A PROFINET network running in IRT mode requires industrial Ethernet switches that are specifically IRT-certified and implement precise time-based scheduling (typically prioritised cut-through forwarding).
True
IRT-aware switches are industrial Ethernet switches that combine precise clock synchronisation (usually PTP IEEE 1588), time-slot based scheduling, support for the MRP (Media Redundancy Protocol) on ring topologies, and very low deterministic latency. Typical examples are the Siemens SCALANCE X family, Hirschmann RSP/MICE and Phoenix Contact FL SWITCH 2000/3000. Standard IT switches (TP-Link, Netgear and the like) cannot support IRT because their forwarding plane is neither time-aware nor synchronised.
If you cannot find the words "IRT" or "PROFINET CC-C" on the switch datasheet, assume it is not suitable for IRT, regardless of how good its general specs look.
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