Operations In The Cpu During A Memory Reset - Siemens S7-300 Installation Manual

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Table 9-5

Operations in the CPU during a memory reset

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CPU activities 1.
2.
3.
4.
Memory contents The status of CPU memory space is "0". If a memory card
after reset has been inserted, the user program is transferred back to
the main memory.
What's left? Data in the diagnostics buffer.
You can read the diagnostic buffer with the PG (see 67(3  2QOLQH +HOS).
The MPI parameters (MPI address and highest MPI address, transmission rate,
configured MPI addresses of CPs/FMs in an S7-300).
The contents of the operating hours counter (not for CPU 312 IFM).
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MPI parameters hold a special position when memory is reset. The table below
describes MPI parameters remaining valid after memory reset.
With inserted memory card
With integrated FEPROM load memory
(CPU 312 IFM / 314 IFM (314-5AE0x)
9-16
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The CPU deletes the complete user program in main memory and RAM load
memory.
The CPU deletes the retentive data.
The CPU tests its own hardware.
If a memory card is inserted, the CPU copies its
sequence-relevant data to the main memory.
7LS If the CPU cannot copy the data on Memory Card
or MMC and requests memory reset:
•
Remove the memory card
•
Resetting CPU memory
•
Read the diagnostic buffer.
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The CPU copies
runtime relevant data
from EPROM memory
to main memory
The user program is
loaded back into the
RAM from the
integrated retentive
EPROM of the CPU.
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... located on the memory card or on the
integrated FEPROM of the CPU are valid. If
this location does not contain parameter
data (SDB), the previously set parameters
stay valid.
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