Siemens CP 342–5 Manual page 20

Note on 8. : Consistency in data transfer between CP and user program
Depending on the response in the user program, you can assume different areas
as consistent data areas on the transfer interface between the CP and user
program.
Note
Please note the information on programming FCs in the online help on the FCs
and in the manual /2/.
S Variant 1: NDR bit is evaluated on the FC interface
You can assume a consistency over the entire DP data area used.
S Variant 2: NDR bit is not evaluated on the FC interface
You can assume a data consistency in a contiguous, non overlapping 32-byte
area.
("Non overlapping" means that 32-byte areas are counted starting from base
address "0" of the relevant DP data area.)
Table 1-13 Consistency in the DP Master Mode
Data Access in User Program
Table 1-14 Consistency in the DP Slave Mode
Data Access in User Program
Note on 9. :FCs for the DP mode
New FCs are supplied with STEP 7 V5.1 for the CP 342-5 described here. The
following table shows how to use these new FC versions and the older FC versions
for the available modules:
20
Variant 1
Variant 2
Variant 1
Variant 2
Maximum Area with Data Consistency
2160 bytes
32 bytes
Maximum Area with Data Consistency
240 bytes
32 bytes
Manual CP 342–5 / CP 342–5 FO
C79000–G8976–C146/01