PROFINET® is a deterministic industrial network protocol which supports many existing legacy field bus systems such as PROFIBUS®, DeviceNet, Interbus, Modbus®, AS-Interface and IEC 61158-2 networks. This legacy bus support reduces the need to obsolete existing equipment.

It supports full Ethernet compliant connectivity for component-based automation, and allows configuration with standard office tools like SNMP and browser-based monitoring for remote configuration and maintenance. Alternatively, one can continue to use tools similar to those for PROFIBUS systems

PROFINET systems can be one of three types that are differentiated mainly according to how they handle cycle time and jitter.  Cycle time is the time for a message to travel between devices and jitter is variability in network cycle time.

•  PROFINET V1 was the first version using conventional Ethernet, which offers no real-time features.  About half of industrial automation applications are non-real-time (NRT) and can accept cycle time greater than 100 milliseconds.
• PROFINET RT – Real Time (was V2) offers moderate real-time features using conventional Ethernet.  It is useful for approximately 30% of applications which are real-time needing cycle time between 1 and 100 milliseconds.
• PROFINET IRT – Isochronous Real Time (was V3) offers high real-time features for applications such as motion control, and usually requires a special ASIC.  The remaining 20% of industrial applications need isochronous real-time characteristics with very fast cycle time less than 1 millisecond and jitter less than 1 microsecond.  For these applications, PROFINET IRT offers special advantages, including:
  • A time slicing mechanism which makes highly efficient use of standard Ethernet telegrams
  • Support for up to 150 axes of motion, which is more than any other Ethernet solution
  • Ethernet switches built into at least one ASIC solution to daisy-chain PROFINET devices to reduce the network cost
  • Easier deployment of redundant networ

The PROFINET Trade Organization (PTO) continues to add new features such as advanced security, in new specifications such as PROFIsafe and PROFIdrive.