Technical data

6.33 OB 254, OB 255: Transferring a Data Block to the DB RAM
Special function organization blocks OB 254 and OB 255 allow you
to transfer data blocks from the user memory to the DB RAM (data
block memory) of the CPU. The special functions OB 254 and 255 are
identical;
OB 254 is used for DX data blocks and OB 255 for DB data
blocks.
Application Shifting or duplicating a data block
Function
Shifting Shifting a data block from the user memory to the DB RAM
A data block is shifted from the user memory to the DB RAM and
retains its original block number. The new start address of the data
block is entered in the address list in DB 0.
Duplicating A data block in the user memory or in the DB RAM is duplicated in
the DB RAM and assigned a
new block number. The start address of
the new data block is entered in the address list in DB 0. The start
address of the old block is retained in DB 0, i.e. the original data
block remains valid.
The start address is only entered into DB 0 after the transfer is
completed and all identifiers are entered correctly in the block header.
The duplicated block is only accepted as valid or existing by the
system program after it has been completely transferred.
Note
Shifting DB0
into the DB-RAM is not possible since it already
exists in the DB-RAM. However, you can
duplicate DB 0.
6
OB 254, OB 255: Transferring a Data Block to the DB RAM
CPU 928B Programming Guide
C79000-B8576-C898-01
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