Shift DB X Bytes Siemens S7300

[Rusty_K]

Hello,

I'm looking for a way to shift the values of an entire DB up or down by X bytes (In my particular case it's 18 Bytes shifted up) Unfortuately the "Block Move" and "Fill" SFCs dont allow overlapping source and destination targets. The freed space ( Bottom 18 bytes after shift) should have "zero" values. Seems to me like this is a pretty basic question..sorry I'm still fairly new to this. Any help would be greatly appreciated.

Thank you kindly for your time

Cheers,

R.K.

 

[Rusty_K]

An Idea....

A quick look through the SFC blocks gave me an idea. :

- use SFC 22 to creat a DB
- use BlkMov to transfer the the part of my original DB I wish to shift, to the newly created DB
- use BlkMove again to transfer data values in my newly created DB to my original DB, shifted up 18 bytes
- Finally use SFC 23 to delete the newly created DB

Is this at all a good idea? Is there a more efficent way of shifting the 18 bytes?
Cheers,

R.K.

 

[Rusty_K]

Right on...so this worked fairly well...and on my first try!

Still, any feedback from you pros out there will be greatly appreciated!

Cheers,

R.K.

 

[SimonGoldsworthy]

If the number of bytes to shift and the direction varies then what you have done is spot on.