Siemens Simatic S7-300 Technical Data Manual page 72

Memory concept
4.1 Memory areas and retentivity
MMC copy protection
Your MMC has an internal serial number that provides copy protection at user level. You can
read this serial number from the SSL partial list 011C
You can then program a STOP command, for example, in a copy-protected block if the
expected and actual serial numbers of your MCC do not tally.
Reference
•
• in the manual
Useful life of an MMC
The useful life of an MMC depends mainly on following criteria:
1. The number of delete or programming operations,
2. External influences such as ambient temperature.
At ambient temperatures up to 60 °C, a maximum of 100,000 delete/write operations can be
performed on an MMC.
Caution
To prevent loss of data, always make sure that you do not exceed the maximum number of
delete/write operations.
See also
Operating and display elements: CPU 31xC (Page 2-1)
Operating and display elements: CPU 312, 314, 315-2 DP: (Page 2-5)
Operating and display elements: CPU 317-2 DP (Page 2-7)
Operating and display elements: CPU 31x-2 PN/DP (Page 2-9)
4-10
SSL partial list in the instruction list,
System and Standard Functions.
Operating instructions CPU 31xC and CPU31x, Commissioning, Commissioning
Modules, CPU Memory Reset by means of Mode Selector Switch
index 8 using SFC 51 "RDSYSST."
H
or
Information on CPU memory reset:
CPU 31xC and CPU 31x, Technical data
Manual, Edition 08/2004, A5E00105475-05