Service Life Of The Simatic Memory Card - Siemens S7-1500 Function Manual

SIMATIC memory card

4.4 Service life of the SIMATIC memory card

4.4 Service life of the SIMATIC memory card
Calculation of the theoretical service life of a SIMATIC memory card serves as a decision-
making aid for selecting which card you need for your automation task. The following
examples only return a guide value, however. A precise calculation of the service life is not
possible due to the fact that the description cannot cover all the theoretically possible
scenarios.
Influences on the service life
You can influence the service life of SIMATIC memory cards by the following factors:
● Size of card
● Number and type of write operations
The number of physical write operations to the memory blocks of the card results from the
following:
– Number of write operations from the application
– Type of write operations from the application
Structure of a SIMATIC memory card
The internal flash memory of the SIMATIC memory card is organized in memory blocks. A
memory block is a memory area of a fixed size. A write operation always addresses entire
memory blocks on the SIMATIC memory card. When a memory block has been written once
it must be deleted before it can be written again. The number of delete/write operations per
memory block is limited. The service life of the SIMATIC memory card is measured by the
maximum number of supported delete or write operations per memory block.
In contrast to delete or write operations, read operations have a negligible impact on the
service life. Therefore, the impact of the read operations on the service life is not included in
this calculation. A very high number of read operations can, however, influence the service
life to a small extent.
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Structure and Use of the CPU Memory
Function Manual, 10/2018, A5E03461664-AC