Siemens S7-1500 Function Manual page 72

Automation system

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Calculation of the theoretical service life of a SIMATIC memory card

We will use the following example as a basis for calculation:

The user is using a new 256 MB memory card. In accordance with the table, this memory

card type supports 200000 write operations. After parameter changes, the user would like to

write 200 data blocks of 5 Kbytes each to the SIMATIC memory card at a frequency of

50 times per day with the "RecipeExport" instruction.

Step 1: Calculating the write operations

First use the following formula to calculate the service life of the SIMATIC memory card:

We first use the sizes from the example in the formula "Write operations" as a basis for

calculating the service life:

● Size of the memory card: 256 MB = 268435456 bytes

● Maximum number of write operations: 200000

● Number of written bytes: 1024000 bytes (200 x 5 KB)

If we use the sizes from the example in the formula, we obtain the following result:

Step 2: Calculating the service life

Use the following formula to calculate the service life in years:

Note

Net-gross factor

Internal data (metadata) are also written to the SIMATIC memory card with each write

operation. Due to this additional data, include the net-gross factor 10 when calculating the

service life.

If we use the sizes from the example in the formula, we obtain the following result:

Structure and Use of the CPU Memory

Function Manual, 10/2018, A5E03461664-AC

SIMATIC memory card

4.4 Service life of the SIMATIC memory card

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Et 200pro Et 200sp