Siemens SIMATIC NET S7-300 Manual page 89

Relocating the CP in the Hardware Configuration
If you are using communication services with configured connections, the
connection IDs also identify the slot of the CP. If you "drag" a CP you have already
configured to a different slot, note the following:
Notice
If you drag the CP to a different slot, the data of the connection configuration are
automatically updated. The data of the connection configuration must, however, be
downloaded again!
S7-CPs for Industrial Ethernet Configuring and Commissioning
Release 01/2007
C79000-G8976-C182-07
3 Operating the Ethernet CP with
A -89