Which switch for PROFINET networks?
PROFINET switches are considered to be manageable industrial switches for which the manufacturer supplies a GSD file. With the GSD file, you can insert the switch into the HW configuration of the PLC and manage the switches via the PLC program. If you do not need to insert the switch into a PLC project, then choose industrial manageable switches that support LLDP and SNMP. With these two protocols, you can use diagnostic tools to generate the PROFINET network topology, see corrupted packets on individual switch ports, how long a port has been running, the data flow on individual ports, and many other useful information.
Managed switches handle packets much faster and better. They allow you to perform better diagnostics of the PROFINET network, find errors more easily and thus minimize unplanned downtime and costs in the event of a communication failure. We do not recommend using unmanageable switches in PROFINET networks.
The last argument for using PROFINET managed switches is the PROFINET protocol specification, which states that class B devices (B Class) should be installed in PROFINET networks, and in our case, these are managed Ethernet switches. Class B requires that the devices have internal diagnostics, can detect and identify connected PROFINET devices on their ports (this is how the network topology is created), and provide diagnostic and configuration information about themselves via SNMP. Neither of these requirements is met by the unmanageable switch. It is true that the PROFINET network will probably work on these unmanageable devices, but as soon as there are problems with the network or you want to set up more security, etc., these switches will have to be replaced by manageable ones. For these reasons, we do not recommend using unmanageable switches in PROFINET networks.
Beware of another common misconception, namely that the designation "industrial Ethernet switch" does not mean that the switch is a manageable switch.
For reliable operation of PROFINET networks, we recommend switches from SIEMENS of the SCALANCE X-200 series and higher.
