Siemens SIMATIC S5 Manual page 298

FC162
Allocation of the Data Blocks
Introduction
In SIMATIC S7, the addresses of the data operands are always counted by
bytes. The address of an S5 data word (DW n) corresponds to the address
DBW (2*n) of the S7 data word.
The data block allocation has been retained as far as possible.
Sole deviation from S5:
In SIMATIC S7, indirect addressing can directly be done via the block parame-
ters. Consequently, the corresponding allocation in the work area of the DB-A
data block is no longer necessary.
7–20
IP244
C79000–B8576–C866–01