Structure of a CPU 41x
2.7 Structure and Functions of the Memory Cards
S7-400 Automation System, CPU Specifications
2-18 Manual, 10/2006, 6ES7498-8AA04-8BA0
Serial Number
As from Version 5 the memory cards have a serial number. This serial number is listed in
INDEX 8 of the SZL Parts List W#16#xy1C. The parts list can be read out using the SFC 51
"RDSYSST".
You can determine the following when you read the serial number into your user program:
The user program can only be started when a specific memory card is inserted in the CPU.
This protects against unauthorized copying of the user program, similar to a dongle.
See also
Overview of the memory concept of S7-400 CPUs (Page 8-1)
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