Siemens SIMATIC S7 System Manual page 128

98BDevice configuration
5.6 Configuring the CPU for communication
Note
All IP addresses are configured when you download the project. If the CPU does not have a
pre-configured IP address, you must associate the project with the MAC address of the
target device. If your CPU is connected to a router on a network, you must also enter the IP
address of the router.
The "Set IP address using a different method" radio button allows you to change the IP
address online or by using the "T_CONFIG (Page 421)" instruction after the program is
downloaded. This IP address assignment method is for the CPU only.
When changing the IP address of a CPU online or from the user program, it is possible to
create a condition in which the PROFINET network may stop.
If the IP address of a CPU is changed to an IP address outside the subnet, the PROFINET
network will lose communication, and all data exchange will stop. User equipment may be
configured to keep running under these conditions. Loss of PROFINET communication may
result in unexpected machine or process operations, causing death, severe personal injury,
or property damage if proper precautions are not taken.
If an IP address must be changed manually, ensure that the new IP address lies within the
subnet.
128
WARNING
IP addresses properties: In
the Properties window,
select the "Ethernet
addresses" configuration
entry. STEP 7 displays the
Ethernet address
configuration dialog, which
associates the software
project with the IP address
of the CPU that will receive
that project.
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05