Profinet
Profinet is an industrial Ethernet standard maintained by PROFIBUS & PROFINET International and commonly used with Siemens automation. It carries real-time I/O between controllers and field devices on standard Ethernet hardware and is the successor to the serial Profibus fieldbus.
Profinet defines several traffic classes: non-real-time over TCP/IP for configuration, real-time (RT) for cyclic I/O, and isochronous real-time (IRT) for motion control with hardware-level timing. Device discovery and naming use the DCP protocol at Layer 2, which means Profinet devices are found and configured by anything in the same broadcast domain.
Legacy Profibus segments are often still in service alongside Profinet, bridged through gateways that are easy to overlook in an inventory.
Why it matters in cement, mining, and aggregates
Cement plants built on Siemens automation commonly run Profinet on the kiln and mill networks and Profibus on older sections. An assessment maps both, including the gateways, because a gateway reachable from the office network is a path to the fieldbus.