Siemens SIMATIC ET 200AL, System Manual

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Parameter assignment/addressing
3.2 Device name and IP address
PROFINET with STEP 7
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Function Manual, 05/2021, A5E03444486-AL
Generating IP addresses
You assign the IP addresses of the IO devices in STEP 7. The IO devices receive their
IP addresses during parameter assignment by the IO controller.
In addition, for some IO devices (e.g., SCALANCE X, S7-300 CPs), it is possible not to obtain
the IP address during startup of the IO controller, but rather to set it beforehand on the
device (see Permitting changes to the device name and IP address directly on the device
(Page 1)).
The IP addresses of the IO devices always have the same subnet mask as the IO controller and
are assigned from the IP address of the IO controller in ascending order. The IP address can be
changed manually, if necessary.
For devices with several PROFINET interfaces (e.g., CPU 1516-3 PN/DP), the IP addresses must
be located in different subnets.
Note
Assignment of the IP address by a DHCP server
As of STEP 7 V17, you can select the option "IP address from DHCP server" for the PROFINET
interface. With this option, the PROFINET interface is assigned an IP address by an DHCP
server.
When you configure the option "IP address from DHCP server" for a PROFINET interface, this
interface does no longer support the PROFINET IO functionality.
For more information on addressing by a DHCP server, please refer to the Communication
( http://support.automation.siemens.com/WW/view/en/59192925 ) function manual.
Default router
The default router is used when data has to be forwarded via TCP/IP or UDP to a partner
located outside the local network.
In STEP 7, the default router is named Router. You can activate the use of a router in the
Inspector window of a CPU with the "Use router" check box in the "IP protocol" section. STEP 7
assigns the local IP address to the default router by default.
The router address that is set on the PROFINET interface of the IO controller is automatically
transferred for the configured IO devices.
Subnet mask
The bits set in the subnet mask decide the part of the IP address that contains the address of
the network.
In general, the following applies:
•
The network address is obtained from the AND operation of the IP address and subnet
mask.
• The device address is obtained from the AND NOT operation of the IP address and subnet
mask.