Siemens CPU 31 Series Technical Data Manual page 83

CPU 31xC and CPU 31x, Technical Data
Manual, 01/2006 Edition, A5E00105475-06
Note
As a precaution against loss of data, always make sure that you do not exceed the
maximum number of delete/write operations. Also refer to the SIMATIC Micro Memory
Card (MMC) section in the "Structure and Communication Connections of a CPU"
chapter.
Caution
Data on a SIMATIC Micro Memory Card can be corrupted if you remove the card while it
is being accessed by a write operation. In this case, you may have to delete the SIMATIC
Micro Memory Card on your PG, or format the card in the CPU. Never remove a
SIMATIC Micro Memory Card in RUN mode. Always remove it when power is off, or
when the CPU is in STOP state, and when the PG is not writing to the card. When the
CPU is in STOP mode and you cannot not determine whether or not a PG is writing to
the card (e.g. load/delete block), disconnect the communication lines.
Memory concept
4.2 Memory functions
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