Introduction of topology detection
The PROFINET technology detection allows for configuring and monitoring the structure of the network with the PROFINET IO controller in addition to the PROFINET IO devices.
The so-called "Physical device" (PDEV) is the starting point for the configuration. PDEV is a model for the Ethernet interface and can be found in slot0 in the configuration with an "Ethernet interface" subslot and one subslot for each Ethernet port.
The Ethernet ports made visible in this way can be connected to the configuration tool. The result is an image of the desired Ethernet routing for the plant. This image is stored in the PROFINET IO controller.
In order to be able to determine the real plant topology, the PROFINET IO devices must support the so-called LLDP (Link Layer Discovery Protocol). The PROFINET IO devices exchange information with the neighboring PROFINET IO devices via LLDP. Each PROFINET IO device cyclically sends information about its own PROFINET device name and port number via LLDP. The neighboring device receives and stores this information. A PROFINET IO controller can then read the stored information from the PROFINET IO devices and so determine the real plant topology.
By comparing the configured topology with the real topology, you can detect any missing or incorrectly wired PROFINET IO devices and localize them in the plant.
Apart from cabling, you can still determine the transmission characteristics for the ports. For example, you can set an "Auto-negotiation" port to "100 Mbit full duplex". The settings will be monitored.
SNMP (Simple Network Management Protocol) as a protocol for network diagnostics extends the topology detection by standard diagnostics mechanisms from the IT area.
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