Siemens S7-300 Configuration Manual page 41

3. Network the CP according to the instructions in STEP 7.
4. Check the module name and the addresses and change them if necessary. The
Address setting in the configuration and initial addressing
The address settings described here only reach the CP when the configuration data is
downloaded to it.
The following applies to the current Ethernet CPs:
To be able to reach the CP using these addresses even before the download, it is possible
to address the CP using the default MAC address and to supply it with further address
information.
The procedure for this initial address assignment is described in the section Assigning
addresses the first time (Page 76).
Configuring and commissioning S7 CPs for Industrial Ethernet
Configuration Manual, 09/2013, C79000-G8976-C182-13
addresses are entered automatically by identifying the next free address.
Note the following additional information:
– MAC address
The current Ethernet CPs are supplied with one or more default MAC addresses
depending on the number of interfaces (refer to the address printed on the module).
To ensure a unique address assignment, do not enter a MAC address in the
configuration (the option is disabled). This means that the module automatically uses
the address entered in the factory.
If you want to use the ISO services, we recommend that you use the MAC addresses
printed on the module for module configuration. This ensures that you assign a unique
MAC address in the subnet!
If you replace a module, the MAC address of the predecessor is adopted when you
load the configuration data. Configured ISO transport connections remain operable.
Note
If you change the CP modules regularly in your plant, when using ISO services you
can avoid double assignment of MAC addresses by, for example, by following the
steps outlined below:
1. Enter the first 3 manufacturer-specific bytes of the printed MAC address in the
configuration.
2. For the last 3 bytes, enter application-specific IDs for your CP (in the example "ik",
"nm", "yx" with a range of values in each case from 0 to 255 decimal).
Example: 00:0E:8C:ik:nm:xy
– IP address
With CPs with an additional gigabit interface, the IP address of the PROFINET
interface must not be in the same IP subnet as the IP address of the gigabit interface.
Note
The "IP address" and "Subnet mask" input boxes have no significance for ISO
transport (option "IP protocol is used").
Configuring the Ethernet CP with STEP 7
3.2 Configuring - follow the steps below
41