Siemens SIMATIC S7-300 Equipment Manual page 64

Diagnostics and maintenance
7.4 Replacing a module
Module replacement: Special feature of IP address assignment from a DHCP server
During configuration of the CP you can specify the IP configuration in the properties dialog;
one option is to obtain the IP address from a DHCP server.
Note
When replacing modules, please remember that the factoryset MAC address of the new
module is different from the previous module. When the factoryset MAC address of the new
module is sent to the DHCP server, this will return either a different or possibly no IP address.
Ideally, you should therefore configure IP as follows:
Always configure a client ID if you want to obtain the same IP address from the DHCP server
after replacing the module.
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Equipment Manual, 01/2023, C79000−G8976−C198−09
CP 343-1 Lean