Communication via Function Blocks
6.7 Parameter assignment of the Function Blocks
CP 341 Point-to-Point Communication, Installation and Parameter Assignment
170
Manual, 09/2008, A5E02191071-01
6.7
Parameter assignment of the Function Blocks
6.7.1
General Information on Data Block Assignment
Introduction
This section is intended for users upgrading from SIMATIC S5 to SIMATIC S7. The following
sections contain important information on what you need to take into account when
programming function blocks in STEP 7.
Addressing
The data operands in data blocks are addressed bytewise in STEP 7 (in contrast to STEP 5,
where addressing is word-based). You therefore have to convert the addresses of the data
operands.
67(3
67(3
':>Q@
'5>Q@
'%:>Q@
'%%>Q@
'/>Q@
'%%>Q@
Figure 6-9
Comparison of data addressing in STEP 5 and STEP 7
The address of a data word is doubled in STEP 7 compared to STEP 5. It is no longer
divided into a low and a high data byte. The bits are always numbered from 0 through 7.
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