Information for the Changeover to the Technology CPU
9.8 Using consistent data areas in the process image for DP slaves
9.8 9.8 Using consistent data areas in the process image for DP slaves
Using consistent data areas in the process image for DP slaves
A data area is consistent if it can be read or written to from the operating system as a
consistent block. Data exchanged collectively between the stations should belong together
and originate from a single processing cycle, that is, be consistent.
If the user program contains a programmed communication function, for example, access to
shared data with XSEND/ XRCV, access to that data area can be coordinated by means of
the "BUSY" parameter itself.
9.9 9.9 Load memory design for the Technology CPU
Load memory design for the Technology CPU
On CPUs 312 IFM to 318-2 DP, the load memory is integrated into the CPU and may be
extended with a memory card,
The load memory of the
Technology CPU is located on the Micro Memory Card (MMC). and
is retentive. When blocks are downloaded to the CPU, they are stored on the MMC and
cannot be lost even in the event of a power failure or memory reset.
Note
User programs can only be downloaded and thus the CPU can only be used if the MMC is
inserted.
9.10 9.10 Altered retentive response with a Technology CPU
Altered retentive response with a Technology CPU
With data blocks for the Technology CPU
• you can set the retentive response in the block properties of the DB.
• Using SFC 82 "CREA_DBL" -> Parameter ATTRIB, NON_RETAIN bit, you can specify if
the actual values of a DB should be maintained at POWER OFF/ON or STOP-RUN
(retentive DB) or if the start values should be read from the load memory (non-retentive
DB).
S7-300 CPU Data: CPU 315T-2 DP
9-6 Manual, 12/2005, A5E00427933-02
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