Siemens S7-1500 Function Manual page 70

Maximum number of write/delete operations
The internal controller of the memory card ensures that the available memory blocks are
evenly used. In this way, a maximum number of write operations is possible on the SIMATIC
memory card. Internal algorithms distribute the write accesses to the same logical memory
area over changing physical memory areas in order to use the memory blocks evenly.
The following table shows the maximum possible number of write/delete operations as a
function of the SIMATIC memory card used. The number of maximum write/delete
operations of the respective SIMATIC memory card is also available online in the technical
specifications of the respective SIMATIC memory card.
Memory size of the SIMATIC memory
card *
4 MB
12 MB
24 MB
256 MB
2 GB
2 GB
32 GB
* The memory size figures named in the table are theoretical values. The actual existing memory size in practice is below
the theoretical value. The reason for this is that the internal controller of the card and the file system reserve part of the
existing memory for internal memory management.
Note
Write or delete operations
Write or delete operations, particularly repeated (cyclic) write/delete operations by the user
program on the SIMATIC memory card reduces its service life.
Cyclic execution of the following instructions reduces the service life of the memory card
depending on the number of write operations and data:
• "CREATE_DB" (with ATTRIB "Create DB in load memory")
• "DataLogWrite"
• "RecipeExport"
• "RecipeImport" (if target DB in load memory)
• "WRIT_DBL"
• "SET_TIMEZONE"
Note also that, in addition to the cyclic write/delete operations, the writing or deleting of very
large amounts of data also adversely affects the service life of the SIMATIC memory card.
Note
Redundant system S7-1500R/H
The CPUs of the redundant system S7-1500R/H do not support the instructions specified in
this "Write or delete operations" notice, except for "SET_TIMEZONE".
Structure and Use of the CPU Memory
Function Manual, 10/2018, A5E03461664-AC
4.4 Service life of the SIMATIC memory card
Article number
6ES7954-8LCxx-0AA0
6ES7954-8LExx-0AA0
6ES7954-8LFxx-0AA0
6ES7954-8LL02-0AA0
6ES7954-8LP01-0AA0
6ES7954-8LP02-0AA0
6ES7954-8LT02-0AA0
SIMATIC memory card
Max. number of write/delete operations per
memory block
500 000
500 000
500 000
200 000
100 000
60 000
50 000
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