SP2. When i create a db with 1 byte and 1 word the first byte have the address 0.0, but the word have the adresse 2.0 . I don't understand. On the over hand when i create one byte at the address 0.0 and the second at the address 1.0, the word take the address 2.0 ???
We have one additional byte when we start with an even address.

Who have an explication .

Thanks

best regard.

Thanks for your answer huggy, but for me when you use in a db a byte and after a word, you access to your byte at dbx.dbb0 and to your word dbx.dbw1.I don't understand whyI do lost memory. I could do that in step 7. WhyI can't do it in portal ?

fredlnord

Thanks for your answer huggy, but for me when you use in a db a byte and after a word, you access to your byte at dbx.dbb0 and to your word dbx.dbw1.I don't understand whyI do lost memory. I could do that in step 7. WhyI can't do it in portal ?

fritz

Hello fredlnord

not too sure if it helps, but I can tell you that the "classic" Step 7 (e.g. V5.x) behaves in the same fashion as the TIA PortalStep 7.
Any 16 bit or longer dataype (e.g.WORD, INT, REAL etc.) will be allocated an even startaddress in the DB.

You can avoid your"gap" by either restructering your DB or - if you use a 1200 - by setting the DB properties to "optimized block access" when creating the DB. This new "feature" is something that only S7-1200'soffer, but you will in that case be forced to work purely symbolically and loose the ability to directly access the adresses in the DB.

I hope this helps