Memory concept
6.2 Memory functions
6.2.3 CPU memory reset and restart
CPU memory reset
After the insertion/removal of a Micro Memory Card, a CPU memory reset restores defined
conditions for CPU restart (warm start).
Technology CPU:
• The CPU's memory management is rebuilt.
• Blocks in load memory are retained.
• All runtime-related blocks are transferred from the load memory to the working memory
again.
• The data blocks in the working memory are initialized (are thus reset to their initial
values).
Integrated technology of Technology CPU:
The CPU waits until the integrated technology has reached the STOP state.
• The integrated technology is parameterized again.
• The retentive memory of the integrated technology is rebuilt.
• Any distributed I/Os connected to DP(DRIVE) are parameterized again.
• The integrated technology is initialized again.
A description of the CPU memory reset procedure and its special features can be found in
chapter
CPU Memory Reset
of the S7-300 installation manual.
Warm Restart
What happens during a warm restart:
• All retentive DBs retain their current values.
• Non-retentive DBs are reset to their initial values.
• The values of all retentive M, C, T are retained.
• All non-retentive user data are initialized:
– M, C, T, I, O with "0"
• All run levels are initialized.
• The process images are deleted.
S7-300 CPU Data: CPU 315T-2 DP
Manual, 12/2005, A5E00427933-02
6-13
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