Siemens SIMATIC CPU 410 System Manual page 47

Note
Networking of PROFINET IO components
The PROFINET IO interfaces of our devices are set to "automatic setting" (autonegotiation)
by default. Verify that all devices connected to the PROFINET IO interface of the CPU are
also set to the "Autonegotiation" mode. This is the default setting of standard PROFINET
IO/Ethernet components.
If you connect a device to a PROFINET IO interface of the CPU that does not support the
"automatic setting" (Autonegotiation) operating mode or you choose a setting other than the
"automatic setting" (Autonegotiation) for this device, note the following:
• PROFINET IO requires 100 Mbps full-duplex operation, which means if the PROFINET
IO interface of the CPU is used simultaneously for PROFINET IO communication and
Ethernet communication, operation of the PROFINET IO interface is permissible only in
100 Mbps full-duplex mode.
• If an PROFINET IO interface of the CPU is used for Ethernet communication only, 100
Mbps full-duplex mode is possible.
Background: If a switch that is permanently set to "10 Mbps half-duplex" is connected to an
interface of the CPU, the "Autonegotiation" setting forces the CPU to adapt itself to the
settings of the partner device, which means the communication operates de facto at
"10 Mbps half-duplex". This is permitted for an Ethernet communication. But because
PROFINET IO demands operation at 100 Mbps full-duplex, this would not be a long-term
option to address IO devices.
Reference
● For details about PROFINET, refer to PROFINET System Description
(http://support.automation.siemens.com/WW/view/en/19292127)
● For detailed information about Ethernet networks, network configuration and network
components refer to SIMATIC NET Manual: Twisted-Pair and Fiber-Optic Networks
(http://support.automation.siemens.com/WW/view/en/8763736).
● For additional information about PROFINET IO, refer to: PROFINET
(http://www.profibus.com/)
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
Configuration of the CPU 410
3.5 PROFINET IO interfaces (X5, X8)
47